package a.a;  

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

public class AActivity extends Activity {  
    /** Called when the activity is first created. */  

    EditText Ev1;  

    @Override  
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.main);  

        Ev1 = (EditText)findViewById(R.id.editText1);    

        //第一种方式    
        Button Btn1 = (Button)findViewById(R.id.button1);//获取按钮资源    
        Btn1.setOnClickListener(new Button.OnClickListener(){//创建监听    
            public void onClick(View v) {    
                String strTmp = "点击Button01";    
                Ev1.setText(strTmp);    
            }    

        });    

        //第二种方式    
        Button Btn2 = (Button) findViewById(R.id.button2);//获取按钮资源    
        Btn2.setOnClickListener(listener);//设置监听    

    }  

    Button.OnClickListener listener = new Button.OnClickListener(){//创建监听对象    
        public void onClick(View v){    
            String strTmp="点击Button02";    
            Ev1.setText(strTmp);    
        }    

    };  


    //第三种方式(Android1.6版本及以后的版本中提供了)    
    public void Btn3OnClick(View view){    
        String strTmp="点击Button03";  
        Ev1.setText(strTmp);  

    }    
}  

布局文件

<?xml version="1.0" encoding="utf-8"?>  
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:layout_width="fill_parent"  
    android:layout_height="fill_parent"  
    android:orientation="vertical" >  

    <TextView  
        android:layout_width="fill_parent"  
        android:layout_height="wrap_content"  
        android:text="@string/hello" />  

    <Button  
        android:id="@+id/button1"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:text="Button1" />  

    <Button  
        android:id="@+id/button2"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:text="Button2" />  

 <Button  
        android:id="@+id/button3"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:text="Button3"   
        android:onClick="Btn3OnClick"/>  

 <EditText  
     android:id="@+id/editText1"  
     android:layout_width="match_parent"  
     android:layout_height="wrap_content" >  

     <requestFocus />  
 </EditText>  

</LinearLayout>