How to mask an EditText to show the dd/mm/yyyy dat

问题:

How can I format an EditText to follow the "dd/mm/yyyy" format the same way that we can format using a TextWatcher to mask the user input to look like "0.05€". I'm not talking about limiting the characters, or validating a date, just masking to the previous format.

回答1:

I wrote this TextWatcher for a project, hopefully it will be helpful to someone. Note that it does not validate the date entered by the user, and you should handle that when the focus changes, since the user may not have finished entering the date.

Update 25/06 Made it a wiki to see if we reach a better final code.

Update 07/06 I finally added some sort of validation to the watcher itself. It will do the following with invalid dates:

• If the month is greater than 12, it will be 12 (December)
• If the date is greater than the one for the month selected, make it the max for that month.
• If the year is not in the range 1900-2100, change it to be in the range

This validation fits my needs, but some of you may want to change it a little bit, ranges are easily changeable and you could hook this validations to Toast message for instance, to notify the user that we've modified his/her date since it was invalid.

In this code, I will be assuming that we have a reference to our EditText called date that has this TextWatcher attached to it, this can be done something like this:

EditText date;
date = (EditText)findViewById(R.id.whichdate);
date.addTextChangedListener(tw);

---

TextWatcher tw = new TextWatcher() {
    private String current = "";
    private String ddmmyyyy = "DDMMYYYY";
    private Calendar cal = Calendar.getInstance();

When user changes text of the EditText

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {
        if (!s.toString().equals(current)) {
            String clean = s.toString().replaceAll("[^\\d.]|\\.", "");
            String cleanC = current.replaceAll("[^\\d.]|\\.", "");

            int cl = clean.length();
            int sel = cl;
            for (int i = 2; i <= cl && i < 6; i += 2) {
                sel++;
            }
            //Fix for pressing delete next to a forward slash
            if (clean.equals(cleanC)) sel--;

            if (clean.length() < 8){
               clean = clean + ddmmyyyy.substring(clean.length());
            }else{
               //This part makes sure that when we finish entering numbers
               //the date is correct, fixing it otherwise
               int day  = Integer.parseInt(clean.substring(0,2));
               int mon  = Integer.parseInt(clean.substring(2,4));
               int year = Integer.parseInt(clean.substring(4,8));

               mon = mon < 1 ? 1 : mon > 12 ? 12 : mon;
               cal.set(Calendar.MONTH, mon-1);
               year = (year<1900)?1900:(year>2100)?2100:year;
               cal.set(Calendar.YEAR, year); 
               // ^ first set year for the line below to work correctly
               //with leap years - otherwise, date e.g. 29/02/2012
               //would be automatically corrected to 28/02/2012 

               day = (day > cal.getActualMaximum(Calendar.DATE))? cal.getActualMaximum(Calendar.DATE):day;
               clean = String.format("%02d%02d%02d",day, mon, year);
            }

            clean = String.format("%s/%s/%s", clean.substring(0, 2),
                clean.substring(2, 4),
                clean.substring(4, 8));

            sel = sel < 0 ? 0 : sel;
            current = clean;
            date.setText(current);
            date.setSelection(sel < current.length() ? sel : current.length());
        }
    }

We also implement the other two functions because we have to

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

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

This produces the following effect, where deleting or inserting characters will reveal or hide the dd/mm/yyyy mask. It should be easy to modify to fit other format masks since I tried to leave the code as simple as possible.

回答2:

The current answer is very good and helped guide me towards my own solution. There are a few reasons why I decided to post my own solution even though this question already has a valid answer:

• I´m working in Kotlin, not Java. People who find themselves with the same issue will have to translate the current solution.
• I wanted to write an answer that was more legible so that people can more easily adapt it to their own problems.
• As suggested by dengue8830, I encapsulated the solution to this problem in a class, so anyone can use without even worrying about the implementation.

To use it, just do something like:

• DateInputMask(mEditText).listen()

And the solution is shown below:

class DateInputMask(val input : EditText) {

    fun listen() {
        input.addTextChangedListener(mDateEntryWatcher)
    }

    private val mDateEntryWatcher = object : TextWatcher {

        var edited = false
        val dividerCharacter = "/"

        override fun onTextChanged(s: CharSequence, start: Int, before: Int, count: Int) {
            if (edited) {
                edited = false
                return
            }

            var working = getEditText()

            working = manageDateDivider(working, 2, start, before)
            working = manageDateDivider(working, 5, start, before)

            edited = true
            input.setText(working)
            input.setSelection(input.text.length)
        }

        private fun manageDateDivider(working: String, position : Int, start: Int, before: Int) : String{
            if (working.length == position) {
                return if (before <= position && start < position)
                    working + dividerCharacter
                else
                    working.dropLast(1)
            }
            return working
        }

        private fun getEditText() : String {
            return if (input.text.length >= 10)
                input.text.toString().substring(0,10)
            else
                input.text.toString()
        }

        override fun afterTextChanged(s: Editable) {}
        override fun beforeTextChanged(s: CharSequence, start: Int, count: Int, after: Int) {}
    }
}

