Android EditText - Delete the last letter with a b

问题:

I have to buttons that writes A and B to an edittext. If there is something in the edittext how can I delete the last letters with the "Del" button? My layout:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >

<Button
    android:id="@+id/buttonb"
    android:layout_width="100dp"
    android:layout_height="100dp"
    android:layout_alignParentLeft="true"
    android:layout_below="@+id/buttona"
    android:text="@string/buttonb"
    android:textSize="50sp"
    android:textStyle="bold" />

<Button
    android:id="@+id/buttona"
    android:layout_width="100dp"
    android:layout_height="100dp"
    android:layout_alignParentLeft="true"
    android:layout_centerVertical="true"
    android:text="@string/buttona"
    android:textSize="50sp"
    android:textStyle="bold" />

<Button
    android:id="@+id/buttondel"
    android:layout_width="100dp"
    android:layout_height="100dp"
    android:layout_alignParentRight="true"
    android:layout_centerVertical="true"
    android:text="@string/buttondel"
    android:textSize="50sp"
    android:textStyle="bold" />

<EditText
    android:id="@+id/editText"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_alignParentTop="true"
    android:ems="58"
    android:textSize="20sp"
    android:textStyle="bold"
    android:inputType="text" >

    <requestFocus />
</EditText>

</RelativeLayout>

And my java:

package com.koostamas.keyboard;

import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.app.Activity;

public class MainActivity extends Activity implements OnClickListener {

Button buttona, buttonb;
EditText editText;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
editText = (EditText) findViewById(R.id.editText);

addListenerOnButton();
}


   public void addListenerOnButton() {

buttona = (Button) findViewById(R.id.buttona);
buttona.setOnClickListener(this);
buttona.getText();
buttonb = (Button) findViewById(R.id.buttonb);
buttonb.setOnClickListener(this);
buttonb.getText();

   }

public void onClick(View v) {

    Button buttona = (Button)v;
    editText.setText(editText.getText().toString()+buttona.getText().toString());


}

public void onClick1(View v) {

    Button buttonb = (Button)v;
    editText.setText(editText.getText().toString()+buttonb.getText().toString());


}
}

So I want to make it. Please help me! Thanks in advance.

回答1:

Yes you can create an onClickListener and just get the text from edit text and delete the last character.

Button delete = (Button) findViewById(R.id.buttondel);
if( delete != null ) {
   delete.setOnClickListener(new OnClickListener() {
      @Override
      public void onClick() {
         String textString = editText.getText().toString();
         if( textString.length() > 0 ) {
            editText.setText(textString.substring(0, textString.length() - 1 ));
            editText.setSelection(editText.getText().length());//position cursor at the end of the line
         }
      }
   });
}

Edit: Also don't forget to check the string length is greater than 0 before doing this in the event a or b hasn't been pressed when the user hits delete.

回答2:

Setting new text#1

CharSequence text = edittext.getText();
edittext.setText(text.subSequence(0, text.length() - 1));

Setting new text#2

CharSequence text = v.getText();
edittext.setText("");
edittext.append(text, 0, text.length() - 1);

Deleting editable

int length = editText.getText().length();
if (length > 0) {
    editText.getText().delete(length - 1, length);
}

Subsequencing editable

int length = editText.getText().length();
if (length > 0) {
    editText.getText().subSequence(0, length - 1);
}

Deleting by dispatching delete key event.

edittext.dispatchKeyEvent(new KeyEvent(KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_DEL));

回答3:

String text = editText.getText().toString();
if(text.length() > 0){
  text = str.substring(0, str.length()-1);
   editText.setText(text);
}

回答4:

one limitation of others answer is if cursor not in last position then also it delete the last character that limitation is removed in this answer Write down at your on click of button

int end = ((EditText)findViewById(R.id.one)).getSelectionEnd();
 if(end>0){
           SpannableStringBuilder selectedStr = new SpannableStringBuilder(((EditText) findViewById(R.id.one)).getText());
           selectedStr.replace(end - 1, end, "");
           ((EditText) findViewById(R.id.one)).setText(selectedStr);
           ((EditText) findViewById(R.id.one)).setSelection(end-1);
        }