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>