- LightI3ulb
- Oct 28, 2006
-
Standard pleasure model.
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I hata Java. Can someone explain to me why Java keeps spitting out:
code:Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at Whiteboard.<init>(Whiteboard.java:16)
at Whiteboard.createAndShowGUI(Whiteboard.java:82)
at Whiteboard.access$0(Whiteboard.java:75)
at Whiteboard$1.run(Whiteboard.java:21)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)
code:import javax.swing.*;
import java.awt.GridBagLayout;
import java.awt.GridBagConstraints;
import java.awt.Insets;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.event.MouseListener;
import java.awt.event.MouseEvent;
public class Whiteboard extends JPanel implements MouseListener {
Drawspace drawSpace;
JTextArea textArea;
Graphics2D g = (Graphics2D) drawSpace.getGraphics();
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
public Whiteboard() {
super(new GridBagLayout());
GridBagLayout gridbag = (GridBagLayout)getLayout();
GridBagConstraints c = new GridBagConstraints();
c.fill = GridBagConstraints.VERTICAL;
c.gridwidth = GridBagConstraints.REMAINDER;
c.weightx = 1.0;
c.weighty = 1.0;
c.insets = new Insets(1, 1, 1, 1);
drawSpace = new Drawspace(new Color(0.98f, 0.97f, 0.85f));
c.anchor = GridBagConstraints.NORTHWEST;
gridbag.setConstraints(drawSpace, c);
add(drawSpace);
JButton drawRectangle = new JButton("Rectangle");
drawRectangle.setHorizontalAlignment(JButton.RIGHT);
add(drawRectangle);
setPreferredSize(new Dimension(450, 450));
setBorder(BorderFactory.createEmptyBorder(20,20,20,20));
}
public void mousePressed(MouseEvent e) {
g.drawLine((e.getX()), (e.getY()), ((e.getX())+1), ((e.getY())+1));
g.dispose();
}
public void mouseReleased(MouseEvent e) {
}
public void mouseEntered(MouseEvent e) {
}
public void mouseExited(MouseEvent e) {
}
public void mouseClicked(MouseEvent e) {
g.drawLine((e.getX()), (e.getY()), ((e.getX())+1), ((e.getY())+1));
g.dispose();
}
private static void createAndShowGUI() {
JFrame.setDefaultLookAndFeelDecorated(true);
JFrame frame = new JFrame("Whiteboard");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JComponent newContentPane = new Whiteboard();
newContentPane.setOpaque(true);
frame.setContentPane(newContentPane);
frame.pack();
frame.setVisible(true);
}
}
code:import javax.swing.*;
import java.awt.Dimension;
import java.awt.Color;
public class Drawspace extends JLabel {
Dimension minSize = new Dimension(100, 100);
public Drawspace(Color color) {
setBackground(color);
setOpaque(true);
setBorder(BorderFactory.createLineBorder(Color.black));
}
public Dimension getMinimumSize() {
return minSize;
}
public Dimension getPreferredSize() {
return minSize;
}
}
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#
¿
Apr 20, 2008 18:33
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Apr 20, 2008 18:33
