View::setTag()跟getTag()

View中的setTag（Onbect）表示给View添加一个格外的数据，以后可以用getTag()将这个数据取出来。

可以用在多个Button添加一个监听器，每个Button都设置不同的setTag。这个监听器就通过getTag来分辨是哪个Button 被按下。

    
    
import android.app.Activity;     
import android.os.Bundle;     
import android.view.View;     
import android.widget.Button;     
    
public class Main extends Activity {     
        
    @Override    
    public void onCreate(Bundle savedInstanceState) {     
        super.onCreate(savedInstanceState);     
        setContentView(R.layout.main);     
        Button button1 = (Button) findViewById(R.id.Button01);     
        Button button2 = (Button) findViewById(R.id.Button02);     
        Button button3 = (Button) findViewById(R.id.Button03);     
        Button button4 = (Button) findViewById(R.id.Button04);     
        MyListener listener = new MyListener();     
        button1.setTag(1);     
        button1.setOnClickListener(listener);     
        button2.setTag(2);     
        button2.setOnClickListener(listener);     
        button3.setTag(3);     
        button3.setOnClickListener(listener);     
        button4.setTag(4);     
        button4.setOnClickListener(listener);     
    }     
    
    public class MyListener implements View.OnClickListener {     
    
        @Override    
        public void onClick(View v) {     
            int tag = (Integer) v.getTag();     
            switch (tag) {     
            case 1:     
                System.out.println("button1 click");     
                break;     
            case 2:     
                System.out.println("button2 click");     
                break;     
            case 3:     
                System.out.println("button3 click");     
                break;     
            case 4:     
                System.out.println("button4 click");     
                break;     
            }     
        }     
    
    }     
    
}