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所以我有以下代码，每当我按下方形工具按钮时，它应该在 JTextFields 所说的地方绘制一个正方形。但是由于某种原因，JTextField 值不起作用，并且无法绘制正方形...这是正方形代码和 JTextField：

JTextField 的初始化

        squareX = new JTextField(3);
        squareY = new JTextField(3);
        squareW = new JTextField(3);
        squareH = new JTextField(3);

动作监听器：

        squareX.addActionListener(listener);
        squareY.addActionListener(listener);
        squareW.addActionListener(listener);
        squareH.addActionListener(listener);

这是我将它们的值设置为文本的地方：

        x = Integer.parseInt(op.squareX.getText());
        y = Integer.parseInt(op.squareY.getText());
        w = Integer.parseInt(op.squareW.getText());
        h = Integer.parseInt(op.squareH.getText());
        g.fillRect(x,y,w,h);

如果这很重要，那就是错误所说的

Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: ""
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
    at java.lang.Integer.parseInt(Integer.java:470)
    at java.lang.Integer.parseInt(Integer.java:499)
    at com.theDevCorner.Game$GridPane.paintComponent(Game.java:155)
    at javax.swing.JComponent.paint(JComponent.java:1037)
    at javax.swing.JComponent._paintImmediately(JComponent.java:5106)
    at javax.swing.JComponent.paintImmediately(JComponent.java:4890)
    at javax.swing.RepaintManager$3.run(RepaintManager.java:814)
    at javax.swing.RepaintManager$3.run(RepaintManager.java:802)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:802)
    at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:745)
    at javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:725)
    at javax.swing.RepaintManager.access$1000(RepaintManager.java:46)
    at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1684)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:708)
    at java.awt.EventQueue.access$400(EventQueue.java:82)
    at java.awt.EventQueue$2.run(EventQueue.java:669)
    at java.awt.EventQueue$2.run(EventQueue.java:667)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:678)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:296)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:211)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:196)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:188)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
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1 回答 1

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构造函数JTextField(int)指定列数而不是初始值。因此，JTextComponent's文本值在传递给 时仍然为空Integer#parseInt。因此，您可以改用指定初始值的构造函数：

squareX = new JTextField("3");
squareY = new JTextField("3");
squareW = new JTextField("3");
squareH = new JTextField("3");
于 2013-05-12T03:14:08.630 回答