Format credit card in edit text in android

2019-01-12 21:36发布

问题:

How to make EditText accept input in format:

4digit 4digit 4digit 4digit 

I tried Custom format edit text input android to accept credit card number, but unfortunately I was unable to delete the spaces. Whenever there is a space, I could not to delete it. Please help me in finding out the issue.

回答1:

After finding multiple answers that are 'OK'. I moved towards a better TextWatcher which is designed to work correctly and independently from the TextView.

TextWatcher class is as follows:

/**
 * Formats the watched EditText to a credit card number
 */
public static class FourDigitCardFormatWatcher implements TextWatcher {

    // Change this to what you want... ' ', '-' etc..
    private static final char space = ' ';

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
    }

    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
    }

    @Override
    public void afterTextChanged(Editable s) {
        // Remove spacing char
        if (s.length() > 0 && (s.length() % 5) == 0) {
            final char c = s.charAt(s.length() - 1);
            if (space == c) {
                s.delete(s.length() - 1, s.length());
            }
        }
        // Insert char where needed.
        if (s.length() > 0 && (s.length() % 5) == 0) {
            char c = s.charAt(s.length() - 1);
            // Only if its a digit where there should be a space we insert a space
            if (Character.isDigit(c) && TextUtils.split(s.toString(), String.valueOf(space)).length <= 3) {
                s.insert(s.length() - 1, String.valueOf(space));
            }
        }
    }
}

Then add it to your TextView as you would any other TextWatcher.

{
  //...
  mEditTextCreditCard.addTextChangedListener(new FourDigitCardFormatWatcher()); 
}

This will auto delete the space sensibly going back so the user can actually do less keystrokes when editing.

Caveat

If you are using inputType="numberDigit" this will disable the '-' and ' ' chars, so I recommend using, inputType="phone". This enables other chars, but just use a custom inputfilter and problem solved.



回答2:

Example on github.com

Late answer, but I guess it may helpful for somebody:

    cardNumberEditText.addTextChangedListener(new TextWatcher() {

        private static final int TOTAL_SYMBOLS = 19; // size of pattern 0000-0000-0000-0000
        private static final int TOTAL_DIGITS = 16; // max numbers of digits in pattern: 0000 x 4
        private static final int DIVIDER_MODULO = 5; // means divider position is every 5th symbol beginning with 1
        private static final int DIVIDER_POSITION = DIVIDER_MODULO - 1; // means divider position is every 4th symbol beginning with 0
        private static final char DIVIDER = '-';

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            // noop
        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
            // noop
        }

        @Override
        public void afterTextChanged(Editable s) {
            if (!isInputCorrect(s, TOTAL_SYMBOLS, DIVIDER_MODULO, DIVIDER)) {
                s.replace(0, s.length(), buildCorrectString(getDigitArray(s, TOTAL_DIGITS), DIVIDER_POSITION, DIVIDER));
            }
        }

        private boolean isInputCorrect(Editable s, int totalSymbols, int dividerModulo, char divider) {
            boolean isCorrect = s.length() <= totalSymbols; // check size of entered string
            for (int i = 0; i < s.length(); i++) { // check that every element is right
                if (i > 0 && (i + 1) % dividerModulo == 0) {
                    isCorrect &= divider == s.charAt(i);
                } else {
                    isCorrect &= Character.isDigit(s.charAt(i));
                }
            }
            return isCorrect;
        }

        private String buildCorrectString(char[] digits, int dividerPosition, char divider) {
            final StringBuilder formatted = new StringBuilder();

            for (int i = 0; i < digits.length; i++) {
                if (digits[i] != 0) {
                    formatted.append(digits[i]);
                    if ((i > 0) && (i < (digits.length - 1)) && (((i + 1) % dividerPosition) == 0)) {
                        formatted.append(divider);
                    }
                }
            }

            return formatted.toString();
        }

        private char[] getDigitArray(final Editable s, final int size) {
            char[] digits = new char[size];
            int index = 0;
            for (int i = 0; i < s.length() && index < size; i++) {
                char current = s.charAt(i);
                if (Character.isDigit(current)) {
                    digits[index] = current;
                    index++;
                }
            }
            return digits;
        }
    });

this works perfectly with start-string/end-string/mid-string editing, also paste works perfectly.



回答3:

I modified Chris Jenkins answer to make it more robust. With this, even if the user edits the middle of the text, the spacing characters are still inserted (and automatically removed on wrong places) correctly.

To make this work correctly, make sure the EditText attributes are set as follows (note the space on digits):

android:digits="01234 56789"
android:inputType="number"
android:maxLength="19"

Then here is the TextWatcher you need. The anonymous class can also be made static since this is independent of the EditText.

    yourTextView.addTextChangedListener(new TextWatcher() {
        private static final char space = ' ';

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {
        }

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {
        }

        @Override
        public void afterTextChanged(Editable s) {
            // Remove all spacing char
            int pos = 0;
            while (true) {
                if (pos >= s.length()) break;
                if (space == s.charAt(pos) && (((pos + 1) % 5) != 0 || pos + 1 == s.length())) {
                    s.delete(pos, pos + 1);
                } else {
                    pos++;
                }
            }

            // Insert char where needed.
            pos = 4;
            while (true) {
                if (pos >= s.length()) break;
                final char c = s.charAt(pos);
                // Only if its a digit where there should be a space we insert a space
                if ("0123456789".indexOf(c) >= 0) {
                    s.insert(pos, "" + space);
                }
                pos += 5;
            }
        }
    });


回答4:

Here is a cleaner solution using regular expressions. Although regular expressions can be inefficient, they would be sufficient in this case since it's processing a string of at most 19 characters, even if the processing occurs after each key press.

editTxtCardNumber.addTextChangedListener(new TextWatcher() {

    @Override
    public void onTextChanged(CharSequence s, int arg1, int arg2,
            int arg3) { }

    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) { }

    @Override
    public void afterTextChanged(Editable s) {
        String initial = s.toString();
        // remove all non-digits characters
        String processed = initial.replaceAll("\\D", "");
        // insert a space after all groups of 4 digits that are followed by another digit
        processed = processed.replaceAll("(\\d{4})(?=\\d)", "$1 ");
        // to avoid stackoverflow errors, check that the processed is different from what's already
        //  there before setting
        if (!initial.equals(processed)) {
            // set the value
            s.replace(0, initial.length(), processed);
        }

    }

});


回答5:

I'm adding my solution to the list. As far as I am aware, it has no drawback; you can edit in the middle, delete spacing characters, copy and paste into it etc.

