Setting the window shape in Java (shaped JFrame)

Question

I'm trying to set the shape of my JFrame window to an ellipse, but instead it is throwing the following error:

java.lang.IllegalArgumentException: wrong number of arguments
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at Splash.setShape(Splash.java:48)
    at Splash.<init>(Splash.java:25)
    at BackOffice.init(BackOffice.java:40)
    at sun.applet.AppletPanel.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)

The problem is that I am sending 2 parameters and the method only accepts 2 parameters so I can't see where I am getting this error from? The line that the error points to is the line which says mSetWindowShape.invoke(this, shape); here is the relevant method:

private void setShape() {
    Class<?> awtUtilitiesClass;
    try {
        awtUtilitiesClass = Class.forName("com.sun.awt.AWTUtilities");
        Method mSetWindowShape = awtUtilitiesClass.getMethod("setWindowShape", Window.class, Shape.class);
        Shape shape = (Shape) new Ellipse2D.Double(0, 0, getWidth(), getHeight());
        mSetWindowShape.invoke(this, shape);
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    } catch (IllegalArgumentException e) {
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    } catch (InvocationTargetException e) {
        e.printStackTrace();
    } catch (SecurityException e) {
        e.printStackTrace();
    } catch (NoSuchMethodException e) {
        e.printStackTrace();
    }

}

EDIT: I took off one paramter and got the same error (wrong number of arguments). I then put in 3 parameters (window, shape, 0) and got 'argument type mismatch'. I then tried a boolean and a string as the third parameter but those gave the 'argument type mismatch' too. I don't understand this because in the tutorial it only shows 2 parameters. Now apparently there are three?

Answer 1

Your:

mSetWindowShape.invoke(this, shape);

should be:

mSetWindowShape.invoke(null, this, shape);

The Method.invoke() method takes the object the method is being invoked on as the first argument. Since AWTUtilities.setWindowShape() is a static method, the first argument should be null.

Also, if you can target Java 7, use Frame.setShape() instead as it is now officially part of the API. It is possible for com.sun.* classes to go away in the future.

Answer 2

I hope, this is the right method your code be calling for frameObject.setShape(shape); Hope that helps. Regards.