Android 按钮点击事件

public class MainActivity extends AppCompatActivity {

    private Button button;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        initView();
    }

    private void initView() {
        button = (Button) findViewById(R.id.btn);
        
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(MainActivity.this, "匿名内部类 监听", Toast.LENGTH_SHORT).show();
            }
        });
    }
}

public class MainActivity extends AppCompatActivity {

    private Button button;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        initView();
    }
    
    private void initView() {
        button = (Button) findViewById(R.id.btn);

        button.setOnClickListener(new MyClickListener());
    }

    class MyClickListener implements View.OnClickListener {

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

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private Button button;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        initView();
    }

    private void initView() {
        button = (Button) findViewById(R.id.btn);

        button.setOnClickListener(this);
    }
    
    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.btn:
                Toast.makeText(MainActivity.this, "Activity 实现 View.OnClickListener 接口", Toast.LENGTH_SHORT).show();
                break;
            default:
                break;
        }
    }
}

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

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void xmlOnClick(View view) {
        switch (view.getId()) {
            case R.id.btn:
                Toast.makeText(MainActivity.this, "在 xml 文件中使用 onClick 属性", Toast.LENGTH_SHORT).show();
                break;
            default:
                break;
        }
    }
}