To allow editing to take place anywhere in the string, and to maintain cursor position, the Editable is traversed and all whitespace (if any) are taken out one by one. New whitespace is then added at appropriate positions. This will ensure that the cursor moves along with the changes made to the contents.

import java.util.LinkedList;


import android.text.Editable;
import android.text.TextWatcher;
import android.widget.EditText;


/**
 * Formats the watched EditText to groups of characters, with spaces between them.
 */
public class GroupedInputFormatWatcher implements TextWatcher {

    private static final char SPACE_CHAR = ' ';
    private static final String SPACE_STRING = String.valueOf(SPACE_CHAR);
    private static final int GROUPSIZE = 4;

    /**
     * Breakdown of this regexp:
     * ^             - Start of the string
     * (\\d{4}\\s)*  - A group of four digits, followed by a whitespace, e.g. "1234 ". Zero or more times.
     * \\d{0,4}      - Up to four (optional) digits.
     * (?<!\\s)$     - End of the string, but NOT with a whitespace just before it.
     * 
     * Example of matching strings:
     *  - "2304 52"
     *  - "2304"
     *  - ""
     */
    private final String regexp = "^(\\d{4}\\s)*\\d{0,4}(?<!\\s)$";
    private boolean isUpdating = false;

    private final EditText editText;

    public GroupedInputFormatWatcher(EditText editText) {
        this.editText = editText;
    }

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {

    }

    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {

    }

    @Override
    public void afterTextChanged(Editable s) {
        String originalString = s.toString();

        // Check if we are already updating, to avoid infinite loop.
        // Also check if the string is already in a valid format.
        if (isUpdating || originalString.matches(regexp)) {
            return;
        }

        // Set flag to indicate that we are updating the Editable.
        isUpdating = true;

        // First all whitespaces must be removed. Find the index of all whitespace.
        LinkedList<Integer> spaceIndices = new LinkedList <Integer>();
        for (int index = originalString.indexOf(SPACE_CHAR); index >= 0; index = originalString.indexOf(SPACE_CHAR, index + 1)) {
            spaceIndices.offerLast(index);
        }

        // Delete the whitespace, starting from the end of the string and working towards the beginning.
        Integer spaceIndex = null;
        while (!spaceIndices.isEmpty()) {
            spaceIndex = spaceIndices.removeLast();
            s.delete(spaceIndex, spaceIndex + 1);
        }

        // Loop through the string again and add whitespaces in the correct positions
        for(int i = 0; ((i + 1) * GROUPSIZE + i) < s.length(); i++) {
            s.insert((i + 1) * GROUPSIZE + i, SPACE_STRING);
        }

        // Finally check that the cursor is not placed before a whitespace.
        // This will happen if, for example, the user deleted the digit '5' in
        // the string: "1234 567".
        // If it is, move it back one step; otherwise it will be impossible to delete
        // further numbers.
        int cursorPos = editText.getSelectionStart();
        if (cursorPos > 0 && s.charAt(cursorPos - 1) == SPACE_CHAR) {
            editText.setSelection(cursorPos - 1);
        }

        isUpdating = false;
    }
}


回答6:

This implementation ensures correct placement of spacing chars, even if the user edits mid-string. Other characters that show up on the soft keyboard (such as dash) are also supported; that is, the user can't enter them. One improvement that could be made: this implementation doesn't allow for the deletion of spacing characters mid-string.

public class CreditCardTextWatcher implements TextWatcher {

    public static final char SPACING_CHAR = '-'; // Using a Unicode character seems to stuff the logic up.

    @Override
    public void beforeTextChanged(final CharSequence s, final int start, final int count, final int after) { }

    @Override
    public void onTextChanged(final CharSequence s, final int start, final int before, final int count) { }

    @Override
    public void afterTextChanged(final Editable s) {
        if (s.length() > 0) {

            // Any changes we make to s in here will cause this method to be run again.  Thus we only make changes where they need to be made,
            // otherwise we'll be in an infinite loop.

            // Delete any spacing characters that are out of place.
            for (int i=s.length()-1; i>=0; --i) {
                if (s.charAt(i) == SPACING_CHAR  // There is a spacing char at this position ,
                        && (i+1 == s.length()    // And it's either the last digit in the string (bad),
                        || (i+1) % 5 != 0)) {    // Or the position is not meant to contain a spacing char?

                    s.delete(i,i+1);
                }
            }

            // Insert any spacing characters that are missing.
            for (int i=14; i>=4; i-=5) {
                if (i < s.length() && s.charAt(i) != SPACING_CHAR) {
                    s.insert(i, String.valueOf(SPACING_CHAR));
                }
            }
        }
    }
}

Works well with an appropriate PasswordTransformationMethod implementation to mask CC digits.



回答7:

I just did the next implementation and works well for me, even with pasting and typing new text in any position of the EditText.

