When creating an instance of AbstractRegionPainter and then trying to invoke decodeX(), decodeY(), decodeAnchorY() etc. methods a NullPointerException is thrown.

Please see the following code sample:

import javax.swing.*;
import java.awt.*;

public class TestARP {

    public static void main(String[] args) {
        class MyARP extends javax.swing.plaf.nimbus.AbstractRegionPainter {
            protected PaintContext getPaintContext() {
                return null;
            }
            protected void doPaint(Graphics2D g, JComponent c,
                                   int width, int height,
                                   Object[] extendedCacheKeys) {
            }
            public void callDecodeAnchorX() {
                decodeX(0.5f);
            }
        }
        new MyARP().callDecodeAnchorX();
    }
}
-----------------------------------------
output will be:

Exception in thread "main" java.lang.NullPointerException
at javax.swing.plaf.nimbus.AbstractRegionPainter$PaintContext.access$100(AbstractRegionPainter.java:472)
at javax.swing.plaf.nimbus.AbstractRegionPainter.decodeX(AbstractRegionPainter.java:233)
at TestARP$1MyARP.callDecodeAnchorX(TestARP.java:16)
at TestARP.main(TestARP.java:19)