onTouchEvent() in Android programming. Android Game development : I am developing a game application using android.

> The Object(a box) slides up and down. And it has to hit the
> objects(orange and pink balls) coming towards it from the right end of
> the screen that would increase his score.
> 
> There will be black balls as well(shot from the right end of the
> screen) which he should avoid hitting.

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[enter image description here][1]

I am having problem with 

    onTouchEvent(MotionEvent me)
function while implementing the code.

I am following [this][2] tutorial in [this series of tutorials][3].

________________________________

 My Questions:

1)To use the `onTouchEvent(MotionEvent me)`  function do I need to import any class?

2)The tutorial has declared the`onTouchEvent(MotionEvent me)` outside the `onCreate` method. Which is okay. But the program has not called it anywhere. How does it work then?

3)After writing the code as mentioned in the tutorial, the program is not working as intended. The box appears when the activity starts. However, it disappears as soon as I click on the screen. What could be the problem?

> ActivityMain.XML

    <?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">
    
        <TextView
            android:id="@+id/scoreLabel"
            android:layout_width="match_parent"
            android:layout_height="50dp"
            android:text=" : 300"
            android:paddingLeft="10dp"
            android:gravity="center_vertical"  />
    
        <FrameLayout
            android:id="@+id/frame"
            android:layout_width="match_parent"
            android:layout_height="match_parent">
    
            <TextView
                android:id="@+id/startLabel"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:textSize="30sp"
                android:layout_gravity="center_horizontal"
                android:layout_marginTop="130dp"/>
    
            <ImageView
    
                android:id="@+id/box"
                android:layout_width="50dp"
                android:layout_height="50dp"
                android:src="@drawable/box"
                android:layout_gravity="center_vertical" />
    
            <ImageView
                android:id="@+id/orange"
                android:layout_width="20dp"
                android:layout_height="20dp"
                android:src="@drawable/orange" />
    
            <ImageView
                android:id="@+id/black"
                android:layout_width="24dp"
                android:layout_height="24dp"
                android:src="@drawable/black" />
    
            <ImageView
                android:id="@+id/pink"
                android:layout_width="16dp"
                android:layout_height="16dp"
                android:src="@drawable/pink" />
    
    
    
        </FrameLayout>
    
    </RelativeLayout>


> MainActivity.java




    package com.example.catcheggs1;
    
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.view.MotionEvent;
    import android.view.View;
    import android.widget.ImageView;
    import android.widget.TextView;
    
    public class MainActivity extends AppCompatActivity {
    
        private TextView scoreLabel;
        private TextView startLabel;
        private ImageView box;
        private ImageView orange;
        private ImageView black;
        private ImageView pink;
    
        //Position
        private int boxY;
    
    
    
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
    
            scoreLabel=(TextView)findViewById(R.id.scoreLabel);
            startLabel=(TextView)findViewById(R.id.startLabel);
            box=(ImageView)findViewById(R.id.box);
            orange=(ImageView)findViewById(R.id.orange);
            pink=(ImageView)findViewById(R.id.pink);
            black=(ImageView)findViewById(R.id.black);
    
            //Move To Out of Screen
            orange.setX(-80);
            orange.setY(-80);
            pink.setX(-80);
            pink.setY(-80);
            black.setX(-80);
            black.setY(-80);
    
    
            //Temporary
            startLabel.setVisibility(View.INVISIBLE);
            boxY=500;
    
    
        }
    
        public boolean onTouchEvent(MotionEvent me)
        {
           if(me.getAction()==MotionEvent.ACTION_DOWN)
           {
               boxY -= 1 ;
           }
           box.setY(boxY);
    
           return true;
        }
    }




  [1]: https://i.stack.imgur.com/TumVg.png
  [2]: https://www.youtube.com/watch?v=hRXIgokEk-Y&list=PLRdMAPi4QUfbIg6dRXf56cbMfeYtTdNSA&index=3
  [3]: https://www.youtube.com/watch?v=ojD6ZDi2ep8&list=PLRdMAPi4QUfbIg6dRXf56cbMfeYtTdNSA