Gist file

/**
 * Text watcher for giving "#### #### #### ####" format to edit text.
 * Created by epool on 3/14/16.
 */
public class CreditCardFormattingTextWatcher implements TextWatcher {

    private static final String EMPTY_STRING = "";
    private static final String WHITE_SPACE = " ";
    private String lastSource = EMPTY_STRING;

    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
    }

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
    }

    @Override
    public void afterTextChanged(Editable s) {
        String source = s.toString();
        if (!lastSource.equals(source)) {
            source = source.replace(WHITE_SPACE, EMPTY_STRING);
            StringBuilder stringBuilder = new StringBuilder();
            for (int i = 0; i < source.length(); i++) {
                if (i > 0 && i % 4 == 0) {
                    stringBuilder.append(WHITE_SPACE);
                }
                stringBuilder.append(source.charAt(i));
            }
            lastSource = stringBuilder.toString();
            s.replace(0, s.length(), lastSource);
        }
    }

}

Usage: editText.addTextChangedListener(new CreditCardFormattingTextWatcher());



回答8:

Please look at this project . Android form edit text is an extension of EditText that brings data validation facilities to the edittext



回答9:

Not sure the TextWatcher is the right thing to use - we should use InputFilter

According to Android documentation, TextWatcher should be used for an external usage example : one [EditView] for password input + one [TextView] view which displays "weak", "strong", etc...

For Credit Card Format I am using InputFilter:

public class CreditCardInputFilter implements InputFilter {
    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
        if (dest != null & dest.toString().trim().length() > 24) return null;
        if (source.length() == 1 && (dstart == 4 || dstart == 9 || dstart == 14))
            return " " + new String(source.toString());
        return null; // keep original
    }
}

And combine with a length filter (Android SDK) :

mEditCardNumber.setFilters(new InputFilter[]{
     new InputFilter.LengthFilter(24),
     new CreditCardInputFilter(),
});

This handle the case when typing and removing a digit.

(!) But this does not handle the case for a copy/paste of an entire string, this one should be done in a different InputFilter class

Hope it helps !



回答10:

After searching a lot and not getting any satisfactory answer to meet my needs, I ended up writing my own function.

Here is an example to format entered credit card details based on the type of card being entered. Currently it takes care of Visa, MasterCard and American Express for the purpose of formatting.

    editTxtCardNumber.addTextChangedListener(new TextWatcher() {

        private boolean spaceDeleted;

        @Override
        public void onTextChanged(CharSequence s, int arg1, int arg2,
                int arg3) {

        }

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            CharSequence charDeleted = s.subSequence(start, start + count);
            spaceDeleted = " ".equals(charDeleted.toString());
        }

        @Override
        public void afterTextChanged(Editable editable) {

            if(editTxtCardNumber.getText().length() > 0 && editTxtCardNumber.getText().charAt(0) == '3') {
                editTxtCardNumber.setFilters(new InputFilter[] { new InputFilter.LengthFilter(Constants.MAX_LENGTH_CARD_NUMBER_AMEX) });

                editTxtCardNumber.removeTextChangedListener(this);
                int cursorPosition = editTxtCardNumber.getSelectionStart();
                String withSpaces = formatTextAmEx(editable);
                editTxtCardNumber.setText(withSpaces);
                editTxtCardNumber.setSelection(cursorPosition + (withSpaces.length() - editable.length()));

                if (spaceDeleted) {
                    editTxtCardNumber.setSelection(editTxtCardNumber.getSelectionStart() - 1);
                    spaceDeleted = false;
                }

                editTxtCardNumber.addTextChangedListener(this);
            } else if(editTxtCardNumber.getText().length() > 0 
                    && (editTxtCardNumber.getText().charAt(0) == '4' || editTxtCardNumber.getText().charAt(0) == '5')) {
                editTxtCardNumber.setFilters(new InputFilter[] { new InputFilter.LengthFilter(Constants.MAX_LENGTH_CARD_NUMBER_VISA_MASTERCARD) });

                editTxtCardNumber.removeTextChangedListener(this);
                int cursorPosition = editTxtCardNumber.getSelectionStart();
                String withSpaces = formatTextVisaMasterCard(editable);
                editTxtCardNumber.setText(withSpaces);
                editTxtCardNumber.setSelection(cursorPosition + (withSpaces.length() - editable.length()));

                if (spaceDeleted) {
                    editTxtCardNumber.setSelection(editTxtCardNumber.getSelectionStart() - 1);
                    spaceDeleted = false;
                }

                editTxtCardNumber.addTextChangedListener(this);
            } else {
                editTxtCardNumber.setFilters(new InputFilter[] { new InputFilter.LengthFilter(Constants.MAX_LENGTH_CARD_NUMBER_VISA_MASTERCARD) });

                editTxtCardNumber.removeTextChangedListener(this);
                int cursorPosition = editTxtCardNumber.getSelectionStart();
                String withSpaces = formatTextVisaMasterCard(editable);
                editTxtCardNumber.setText(withSpaces);
                editTxtCardNumber.setSelection(cursorPosition + (withSpaces.length() - editable.length()));

                if (spaceDeleted) {
                    editTxtCardNumber.setSelection(editTxtCardNumber.getSelectionStart() - 1);
                    spaceDeleted = false;
                }

                editTxtCardNumber.addTextChangedListener(this);
            }
        }
    });

    private String formatTextVisaMasterCard(CharSequence text)
    {
        StringBuilder formatted = new StringBuilder();
        int count = 0;
        for (int i = 0; i < text.length(); ++i)
        {
            if (Character.isDigit(text.charAt(i)))
            {
                if (count % 4 == 0 && count > 0)
                    formatted.append(" ");
                formatted.append(text.charAt(i));
                ++count;
            }
        }
        return formatted.toString();
    }

    private String formatTextAmEx(CharSequence text)
    {
        StringBuilder formatted = new StringBuilder();
        int count = 0;
        for (int i = 0; i < text.length(); ++i)
        {
            if (Character.isDigit(text.charAt(i)))
            {
                if (count > 0 && ((count == 4) || (count == 10))) {
                    formatted.append(" ");
                }
                formatted.append(text.charAt(i));
                ++count;
            }
        }
        return formatted.toString();
    }

