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How to stop graphics from disappearing?

Kristo Liiva

Joined: Oct 30, 2009
Posts: 4
I have a JPanel in a JFrame and in the panel I can draw a continuous line by pressing buttons, but whenever I resize the window, the lines disappear. How can I stop this?
Ernest Friedman-Hill
author and iconoclast

Joined: Jul 08, 2003
Posts: 24195

Hi Kristo,

Welcome to JavaRanch!

You have to save the line in some form as you draw it, and then just paint it in your paintComponent() method(). This method will be called as necessary to redraw the line. So, for example, each time you press a button, you might add a set of coordinates to an array. The paintComponent() method would read all those coordinates from the array and draw the line. Every time it's called it can redraw the whole line.

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It is sorta covered in the JavaRanch Style Guide.
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