android 监听器

activity_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
>

<Button
android:id="@+id/bt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button"
android:onClick="click"/>

</LinearLayout>

1.方法一   匿名内部类

public class MainActivity extends Activity {

protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button bt = (Button)findViewById(R.id.bt);
bt.setOnClickListener(
new OnClickListener(){//匿名内部类对象

@Override
public void onClick(View v) {
Toast.makeText(MainActivity.this, "click Button", Toast.LENGTH_SHORT).show();//注意this MainActivity.this
}});
}

}

方法二 实现OnClickListener接口
public class MainActivity extends Activity implements OnClickListener{

protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button bt = (Button)findViewById(R.id.bt);
bt.setOnClickListener(this);//将this当成对象传过去
}

@Override
public void onClick(View v) {
Toast.makeText(MainActivity.this, "click Button", Toast.LENGTH_SHORT).show();
}
}

方法三 新建一个接口对象
public class MainActivity extends Activity {

protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button bt = (Button)findViewById(R.id.bt);
OnClickListener mylistener = new myOnClickListener();//新建一个接口对象
bt.setOnClickListener(mylistener);
}

class myOnClickListener implements OnClickListener{

@Override
public void onClick(View v) {
Toast.makeText(MainActivity.this, "click Button", Toast.LENGTH_SHORT).show();
}

}

}

方法四  在xml文件中写onclick方法
public class MainActivity extends Activity {
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}

public void click(View v){
Toast.makeText(MainActivity.this, "click Button", Toast.LENGTH_SHORT).show();
}
}