Other than formatting spaces, I also applied checks to make sure that card number doesn't exceed their maximum limit and user gets notified that he has entered all the digits by performing a change in font when the maximum limit is reached. Here is the function to perform the above mentioned operation.

public void checkCardNoEnteredCorrectly() {
if(editTxtCardNumber.getText().length() > 0 && editTxtCardNumber.getText().charAt(0) == '3') {
    if(editTxtCardNumber.getText().length() == Constants.MAX_LENGTH_CARD_NUMBER_AMEX) {
        editTxtCardNumber.setCompoundDrawablesWithIntrinsicBounds(getResources().getDrawable(R.drawable.amex), null, null, null);
    } else {
        editTxtCardNumber.setCompoundDrawablesWithIntrinsicBounds(getResources().getDrawable(R.drawable.amex), null, null, null);
    }
} else if(editTxtCardNumber.getText().length() > 0 && editTxtCardNumber.getText().charAt(0) == '4') {
    if(editTxtCardNumber.getText().length() == Constants.MAX_LENGTH_CARD_NUMBER_VISA_MASTERCARD) {
        editTxtCardNumber.setCompoundDrawablesWithIntrinsicBounds(getResources().getDrawable(R.drawable.visa), null, null, null);
    } else {
        editTxtCardNumber.setCompoundDrawablesWithIntrinsicBounds(getResources().getDrawable(R.drawable.visa), null, null, null);
    }
} else if(editTxtCardNumber.getText().length() > 0 && editTxtCardNumber.getText().charAt(0) == '5') {
    if(editTxtCardNumber.getText().length() == Constants.MAX_LENGTH_CARD_NUMBER_VISA_MASTERCARD) {
        editTxtCardNumber.setCompoundDrawablesWithIntrinsicBounds(getResources().getDrawable(R.drawable.master_card), null, null, null);
    } else {
        editTxtCardNumber.setCompoundDrawablesWithIntrinsicBounds(getResources().getDrawable(R.drawable.master_card), null, null, null);
    }
} else {
    editTxtCardNumber.setCompoundDrawablesWithIntrinsicBounds(getResources().getDrawable(R.drawable.credit_card_number), null, null, null);
}

}

Note: The declarations made in Constants.java is as follows:

public static final int MAX_LENGTH_CARD_NUMBER_VISA_MASTERCARD = 19;
public static final int MAX_LENGTH_CARD_NUMBER_AMEX = 17;

Hope it helps!



回答11:

You may have figured it out already, but here is what I did. The only method I had to override was AfterTextChanged.

Check if the form of the credit card is already valid, base case to prevent infinite recursion

If the form is not valid, remove all whitespace, and copy over into another string, inserting white space where appropriate.

Then simply replace the editable with your new string.

If you need code for a particular step, feel free to ask.

And Preethi, the reason you can't delete spaces is because you can't change text in the onTextChanged callback. From the developer site:

public abstract void onTextChanged (CharSequence s, int start, int before, int count) Added in API level 1

This method is called to notify you that, within s, the count characters beginning at start have just replaced old text that had length before. It is an error to attempt to make changes to s from this callback.



回答12:

int          keyDel;
String       a;
String       a0;
int          isAppent = 0;
final String ch       = " ";

private void initListner() {


    txtCreditNumber.addTextChangedListener(new TextWatcher() {

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {

            boolean flag = true;
            if (s.length() > 19) {
                txtCreditNumber.setText(a0);
                txtCreditNumber.setSelection(txtCreditNumber.getText().length());
                return;
            }
            String eachBlock[] = s.toString().split(ch);
            for(int i = 0; i < eachBlock.length; i++) {
                if (eachBlock[i].length() > 4) {
                    flag = false;
                }
            }
            if (a0.length() > s.toString().length()) {
                keyDel = 1;
            }
            if (flag) {
                if (keyDel == 0) {

                    if (((txtCreditNumber.getText().length() + 1) % 5) == 0) {

                        if (s.toString().split(ch).length <= 3) {
                            isAppent = 1;
                            txtCreditNumber.setText(s + ch);
                            isAppent = 0;
                            txtCreditNumber.setSelection(txtCreditNumber.getText().length());
                            a = txtCreditNumber.getText().toString();
                            return;
                        }
                    }
                    if (isAppent == 0) {
                        String str = s.toString();
                        if (str.lastIndexOf(ch) == str.length() - 1) {
                            str = str.substring(0, str.lastIndexOf(ch));
                            keyDel = 1;
                            txtCreditNumber.setText(str);
                            keyDel = 0;
                            txtCreditNumber.setSelection(txtCreditNumber.getText().length());
                            a = txtCreditNumber.getText().toString();
                            return;
                        }
                    }

                }
                else {
                    String str = s.toString();
                    if (str.length() > 0 && str.lastIndexOf(ch) == str.length() - 1) {
                        str = str.substring(0, str.lastIndexOf(ch));
                        keyDel = 1;
                        txtCreditNumber.setText(str);
                        keyDel = 0;
                        txtCreditNumber.setSelection(txtCreditNumber.getText().length());
                        a = txtCreditNumber.getText().toString();
                        return;
                    }
                    else {
                        a = txtCreditNumber.getText().toString();
                        keyDel = 0;
                    }
                }

