（二）AS给button添加点击事件

三种方法给Button添加点击事件

（一）通过button的id，添加继承View.OnClickListener的监听实现

    <Buttonandroid:id="@+id/btn_button2"android:text="按钮2"android:layout_width="match_parent"android:layout_height="wrap_content" />

public class MainActivity extends AppCompatActivity implements View.OnClickListener {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);findViewById(R.id.btn_button2).setOnClickListener(this);}
@Overridepublic void onClick(View v) {if(v.getId()==R.id.btn_button2){Toast.makeText(getApplicationContext(),"Button 2 clicked",Toast.LENGTH_LONG).show();}}
}

（二）通过Text直接绑定点击事件

    <Buttonandroid:onClick="button1OnClick"android:layout_width="match_parent"android:text="按钮1"android:layout_height="wrap_content" />

public class MainActivity extends AppCompatActivity implements View.OnClickListener {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);
}public void button1OnClick(View view) {Toast.makeText(getApplicationContext(),"Button 1 clicked",Toast.LENGTH_LONG).show();}

}

（二）在setOnClickListener中直接添加方法

    <Buttonandroid:id="@+id/btn_button3"android:text="按钮3"android:layout_width="match_parent"android:layout_height="wrap_content" />

public class MainActivity extends AppCompatActivity implements View.OnClickListener {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);
findViewById(R.id.btn_button3).setOnClickListener(new View.OnClickListener(){@Overridepublic void onClick(View v) {Toast.makeText(getApplicationContext(),"Button 3 clicked",Toast.LENGTH_LONG).show();}});}

}