Android 按键三种监测方式

package com.example.butclicktest;

import android.os.Bundle; import android.app.Activity; import android.view.Menu; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.Toast;

public class MainActivity extends Activity implements OnClickListener {

 private Button btn_1,btn_2,btn_3;  @Override  protected void onCreate(Bundle savedInstanceState) {   super.onCreate(savedInstanceState);   setContentView(R.layout.activity_main);  btn_1=(Button)findViewById(R.id.button1);  btn_1.setOnClickListener(new OnClickListener() {      @Override   public void onClick(View v) {    // TODO Auto-generated method stub    Toast.makeText(MainActivity.this, "第一个", Toast.LENGTH_SHORT).show();   }  });    OnClickListener list=new OnClickListener()  {   @Override   public void onClick(View v) {    // TODO Auto-generated method stub    Toast.makeText(MainActivity.this, "第二个", Toast.LENGTH_SHORT).show();   }  };  btn_2=(Button)findViewById(R.id.button2);  btn_2.setOnClickListener(list);  btn_3=(Button)findViewById(R.id.button3);  btn_3.setOnClickListener(this);  }

 @Override  public boolean onCreateOptionsMenu(Menu menu) {   // Inflate the menu; this adds items to the action bar if it is present.   getMenuInflater().inflate(R.menu.main, menu);   return true;  }

 @Override  public void onClick(View v) {   // TODO Auto-generated method stub   Toast.makeText(MainActivity.this, "第三个", Toast.LENGTH_SHORT).show();  }

}