            }
            else {
                String str = s.toString();
                str = str.substring(0, str.length() - 1) + ch + str.substring(str.length() - 1, str.length());

                a = str;
                txtCreditNumber.setText(a);
                txtCreditNumber.setSelection(txtCreditNumber.getText().length());
            }

        }

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            // TODO Auto-generated method stub
            a0 = s.toString();
        }

        @Override
        public void afterTextChanged(Editable s) {
        }
    });
}


回答13:

Here is an example that use all the function appropriately to make a decision. The code might be a bit longer, but it will be faster as it mainly use the function given values (start, before, count ...). This example add "-" every 4 digits, and delete them as well, when user use backspace. as well, make sure the cursor will be at the end.

public class TextWatcherImplement implements TextWatcher {

private EditText creditCard;
private String beforeText, currentText;
private boolean noAction, addStroke, dontAddChar, deleteStroke;

public TextWatcherImplement(EditText creditCard) {
    // TODO Auto-generated constructor stub
    this.creditCard = creditCard;
    noAction = false;
    addStroke = false;
    dontAddChar = false;
    deleteStroke = false;
}

/* here I save the previous string if the max character had achieved */
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
    // TODO Auto-generated method stub
    Log.i("TextWatcherImplement", "beforeTextChanged start==" + String.valueOf(start) + " count==" + String.valueOf(count) + " after==" + String.valueOf(after));
    if (start >= 19)
        beforeText = s.toString();
}


/* here I check were we add a character, or delete one. 
if we add character and it is time to add a stroke, then I flag it -> addStroke 
if we delete a character and it time to delete a stroke, I flag it -> deleteStroke
if we are in max character for the credit card, don't add char -> dontAddChar 
*/
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
    // TODO Auto-generated method stub
    Log.i("TextWatcherImplement", "onTextChanged start==" + String.valueOf(start) + " before==" + String.valueOf(before) + " count==" + String.valueOf(count) + " noAction ==" + String.valueOf(noAction));
    if ( (before < count) && !noAction ) {
        if ( (start == 3) || (start == 8) || (start == 13) ) {
            currentText = s.toString();
            addStroke = true;
        } else if (start >= 19) {
            currentText = s.toString();
            dontAddChar = true;
        }
    } else {
        if ( (start == 4) ||  (start == 9) ||  (start == 14)  ) { //(start == 5) || (start == 10) || (start == 15)
            currentText = s.toString();
            deleteStroke = true;
        }
    }
}

/* noAction flag is when we change the text, the interface is being called again.
the NoAction flag will prevent any action, and prevent a ongoing loop */

@Override
public void afterTextChanged(Editable stext) {
    // TODO Auto-generated method stub
    if (addStroke) {
        Log.i("TextWatcherImplement", "afterTextChanged String == " + stext + " beforeText == " + beforeText + " currentText == " + currentText);
        noAction = true;
        addStroke = false;
        creditCard.setText(currentText + "-");
    } else if (dontAddChar) {
        dontAddChar = false;
        noAction = true;
        creditCard.setText(beforeText);
    } else if (deleteStroke) {
        deleteStroke = false;
        noAction = true;
        currentText = currentText.substring(0, currentText.length() - 1);
        creditCard.setText(currentText);
    } else {
        noAction = false;
        creditCard.setSelection(creditCard.getText().length()); // set cursor at the end of the line.
    }
}

}



回答14:

Here's my solution. My comments should suffice enough information for an Android developer to understand what's happening but if you have any questions then please feel free to ask and I'll answer to the best of my knowledge.

private KeyEvent keyEvent;

final TextWatcher cardNumberWatcher = new TextWatcher() {
        @Override
        public void beforeTextChanged(CharSequence charSequence, int start, int before, int count) {
            // NOT USING
        }

        @Override
        public void onTextChanged(CharSequence charSequence, int start, int before, int count) {
            // NOT USING
        }

        @Override
        public void afterTextChanged(Editable editable) {
            String cardNumbersOnly = editable.toString().replace("-", "");

            /**
            * @PARAM keyEvent
            * This gets called upon deleting a character so you must keep a 
            * flag to ensures this gets skipped during character deletion
            */
            if (cardNumbersOnly.length() >= 4 && keyEvent == null) {
                formatCreditCardTextAndImage(this);
            }

            keyEvent = null;
        }
    };

    cardNumberEditText.addTextChangedListener(cardNumberWatcher);

    /**
    * @LISTENER
    * Must keep track of when the backspace event has been fired to ensure    
    * that the delimiter character and the character before it is deleted 
    * consecutively to avoid the user from having to press backspace twice 
    */
    cardNumberEditText.setOnKeyListener(new View.OnKeyListener() {
        @Override
        public boolean onKey(View v, int keyCode, KeyEvent event) {
            if (event.getAction() != KeyEvent.ACTION_UP) {
                // Hold reference of key event for checking within the text watcher
                keyEvent = event;
                String cardNumberString = cardNumberEditText.getText().toString();

                if (keyCode == event.KEYCODE_DEL) {
                    if (cardNumberString.substring(cardNumberString.length() - 1).equals("-")) {
                        // Remove listener to avoid infinite looping
                        cardNumberEditText.removeTextChangedListener(cardNumberWatcher);
                        // Remove hyphen and character before it
                        cardNumberEditText.setText(cardNumberString.substring(0, cardNumberString.length() - 1));
                        // Set the cursor back to the end of the text
                        cardNumberEditText.setSelection(cardNumberEditText.getText().length());
                        // Add the listener back
                        cardNumberEditText.addTextChangedListener(cardNumberWatcher);
                    }
                    else if (cardNumberString.length() < 2) {
                        cardNumberBrandImageView.setImageDrawable(null);
                        cardNumberBrandImageView.setVisibility(View.INVISIBLE);
                    }
                }
            }
            return false;
        }
    });
}

private void formatCreditCardTextAndImage (TextWatcher textWatcher) {
    // Remove to avoid infinite looping
    cardNumberEditText.removeTextChangedListener(textWatcher);