回答3:

a cleaner way to use the Juan Cortés's code is put it in a class:

public class DateInputMask implements TextWatcher {

private String current = "";
private String ddmmyyyy = "DDMMYYYY";
private Calendar cal = Calendar.getInstance();
private EditText input;

public DateInputMask(EditText input) {
    this.input = input;
    this.input.addTextChangedListener(this);
}

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

}

@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
    if (s.toString().equals(current)) {
        return;
    }

    String clean = s.toString().replaceAll("[^\\d.]|\\.", "");
    String cleanC = current.replaceAll("[^\\d.]|\\.", "");

    int cl = clean.length();
    int sel = cl;
    for (int i = 2; i <= cl && i < 6; i += 2) {
        sel++;
    }
    //Fix for pressing delete next to a forward slash
    if (clean.equals(cleanC)) sel--;

    if (clean.length() < 8){
        clean = clean + ddmmyyyy.substring(clean.length());
    }else{
        //This part makes sure that when we finish entering numbers
        //the date is correct, fixing it otherwise
        int day  = Integer.parseInt(clean.substring(0,2));
        int mon  = Integer.parseInt(clean.substring(2,4));
        int year = Integer.parseInt(clean.substring(4,8));

        mon = mon < 1 ? 1 : mon > 12 ? 12 : mon;
        cal.set(Calendar.MONTH, mon-1);
        year = (year<1900)?1900:(year>2100)?2100:year;
        cal.set(Calendar.YEAR, year);
        // ^ first set year for the line below to work correctly
        //with leap years - otherwise, date e.g. 29/02/2012
        //would be automatically corrected to 28/02/2012

        day = (day > cal.getActualMaximum(Calendar.DATE))? cal.getActualMaximum(Calendar.DATE):day;
        clean = String.format("%02d%02d%02d",day, mon, year);
    }

    clean = String.format("%s/%s/%s", clean.substring(0, 2),
            clean.substring(2, 4),
            clean.substring(4, 8));

    sel = sel < 0 ? 0 : sel;
    current = clean;
    input.setText(current);
    input.setSelection(sel < current.length() ? sel : current.length());
}

@Override
public void afterTextChanged(Editable s) {

}
}

then you can reuse it

new DateInputMask(myEditTextInstance);

回答4:

This answer does not apply a full mask for the remaining untyped digits. However, it is related and is the solution I needed. It works similar to how PhoneNumberFormattingTextWatcher works.

As you type it adds slashes to separate a date formatted like mm/dd/yyyy. It does not do any validation - just formatting.

No need for an EditText reference. Just set the listener and it works. myEditText.addTextChangedListener(new DateTextWatcher());

import android.text.Editable;
import android.text.TextWatcher;

import java.util.Locale;

/**
 * Adds slashes to a date so that it matches mm/dd/yyyy.
 *
 * Created by Mark Miller on 12/4/17.
 */
public class DateTextWatcher implements TextWatcher {

    public static final int MAX_FORMAT_LENGTH = 8;
    public static final int MIN_FORMAT_LENGTH = 3;

    private String updatedText;
    private boolean editing;


    @Override
    public void beforeTextChanged(CharSequence charSequence, int start, int before, int count) {

    }

    @Override
    public void onTextChanged(CharSequence text, int start, int before, int count) {
        if (text.toString().equals(updatedText) || editing) return;

        String digitsOnly = text.toString().replaceAll("\\D", "");
        int digitLen = digitsOnly.length();

        if (digitLen < MIN_FORMAT_LENGTH || digitLen > MAX_FORMAT_LENGTH) {
            updatedText = digitsOnly;
            return;
        }

        if (digitLen <= 4) {
            String month = digitsOnly.substring(0, 2);
            String day = digitsOnly.substring(2);

            updatedText = String.format(Locale.US, "%s/%s", month, day);
        }
        else {
            String month = digitsOnly.substring(0, 2);
            String day = digitsOnly.substring(2, 4);
            String year = digitsOnly.substring(4);

            updatedText = String.format(Locale.US, "%s/%s/%s", month, day, year);
        }
    }

    @Override
    public void afterTextChanged(Editable editable) {

        if (editing) return;

        editing = true;

        editable.clear();
        editable.insert(0, updatedText);

        editing = false;
    }
}

回答5:

Try using a library that solves this problem since masking it's not available out of the box. There are a lot of corner cases (like adding/deleting characters in the middle of already masked text) and to properly handle this you'll end up with a lot of code (and bugs).

Here are some available libraries:
https://github.com/egslava/edittext-mask
https://github.com/dimitar-zabaznoski/MaskedEditText
https://github.com/pinball83/Masked-Edittext
https://github.com/RedMadRobot/input-mask-android
https://github.com/santalu/mask-edittext

** Mind that at the time of writing these libraries are not without issues, so it's your responsibility to choose which one fits you best and test the code.