0

Naはパラメータです。このパラメータは正しいと確信しています。Na JTextFieldの配列を宣言しましたが、そのうちの1つを使用したいと思います。しかし、コードを実行すると、例外があります...

それが私のコードです：

import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

class Panneau_fenetre1A extends JPanel                      
{   
    public Panneau_fenetre1A(int Na)
    {
        JTextField[] allField = new JTextField [Na];
        for(int i = 0;i<Na;i++)
        {
            allField[i].setText(String.valueOf(0));
            allField[i].setBounds(150, 350+i*25,20, 20);
        }
    }

}

それは例外です：

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at Panneau_fenetre1A.<init>(Panneau_fenetre1A.java:18)
    at Cadre_fenetre1A.<init>(Cadre_fenetre1A.java:13)
    at Panneau_fenetre$ecout1.actionPerformed(Panneau_fenetre.java:64)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2012)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2335)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:404)
    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:6268)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
    at java.awt.Component.processEvent(Component.java:6033)
    at java.awt.Container.processEvent(Container.java:2045)
    at java.awt.Component.dispatchEventImpl(Component.java:4629)
    at java.awt.Container.dispatchEventImpl(Container.java:2103)
    at java.awt.Component.dispatchEvent(Component.java:4455)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4633)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4297)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4227)
    at java.awt.Container.dispatchEventImpl(Container.java:2089)
    at java.awt.Window.dispatchEventImpl(Window.java:2517)
    at java.awt.Component.dispatchEvent(Component.java:4455)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:649)
    at java.awt.EventQueue.access$000(EventQueue.java:96)
    at java.awt.EventQueue$1.run(EventQueue.java:608)
    at java.awt.EventQueue$1.run(EventQueue.java:606)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:105)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:116)
    at java.awt.EventQueue$2.run(EventQueue.java:622)
    at java.awt.EventQueue$2.run(EventQueue.java:620)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:105)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:619)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:275)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:200)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:190)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:185)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:177)
4

2 に答える 2

2

アレイを適切に初期化できませんでした。したがって、allField[i] = nullすべてのi < Na。したがって、NullPointerException。以下が機能します、

for(int i = 0;i < Na;i++)
{
    JTextField textField = new JTextField(String.valueOf(0));
    textField.setBounds(150, 350 + i * 25, 20, 20);
    allField[i] = textField;
}
于 2012-08-07T18:21:12.180 に答える
0

この行...

JTextField[] allField = new JTextField [Na];

JTextFieldオブジェクトを保持する新しいARRAYを初期化します。配列には-Na-スペースが含まれていますが、各スペースはまだ空です。空の配列スペースに入るには、JTextFieldオブジェクトを作成する必要があります。

このようなものが機能するはずです...

for(int i = 0;i < Na;i++)
{
    allField[i] = new JTextField(String.valueOf(0));
    allField[i].setBounds(150, 350 + i * 25, 20, 20);

}
于 2012-08-07T18:26:04.190 に答える