Android开发之onClick事件的三种写法

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>