    String cardNumberString = cardNumberEditText.getText().toString();

    /**
    * @CONDITION
    * Append delimiter after every fourth character excluding the 16th
    */
    if ((cardNumberString.length() + 1) % 5 == 0 && !cardNumberString.substring(cardNumberString.length() - 1).equals("-")) {
            cardNumberEditText.setText(cardNumberString + "-");
    }

    // Set the cursor back to the end of the text
    cardNumberEditText.setSelection(cardNumberEditText.getText().length());
    cardNumberEditText.addTextChangedListener(textWatcher);

    /**
    * @CardBrand
    * Is an enum utility class that checks the card numbers 
    * against regular expressions to determine the brand and updates the UI
    */
    if (cardNumberString.length() == 2) {
        switch (CardBrand.detect(cardNumberEditText.getText().toString())) {
            case VISA:
                cardNumberBrandImageView.setImageResource(R.drawable.visa);
                cardNumberBrandImageView.setVisibility(View.VISIBLE);
                card.setBrand(Brand.Visa);
                break;
            case MASTERCARD:
                cardNumberBrandImageView.setImageResource(R.drawable.mastercard);
                cardNumberBrandImageView.setVisibility(View.VISIBLE);
                card.setBrand(Brand.MasterCard);
                break;
            case DISCOVER:
                cardNumberBrandImageView.setImageResource(R.drawable.discover);
                cardNumberBrandImageView.setVisibility(View.VISIBLE);
                card.setBrand(Brand.Discover);
                break;
            case AMERICAN_EXPRESS:
                cardNumberBrandImageView.setImageResource(R.drawable.americanexpress);
                cardNumberBrandImageView.setVisibility(View.VISIBLE);
                card.setBrand(Brand.AmericanExpress);
                break;
            case UNKNOWN:
                cardNumberBrandImageView.setImageDrawable(null);
                cardNumberBrandImageView.setVisibility(View.INVISIBLE);
                card.setBrand(null);
                break;
        }
    }
}


回答15:

Here's a simple and easily customizable solution using the TextWatcher class. It may be assigned to your EditText using the addTextChangedListener() method.

new TextWatcher() {
    /** Formats the Field to display user-friendly separation of the input values. */
    @Override public final void afterTextChanged(final Editable pEditable) {
        // Declare the separator.
        final char lSeparator      = '-';
        // Declare the length of separated text. i.e. (XXXX-XXXX-XXXX)
        final int  lSeparationSize = 4;
        // Declare the count; tracks the number of allowed characters in a row.
              int lCount          = 0;
        // Iterate the Characters.
        for(int i = 0; i < pEditable.length(); i++) {
            // Fetch the current character.
            final char c              = pEditable.charAt(i);
            // Is it a usual character. Here, we permit alphanumerics only.
            final boolean lIsExpected = (Character.isDigit(c) || Character.isLetter(c)) && (c != lSeparator);
            // Is the character expected?
            if(lIsExpected) {
                // Increase the count.
                lCount++;
            }
            else {
                // Is it a separator?
                if(c == lSeparator) {
                    // Reset the count.
                    lCount = 0;
                    // Continue the iteration.
                    continue;
                }
            }
            // Has the count been exceeded? Is there more text coming?
            if(lCount >= (lSeparationSize + 1) && (i < pEditable.length())) {
                // Reset the count.
                lCount = 0;
                // Insert the separator.
                pEditable.insert(i, Character.toString(lSeparator));
                // Increase the iteration count.
                i++;
            }
        }
    }
    /** Unused overrides. */
    @Override public final void beforeTextChanged(final CharSequence pCharSequence, final int pStart, final int pCount, final int pAfter) { }
    @Override public final void onTextChanged(final CharSequence pCharSequence, final int pStart, final int pBefore, final int pCount) { }
}

Alternatively, here is a much cleaner implementation based on epool's implementation.

public final class TextGroupFormattingListener implements TextWatcher {

    /* Member Variables. */
    private final int    mGroupLength;
    private final String mSeparator;
    private       String mSource;

    /** Constructor. */
    public TextGroupFormattingListener(final String pSeparator, final int pGroupLength) {
        // Initialize Member Variables.
        this.mSeparator   = pSeparator;
        this.mGroupLength = pGroupLength;
        this.mSource      = "";
    }

    /** Formats the Field to display user-friendly separation of the input values. */
    @Override public final void afterTextChanged(final Editable pEditable) {
        // Fetch the Source.
        String lSource = pEditable.toString();
        // Has the text changed?
        if (!this.getSource().equals(lSource)) {
            // Remove all of the existing Separators.
            lSource = lSource.replace(this.getSeparator(), "");
            // Allocate a StringBuilder.
            StringBuilder lStringBuilder = new StringBuilder();
            // Iterate across the Source String, which contains the raw user input.
            for(int i = 0; i < lSource.length(); i++) {
                // Have we exceeded the GroupLength?
                if(i > 0 && i % this.getGroupLength() == 0) {
                    // Append the separator.
                    lStringBuilder.append(this.getSeparator());
                }
                // Append the user's character data.
                lStringBuilder.append(lSource.charAt(i));
            }
            // Track changes to the Source.
            this.setSource(lStringBuilder.toString());
            // Replace the contents of the Editable with this new String.
            pEditable.replace(0, pEditable.length(), this.getSource());
        }
    }

    /** Unused overrides. */
    @Override public final void beforeTextChanged(final CharSequence pCharSequence, final int pStart, final int pCount, final int pAfter) { }
    @Override public final void onTextChanged(final CharSequence pCharSequence, final int pStart, final int pBefore, final int pCount)    { }

    public final int getGroupLength() {
        return this.mGroupLength;
    }

    public final String getSeparator() {
        return this.mSeparator;
    }

    private final void setSource(final String pSource) {
        this.mSource = pSource;
    }

    private final String getSource() {
        return this.mSource;
    }

}


回答16:

I think that my solution can work well whatever middle text operation or copy-paste operation.

