How can I display an integer that counted the time from my game in my endscreen?

Question

I'm making a simple game to learn how to use Android Studio. The objective of the game is to do some simple tasks as fast as possible. In my main game screen, I have a thread that makes an int count up every second, so the player knows how much time has gone by. When the player has done all the simple tasks, the game goes to the end screen. Now I want to display the time in the endscreen, so the player knows how fast they finished. I get an error when I run the game.

This is the code to run the thread every second:

Timer d = new Timer(true);
thread1 thread1 = new thread1(this, myCanvas);
t.scheduleAtFixedRate(thread1, 0, 1000); 

This is the tick function that the thread does every second:

public void tick1(){
    timer++;
}

This is the getter for the timer:

public int getTimer(){
    return timer;
}

When the game ends and it goes to the endscreen, I use the getTimer() to have a textview that should display the timer:

err = (TextView)findViewById(R.id.textView);
err.setText("Tijd: "+ timer+"");

This is the error message I get when I try to run it:

2021-03-06 11:18:38.153 21729-21729/com.example.test_game E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.test_game, PID: 21729
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.test_game/com.example.test_game.Eindscherm}: java.lang.NullPointerException: Attempt to invoke virtual method 'int com.example.test_game.MyCanvas.getTimer()' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3792)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3968)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2307)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:246)
        at android.app.ActivityThread.main(ActivityThread.java:8506)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:602)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1130)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int com.example.test_game.MyCanvas.getTimer()' on a null object reference
        at com.example.test_game.Eindscherm.onCreate(Eindscherm.java:24)
        at android.app.Activity.performCreate(Activity.java:8198)
        at android.app.Activity.performCreate(Activity.java:8182)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3765)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3968) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2307) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:246) 
        at android.app.ActivityThread.main(ActivityThread.java:8506) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:602) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1130) 

error

Answer 1

I think when you are in end activity your are calling getTimer() method that this method is in another activity.

so you can not do that in activities. because activities are different with JAVA classes.

all you need to do is passing the data to end activity. don't worry it is so simple and i will show you how to do that.

in first activity:

FirstAcitivity {

    // when you want to go to SecondActivity

    Intent i = new Intent(context, SecondActivity.class)
    //passing the data by Intent
    i.putExtra("ex1", yourIntegenr);
}

in second activity:

SecondActivity{
   
    //checking the Intent has valid data
    if (getIntent().getExtras() != null) {
    
        //getting the data from Intent
        int time = getIntent().getExtras().getSerializable("ex1");
        yourTextView.setText(time.toString());
    }
}