CODEWITHSUNDEEP
javaexception
Alexandre Toqué
Alexandre Toqué

Reputation: 193

Toolkit class in java

I am trying to create custom cursors for JButtons in Java. So I use the Toolkit class. However Toolkit methods somehow fail to load my image. Here is my code:

public class ButtonPerso extends JButton{

 private Toolkit toolkit; 

 private Cursor myCursor; 

 private Point hotSpot;

 private Image image;

 public ButtonPerso(String label) {

  super(label);

  Toolkit.getDefaultToolkit();

  image = toolkit.createImage("candle.gif" );

  hotSpot = new Point(0, 0);  

  //myCursor = toolkit.createCustomCursor(image, hotSpot, "Candle");
  myCursor = toolkit.createCustomCursor(image, hotSpot, "Candle");

  addMouseListener(new MouseAdapter() {
    public void mouseEntered(MouseEvent e) {
      //setCursor (Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
      setCursor(myCursor);
    }
      }
  );

 }
}

Everytime I get this error:

 Exception in thread "main" java.lang.NullPointerException
    at GUI.ButtonPerso.<init>(ButtonPerso.java:36)
    at GUI.Menu.<init>(Menu.java:61)
    at GUI.Fenetre.<init>(Fenetre.java:18)
    at Main.main(Main.java:34)

So I guess there is something happening with these exception: IndexOutOfBoundsException,HeadlessException. I tried to locate the problem:

try {
  myCursor = toolkit.createCustomCursor(Menu.image, hotSpot, "Candle");
  }
  catch (HeadlessException h) {

  }

  catch (IndexOutOfBoundsException i) {
    System.out.println("index except");
  }

But I still get the same warnings, I don't know what to do can you give me a hand ? Perhaps it comes from my image

Upvotes: 0

Views: 225

Answers (2)

Jesper
Jesper

Reputation: 206926

Instead of this line:

Toolkit.getDefaultToolkit();

You'll want to write:

toolkit = Toolkit.getDefaultToolkit();

Otherwise toolkit will remain null, and you'll get a NullPointerException when you try to call a method on it.

Upvotes: 3

AllTooSir
AllTooSir

Reputation: 49412

private Toolkit toolkit; 
\\ toolkit is not initialized and hence it is a null reference.
\\ Below line will throw NullPointerException
image = toolkit.createImage("candle.gif" );

\\ You need to assign the toolkit first.
toolkit = Toolkit.getDefaultToolkit();

Upvotes: 1

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