Please see code as below,

  class BankNumberTextWatcher implements TextWatcher {
      private int previousCodeLen = 0;

      @Override
      public void beforeTextChanged(CharSequence s, int start, int count, int after) {
      }

      @Override
      public void onTextChanged(CharSequence s, int start, int before, int count) {
      }

      @Override
      public void afterTextChanged(Editable s) {
          if (s.length() > 0) {
              String numbersOnly = s.toString().replaceAll("[^0-9]", "");
              // current code pattern miss-match, then handle cursor position and format the code
              handleEditInput(numbersOnly);
          } else {
              previousCodeLen = 0;
          }
      }

      /**
       * Handle EditText input process for credit card including insert, delete during middle position,
       * end position or copy-paste controller
       *
       * @param numbersOnly the pure number without non-digital characters
       */
      private void handleEditInput(final String numbersOnly) {
          String code = formatNumbersAsCode(numbersOnly);
          int cursorStart = etBankCardNumber.getSelectionStart();
          etBankCardNumber.removeTextChangedListener(this);
          etBankCardNumber.setText(code);
          int codeLen = code.length();
          if (cursorStart != codeLen) {
             // middle-string operation
             if (cursorStart > 0 && cursorStart % 5 == 0) {
                if (codeLen > previousCodeLen) {
                    // insert, move cursor to next
                    cursorStart++;
                } else if (codeLen < previousCodeLen) {
                    // delete, move cursor to previous
                    cursorStart--;
                }
             }
             etBankCardNumber.setSelection(cursorStart);
          } else {
             // end-string operation
             etBankCardNumber.setSelection(codeLen);
          }
          etBankCardNumber.addTextChangedListener(this);
          previousCodeLen = codeLen;
      }

      /**
       * formats credit code like 1234 1234 5123 1234
       *
       * @param s
       * @return
       */
       public String formatNumbersAsCode(CharSequence s) {
          if (TextUtils.isEmpty(s)) {
            return "";
          }
          int len = s.length();
          StringBuilder tmp = new StringBuilder();
          for (int i = 0; i < len; ++i) {
              tmp.append(s.charAt(i));
              if ((i + 1) % 4 == 0 && (i + 1) != len) {
                  tmp.append(" ");
              }
          }
          return tmp.toString();
        }
  }

Makes inputType to number for EditText to avoid other characters in the layout file.

Hope that be helpful for you.



回答17:

None of above answers is perfect for me. I created one that solves the start-string/end-string/mid-string issues. Copy & Paste should also work fine. This supports Mastercard, Visa and Amex. You can change the separator. If you don't need payment method type just remove it. It is Kotlin though. The idea is simple. Everytime when text changed I remove all separators and re-added them base on the format. The solves the issue start-string/mid-string issues. Then the only problem is that you need to work out the the right text position after separators added.

fun addCreditCardNumberTxtWatcher(et: EditText, separator: Char, paymentMethodType: PaymentMethodType): TextWatcher {
    val tw = object : TextWatcher {
        var mBlock = false
        override fun afterTextChanged(s: Editable) {
        }
        override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {
              Logger.d("_debug", "s: $s, start: $start, count: $count, after $after")
        }
        override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
            if (mBlock)
                return
            var lastPos = et.selectionStart
            val oldStr = et.text.toString().replace(separator.toString(), "", false)
            var newFormattedStr = ""
            if (before > 0) {
                if (lastPos > 0 && et.text.toString()[lastPos - 1] == separator) lastPos--
            }
            Logger.d("_debug", "lastPos: $lastPos, s: $s, start: $start, before: $before, count $count")
            mBlock = true
            oldStr.forEachIndexed { i, c ->
                when (paymentMethodType) {
                    PaymentMethodType.MASTERCARD, PaymentMethodType.VISA -> {
                        if (i > 0 && i % 4 == 0) {
                            newFormattedStr += separator
                        }
                    }
                    PaymentMethodType.AMERICAN_EXPRESS -> {
                        if (i == 4 || i == 10 || i == 15) {
                            newFormattedStr += separator
                        }
                    }
                }
                newFormattedStr += c
            }
            et.setText(newFormattedStr)
            if (before == 0) {
                if (et.text.toString()[lastPos - 1] == separator) lastPos++
            }
            et.setSelection(lastPos)
            mBlock = false
        }
    }
    et.addTextChangedListener(tw)
    return tw
}


回答18:

This solution was implemented for IBAN's but the principle is the same, I tried to correct all the main problems in the answers above, if you find an error feel free to say it, thank you.

Set the EditText and restrict the characters that can be used:

private void setEditTextIBAN(View view) {
    editTextIBAN = (EditText) view.findViewById(R.id.client_iban);
    editTextIBAN.setKeyListener(
            DigitsKeyListener.getInstance("ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890 "));
    editTextIBAN.addTextChangedListener(new IBANTextWatcher());
}

This is the TextWatcher:

private class IBANTextWatcher implements TextWatcher {

    // means divider position is every 5th symbol
    private static final int DIVIDER_MODULO = 5;
    private static final int GROUP_SIZE = DIVIDER_MODULO - 1;
    private static final char DIVIDER = ' ';
    private static final String STRING_DIVIDER = " ";
    private String previousText = "";

    private int deleteLength;
    private int insertLength;
    private int start;

    private String regexIBAN = "(\\w{" + GROUP_SIZE + "}" + DIVIDER +
            ")*\\w{1," + GROUP_SIZE + "}";
    private Pattern patternIBAN = Pattern.compile(regexIBAN);

