Android监听EditText内容变化

1、给EditText追加ChangedListener

EditText editText = (EditText) findViewById(R.id.edittext);



editText.addTextChangedListener(watcher); 

 

2、描述监听

 

private TextWatcher watcher = new TextWatcher() {



@Override

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

// TODO Auto-generated method stub



}



@Override

public void beforeTextChanged(CharSequence s, int start, int count,

int after) {

// TODO Auto-generated method stub



}



@Override

public void afterTextChanged(Editable s) {

// TODO Auto-generated method stub



}

};

 

 

 

监听EditText的变化

使用EditText的addTextChangedListener(TextWatcher watcher)方法对EditText实现监听，TextWatcher是一个接口类，所以必须实现TextWatcher里的抽象方法：

 

当EditText里面的内容有变化的时候，触发TextChangedListener事件，就会调用TextWatcher里面的抽象方法。

MainActivity.java

package com.lingdududu.watcher;



import android.app.Activity; 

import android.app.AlertDialog; 

import android.content.DialogInterface; 

import android.os.Bundle; 

import android.text.Editable; 

import android.text.TextWatcher; 

import android.util.Log; 

import android.widget.EditText; 



publicclass MainActivity extends Activity { 

private EditText text; 

String str; 

@Override

publicvoid onCreate(Bundle savedInstanceState) { 

super.onCreate(savedInstanceState); 

setContentView(R.layout.main); 



text = (EditText)findViewById(R.id.text); 

text.addTextChangedListener(textWatcher); 

} 



private TextWatcher textWatcher = new TextWatcher() { 



@Override

publicvoid afterTextChanged(Editable s) { 

// TODO Auto-generated method stub 

Log.d("TAG","afterTextChanged--------------->"); 

} 



@Override

publicvoid beforeTextChanged(CharSequence s, int start, int count, 

int after) { 

// TODO Auto-generated method stub 

Log.d("TAG","beforeTextChanged--------------->"); 

} 



@Override

publicvoid onTextChanged(CharSequence s, int start, int before, 

int count) { 

Log.d("TAG","onTextChanged--------------->"); 

str = text.getText().toString(); 

try { 

//if ((heighText.getText().toString())!=null) 

Integer.parseInt(str); 



} catch (Exception e) { 

// TODO: handle exception 

showDialog(); 

} 



} 

}; 

privatevoid showDialog(){ 

AlertDialog dialog; 

AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this); 

builder.setTitle("消息").setIcon(android.R.drawable.stat_notify_error); 

builder.setMessage("你输出的整型数字有误，请改正"); 



builder.setPositiveButton("确定",new DialogInterface.OnClickListener(){ 

@Override

publicvoid onClick(DialogInterface dialog, int which) { 

// TODO Auto-generated method stub 



} 

}); 

dialog = builder.create(); 

dialog.show(); 

} 

} 

 

main.xml

<?xmlversion="1.0"encoding="utf-8"?>

<LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android"

android:orientation="vertical"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

>

<TextView

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="请输入整型数字"

/>

<EditText

android:id="@+id/text"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

/>

</LinearLayout>

 

效果图：

当我们在输入框输入不是整型数字的时候，会立刻弹出输入框，提示你改正