CODEWITHSUNDEEP
javaandroidnullpointerexception
Emanuel Graf
Emanuel Graf

Reputation: 766

measuring the time is not working

I want to measure the time between the 1st button click and the 3rd button click. I'm not getting any sort of thext on the main screen, where the textView1 is placed. If i'm launching the app, I'm getting a nullpointer. What does thar mean?

@Override

public void onClick(View v) {
    Random r = new Random();
    int x = r.nextInt(800);
      int y = r.nextInt(800);
      long startTime =  SystemClock.elapsedRealtime();
      i++;

    View b = findViewById(R.id.start_time);
    b.setX(x);  
    b.setY(y);
    if (i == 1 ) {

        b.setX(+9);  
        b.setY(+5);
    }
    if (i == 2 ) {
        b.setX(x);  
        b.setY(y);
    }
    if (i == 3 ) {
        b.setX(x);  
        b.setY(y);
    }
    else if (i == 4) {
        long difference = SystemClock.elapsedRealtime()  - startTime;

          Intent intent = new Intent(Game.this, MainScreen.class);
          intent.putExtra("time",difference);
         // Toast.makeText(getApplicationContext(), getIntent().getStringExtra("time"), Toast.LENGTH_LONG).show();
          textview1.setText(getIntent().getStringExtra("time"));
        finish();
    }


}

Upvotes: 0

Views: 46

Answers (1)

Gabe Sechan
Gabe Sechan

Reputation: 93561

Well, that function isn't doing what you think. startTime is a local variable and will be cleared every time the function exits. If you want to keep the time between button presses, you need to use a class variable. You would also not want to initialize startTime unless i==1. Right now you're doing it each time and that will cause it to always have a 0 (or very close to 0) difference.

Also why are you using an intent for the toast? At best that's a waste, at worst its a problem. There's no reason for it. Just convert the difference to a string.

Upvotes: 1

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