    @Override
    public void beforeTextChanged(final CharSequence s, final int start, final int count, final int after) {
        this.previousText = s.toString();
        this.deleteLength = count;
        this.insertLength = after;
        this.start = start;
    }

    @Override
    public void onTextChanged(final CharSequence s, final int start, final int before, final int count) {

    }

    @Override
    public void afterTextChanged(final Editable s) {
        String originalString = s.toString();

        if (!previousText.equals(originalString) &&
                !isInputCorrect(originalString)) {
            String newString = previousText.substring(0, start);
            int cursor = start;

            if (deleteLength > 0 && s.length() > 0 &&
                    (previousText.charAt(start) == DIVIDER ||
                            start == s.length())) {
                newString = previousText.substring(0, start - 1);
                --cursor;
            }

            if (insertLength > 0) {
                newString += originalString.substring(start, start + insertLength);
                newString = buildCorrectInput(newString);
                cursor = newString.length();
            }

            newString += previousText.substring(start + deleteLength);
            s.replace(0, s.length(), buildCorrectInput(newString));

            editTextIBAN.setSelection(cursor);
        }
    }

    /**
     * Check if String has the white spaces in the correct positions, meaning
     * if we have the String "123456789" and there should exist a white space
     * every 4 characters then the correct String should be "1234 5678 9".
     *
     * @param s String to be evaluated
     * @return true if string s is written correctly
     */
    private boolean isInputCorrect(String s) {
        Matcher matcherDot = patternIBAN.matcher(s);
        return matcherDot.matches();
    }

    /**
     * Puts the white spaces in the correct positions,
     * see the example in {@link IBANTextWatcher#isInputCorrect(String)}
     * to understand the correct positions.
     *
     * @param s String to be corrected.
     * @return String corrected.
     */
    private String buildCorrectInput(String s) {
        StringBuilder sbs = new StringBuilder(
                s.replaceAll(STRING_DIVIDER, ""));

        // Insert the divider in the correct positions
        for (int i = GROUP_SIZE; i < sbs.length(); i += DIVIDER_MODULO) {
            sbs.insert(i, DIVIDER);
        }

        return sbs.toString();
    }
}


回答19:

In your layout:

    <android.support.design.widget.TextInputEditText
        android:id="@+id/et_credit_card_number"
        android:digits=" 1234567890"
        android:inputType="number"
        android:maxLength="19"/>

Here the TextWachter which sets a space on every 4 digits in a 16 number credit card.

class CreditCardFormatWatcher : TextWatcherAdapter() {

    override fun afterTextChanged(s: Editable?) {
        if (s == null || s.isEmpty()) return

        s.forEachIndexed { index, c ->
            val spaceIndex = index == 4 || index == 9 || index == 14
            when {
                !spaceIndex && !c.isDigit()     -> s.delete(index, index + 1)
                spaceIndex && !c.isWhitespace() -> s.insert(index, " ")
            }
        }

        if (s.last().isWhitespace())
            s.delete(s.length - 1, s.length)
    }

}


回答20:

 private class TextWatcherIBAN implements TextWatcher {

        @Override
        public void beforeTextChanged(CharSequence s, int start, int count, int after) {

        }

        @Override
        public void onTextChanged(CharSequence s, int start, int before, int count) {

        }

        @Override
        public void afterTextChanged(Editable s) {
            textInputEditText.removeTextChangedListener(this);
            formatIBANEditText(textInputEditText);
            textInputEditText.addTextChangedListener(this);

        }
    }


public void formatIBANEditText(TextInputEditText editText) {
    String decimalAmount = editText.getText().toString();
    int selection = editText.getSelectionEnd() == decimalAmount.length() ? -1 : editText.getSelectionEnd();
    decimalAmount = formatIBAN(decimalAmount);
    editText.setText(decimalAmount);

    if (selection != -1) {
        editText.setSelection(selection);
    } else {
        editText.setSelection(decimalAmount.length());
    }

}

public String formatIBAN(String text) {
    return formatterIBAN(new StringBuilder(text));
}

private String formatterIBAN(StringBuilder text) {
    int group = text.toString().length() / 5;
    int spaceCount = getSpaceCount(text);
    if (spaceCount < group) {
        return formatterIBAN(text.insert(4 + 5 * spaceCount, space));
    } else {
        return text.toString();
    }
}

private int getSpaceCount(StringBuilder text) {
    int spaceCount = 0;
    for (int index = 0; index < text.length(); index++) {
        if (text.charAt(index) == space.charAt(0)) {
            spaceCount++;
        }
    }
    return spaceCount;
}


textInputEditText.addTextChangedListener(new TextWatcherIBAN());


回答21:

class XYZ : TextWatcher {

private val formatSymbols = DecimalFormatSymbols(Locale.getDefault())

private lateinit var formatter: DecimalFormat

override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
    .
    .
    formatSymbols.groupingSeparator = ' '
    formatter = DecimalFormat("####,####", formatSymbols)
    .
    .
}

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)
    editText.addTextChangedListener(this)
}

override fun afterTextChanged(s: Editable?) {
    if (editText.error != null) {
        editText.error = null
    }
    editText.removeTextChangedListener(this)
    try {
        var originalString = s.toString()
        if (originalString.contains(" ")) {
            originalString = originalString.replace(" ", "", true)
        }
        val longVal: Long? = originalString.toLong()
        val formattedString = formatter.format(longVal)
        editText.setText(formattedString)
        editText.setSelection(editText.text.length)
    } catch (error: NumberFormatException) {
        // Print Error Or Do Whatever you want.
    }
    editText.addTextChangedListener(this)
}

}