Ich erhalte bei folgendem Code folgende Fehler:
Fehler:
Wie löse ich das Problem?
Java:
mport javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
/**
* Created by kanda on 16.05.17.
*/
public class PlayGround {
private JPanel jPanel2;
private JButton button1;
private Spielkarte[][] Spielfeld = new Spielkarte[3][3];
public PlayGround() {
button1.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent actionEvent) {
generate();
}
});
}
public void generate() {
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 3; j++) {
Spielfeld[i][j] = new Spielkarte();
Spielfeld[i][j].setBounds(50 + (i * 30), 80 + (j * 30), 30, 30);
Spielfeld[i][j].setBackground(new Color(0, 0, 0));
Spielfeld[i][j].setForeground(new Color(0, 0, 0));
Spielfeld[i][j].setMargin(new Insets(2, 2, 2, 2));
Spielfeld[i][j].setText("");
jPanel2.add(Spielfeld[i][j]);
}
}
}
public static void main(String[] args) {
JFrame frame = new JFrame("PlayGround");
frame.setContentPane(new PlayGround().jPanel2);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
}
}
Fehler:
Code:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at com.intellij.uiDesigner.core.GridLayoutManager.addLayoutComponent(GridLayoutManager.java:134)
at java.awt.Container.addImpl(Container.java:1127)
at java.awt.Container.add(Container.java:417)
at PlayGround.generate(PlayGround.java:33)
at PlayGround$1.actionPerformed(PlayGround.java:19)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6533)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
at java.awt.Component.processEvent(Component.java:6298)
at java.awt.Container.processEvent(Container.java:2236)
at java.awt.Component.dispatchEventImpl(Component.java:4889)
at java.awt.Container.dispatchEventImpl(Container.java:2294)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)
at java.awt.Container.dispatchEventImpl(Container.java:2280)
at java.awt.Window.dispatchEventImpl(Window.java:2746)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:90)
at java.awt.EventQueue$4.run(EventQueue.java:731)
at java.awt.EventQueue$4.run(EventQueue.java:729)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
Wie löse ich das Problem?