Button Listeners

1. Anonymous Inner Class

public class MainActivity extends AppCompatActivity {
    buttonStart.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            // DO SOMETHING
        }
    });
}

2. Lambda expressions

public class MainActivity extends AppCompatActivity {
    buttonStart.setOnClickListener(view -> {
    // DO SOMETHING
    });
}

3. Method Reference

public class MainActivity extends AppCompatActivity {
    buttonStart.setOnClickListener(this::onClick);
}

private void onClick(View v) {
    int id = v.getId();
    // DO SOMETHING
}

4. Interface Object

public class MainActivity extends AppCompatActivity {
    buttonStart.setOnClickListener(onClickListener);
}

View.OnClickListener onClickListener = new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        int id = v.getId();
        // DO SOMETHING
    }
};

5. Interface Object (Lambda)

public class MainActivity extends AppCompatActivity {
    buttonStart.setOnClickListener(onClickListener);
}

View.OnClickListener onClickListener = v -> {
    int id = v.getId();
    // DO SOMETHING
};

6. Interface in Activity

Implements View.OnClickListener interface.

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    buttonStart.setOnClickListener(this);
}

@Override
public void onClick(View v) {
    int id = v.getId();
    // DO SOMETHING
}

Last modified: 05 February 2026