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, buttondel;
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);
buttondel = (Button) findViewById(R.id.buttonb);
buttondel.setOnClickListener(this);
}
public void onClick(View v) {
switch(v.getId()) {
case R.id.buttona :
Button buttona = (Button)v;
editText.setText(editText.getText().toString()+buttona.getText().toString());
break;
case R.id.buttondel :
String text = editText.getText().toString();
editText.setText(text.substring(0, text.length() - 1));
break;
}
}
}
How can I do it? Thanks inn advance.
回答1:
You can retrieve the text of EditText and then get the sub-string of that text and set again that text to EditText as below...
String text = editText.getText().toString();
editText.setText(text.substring(0, text.length() - 1));
You can also use following procedure....it will be more efficient.
int length = editText.getText().length();
if (length > 0) {
editText.getText().delete(length - 1, length);
}
You should use switch-case as below...and handle your nuttondel onclick() as follows...
public class MainActivity extends Activity implements OnClickListener {
Button buttona, buttonb;
Button buttonDel;
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);
buttonb = (Button) findViewById(R.id.buttonb);
buttonb.setOnClickListener(this);
buttonDel = (Button) findViewById(R.id.buttondel);
buttonDel.setOnClickListener(this);
}
public void onClick(View v) {
switch(v.getId()) {
case R.id.buttona:
editText.setText(editText.getText().toString()+buttona.getText().toString());
break;
case R.id.buttonb:
editText.setText(editText.getText().toString()+buttonb.getText().toString());
break;
case R.id.buttondel:
int length = editText.getText().length();
if (length > 0) {
editText.getText().delete(length - 1, length);
}
break;
}
}
}
回答2:
Using substring() method , you can do it,
String str = myEditText.getText().toString();
str = str.substring ( 0, str.length() - 1 );
// Now set this Text to your edit text
myEditText.setText ( str );
you need to write above lines in onClick() method.
回答3:
str=edittext.gettext+"";
str.length();
then for loop
or str1 = str.substring ( 0, str.length() - 1 );
来源：https://stackoverflow.com/questions/22316563/how-to-delete-the-last-letter-from-edittext-with-button