CODEWITHSUNDEEP
android
user2391890
user2391890

Reputation: 649

Why I get Null Pointer Exception in Android

I am facing issue of NullPointerException. In my app I have two classes MainActivity and Test. I am creating object main of MainActivity inside Test class. When I call display method of MainActivity inside Test class main.display(); I get the NullPointerException. Please check my sample code below and recommend me changes where I am doing wrong. 

public class MainActivity extends Activity {


    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT); // Fixed
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON); // orientation

        setContentView(R.layout.training_ten_position);

        Test test = new Test(10);

    }


    public  MainActivity()  {
        super();
    }
    public void display() {

    }


    }



public class Test {
        .
        .
        .
        MainActivity main;

        public Test(int duration) {
            // Initializing data member
            main = new MainActivity();
        }

        public void delay() {
            .
            .
            .
            main.display();
        }

Upvotes: 0

Views: 97

Answers (1)

Biraj Zalavadia
Biraj Zalavadia

Reputation: 28484

Do like this

do nor create instance of MainActivity class.

public class MainActivity extends Activity{

 //Make Your Function static 

  public static void display(){
    //Do your code 
    // whatever variables or views you want to use in this method make them static
  }

}

public class Test extend Activity{
   //how call display function
   MainActivity.display();

}

Upvotes: 1

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