How to use more than one extends?

When I create the project it comes like this

public class MainActivity extends AppCompatActivity{

Would you like to use more than extends how to do?

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.ScaleGestureDetector.SimpleOnScaleGestureListener;
import android.view.View;
import android.widget.ImageView;


public class MainActivity extends AppCompatActivity implements SimpleOnScaleGestureListener {
private ImageView imageView;
private float scale = 1f;

@Override
public boolean onScale(ScaleGestureDetector detector) {

    //Factor de zoom correspondente ao movimento feito
    float scaleFactor = detector.getScaleFactor();

    //Executa o zoom
    performZoom(scaleFactor);
    return true;
}


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    scaleGestureDetector = new ScaleGestureDetector(this,new MainActivity());
    view.setOnTouchListener(new View.OnTouchListener() {

        @Override
        public boolean onTouch(View v, MotionEvent event) {

            v.performClick();
            //Chamar o onTouchEvent do nosso ScaleGestureDetector
            scaleGestureDetector.onTouchEvent(event);
            return true;
        }
    });
     }



private void performZoom(float scaleFactor) {
    scale *= scaleFactor;
    scale = Math.max(0.1f, Math.min(scale, 5.0f));
    imageView.setScaleX(scale);
    imageView.setScaleY(scale);
}

}