###前提・実現したいこと
javaでlauncherを開発しています。 ボタンを右クリックしたときに JMenuを表示しようとしたときに 以下のようなエラーメッセージが発生しました。 よろしくお願いいたします。
###発生している問題・エラーメッセージ
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at listener.PopupListener.mouseReleased(PopupListener.java:67) at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:290) 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:76) at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86) 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:76) 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)
###該当のソースコード
java
1//CreateMenuクラス一部抜粋 2public class CreateMenu { 3 JPopupMenu menu; 4 JMenuItem change; 5 JMenuItem delete; 6 7 public void createMenu(){ 8 menu = new JPopupMenu(); 9 change = new JMenuItem("変更"); 10 change.addMouseListener(new MenuListener()); 11 delete = new JMenuItem("削除"); 12 delete.addMouseListener(new MenuListener()); 13 menu.add(change); 14 menu.add(delete); 15 16 } 17} 18 19//PopupListenerクラス一部抜粋 20public class PopupListener implements MouseListener{ 21 public void mousePressed(MouseEvent e) { 22 23 if (e.isPopupTrigger()) { 24 CreateMenu crtMenu = new CreateMenu(); 25 JPopupMenu menu = crtMenu.getMenu(); 26 menu.show(e.getComponent(), e.getX(), e.getY()); 27 e.consume(); 28 } 29} 30 31//mainクラス一部抜粋 32 33 for(int i=0;i<button.length;i++){ 34 button[i].addActionListener(new ClickListener()); 35 button[i].addMouseListener(new PopupListener()); 36 panel.add(button[i]); 37 }
###試したこと
e.getComponent()ができてないと思ったので 別の方法も試してみたのですが 同じエラーが出てしまいました。 試したソースは以下の通りです。 public void mousePressed(MouseEvent e) { if (e.isPopupTrigger()) { CreateMenu crtMenu = new CreateMenu(); JPopupMenu menu = crtMenu.getMenu(); System.out.println(e.getX()); System.out.println(e.getY()); System.out.println(e.getSource()); JComponent comp = (JComponent)e.getSource(); menu.show(comp, e.getX(), e.getY()); e.consume(); } }
回答2件
あなたの回答
tips
プレビュー
バッドをするには、ログインかつ
こちらの条件を満たす必要があります。