<Button
    android:id="@+id/bt1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:onClick="doClick"
    android:text="XML添加doClick"
    android:layout_above="@+id/bt2"
    android:layout_marginBottom="47dp"
    />

public void doClick(View view) {
    switch (view.getId()) {
      case R.id.bt1:
        Toast.makeText(MainActivity.this, "第一种点击事件：Xml添加doClick", Toast.LENGTH_SHORT).show();
        break;

    }

  }

Button bt2 = (Button) findViewById(R.id.bt2);
    bt2.setOnClickListener(new View.OnClickListener() {
       @Override
       public void onClick(View v) {
         Toast.makeText(MainActivity.this, "第二种点击事件：匿名内部类", Toast.LENGTH_SHORT).show();
       }
     });

Button bt3 = (Button) findViewById(R.id.bt3);
     bt3.setOnClickListener(new MyListener());
class MyListener implements View.OnClickListener {
  @Override
  public void onClick(View v) {
    Toast.makeText(MainActivity.this, "第三种方法：自定义点击事件", Toast.LENGTH_SHORT).show();
  }
}

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
 Button bt4=(Button)findViewById(R.id.bt4);
  bt4.setOnClickListener(this);
}

@Override
  public void onClick(View v) {
    switch (v.getId()) {
      case R.id.bt4:
        Toast.makeText(MainActivity.this,
            "第四种点击事件：Activity继承View.OnClickListener，由Activity实现OnClick(View view)方法",
            Toast.LENGTH_SHORT).show();
    }
  }
}