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);  

    }

}  

<?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>