The fillOval fits an oval inside a rectangle, with width=r, height = r you get a circle. If you want fillOval(x,y,r,r) to draw a circle with the center at (x,y) you will have to displace the rectangle by half its width and half its height. This will draw a circle with center at x,y
The pack method sizes the frame so that all its contents are at or above their preferred sizes. An alternative to pack is to establish a frame size explicitly by calling setSize or setBounds (which also sets the frame location). In general, using pack is preferable to calling setSize, since pack leaves the frame layout manager in charge of the frame size, … Read more
addNotify() gets called whenever the Component gets added to a Container. This method can therefore be used to gain parent information without the risk of having a null parent, which in the constructor is more than likely. requestFocus() makes a request that the given Component gets set to a focused state. This method requires that … Read more
OK what I am trying to do here is create a game where the object/ball is controlled by clicking on the object with the mouse, pulling back the mouse (the distance the mouse is pulled back will determine the velocity of the object) and on releasing the button the object will move (it’s angle of … Read more
JPanel doesn’t have ActionListener capabilities. Instead, you need to use a MouseListener Take a look at How to Write Mouse Listeners for more details…
Try calling somePanel.revalidate(). That will tell the AWT that you have changed the component tree. EDIT: Changed from invalidate to revalidate
Here’s how I do it (with a little more info on how to load an image):
Usage depends on whether the component’s parent has a layout manager or not. setSize() — use when a parent layout manager does not exist; setPreferredSize() (also its related setMinimumSize and setMaximumSize) — use when a parent layout manager exists. The setSize() method probably won’t do anything if the component’s parent is using a layout manager; the places this will typically have an … Read more
You may use Graphics.drawPolygon(int[], int[], int) where the first int[] is the set of x values, the second int[] is the set of y values, and the int is the length of the array. (In a triangle’s case, the int is going to be 3) Example: Output: