1

我对Java很陌生,我正在尝试制作一个基本的用户界面。我可以使用 JButtons 轻松调用 JOptionPanes,但我不能使用它们从另一个类中调用任何内容。

目前我有我的主类、我的 UI 类和处理我的数据的类。

在我处理我的数据的类中,我有一个对数组的两个元素执行基本求和的方法:

    public void firstMonth(){
        String ans;
        int num1 = Integer.parseInt(sortedData[0][0][0]);
        int num2 = Integer.parseInt(sortedData[0][0][1]);
        int sum = num1 * num2;

        ans=String.format("The sum of day1 and day2 is: %s", sum);
        JOptionPane.showMessageDialog(null, ans, "Title", JOptionPane.PLAIN_MESSAGE);

    }

然后在我的 UI 类中,我尝试在按下其中一个按钮时调用它:

public class UserInterface extends JFrame {

GetData a = new GetData();

    private class myhandler implements ActionListener{

        public void actionPerformed(ActionEvent event){

            if(event.getSource()==button1){
                a.firstMonth();

            }
}
}

但是当我按下按钮时,我会得到更多我可以忍受的例外情况。有任何想法吗?

对不起,如果这是一个非常基本的问题。

编辑,这是我单击按钮时遇到的异常:

Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: null
    at java.lang.Integer.parseInt(Integer.java:454)
    at java.lang.Integer.parseInt(Integer.java:527)
    at pkg110_term3.GetData.firstMonth(GetData.java:75)
    at pkg110_term3.UserInterface$myhandler.actionPerformed(UserInterface.java:71)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
    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:6505)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
    at java.awt.Component.processEvent(Component.java:6270)
    at java.awt.Container.processEvent(Container.java:2229)
    at java.awt.Component.dispatchEventImpl(Component.java:4861)
    at java.awt.Container.dispatchEventImpl(Container.java:2287)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
    at java.awt.Container.dispatchEventImpl(Container.java:2273)
    at java.awt.Window.dispatchEventImpl(Window.java:2719)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:729)
    at java.awt.EventQueue.access$200(EventQueue.java:103)
    at java.awt.EventQueue$3.run(EventQueue.java:688)
    at java.awt.EventQueue$3.run(EventQueue.java:686)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
    at java.awt.EventQueue$4.run(EventQueue.java:702)
    at java.awt.EventQueue$4.run(EventQueue.java:700)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:699)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
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2 回答 2

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在你的主类中,这一行 -ans=String.format("The sum of day1 and day2 is: %s", sum);

你为什么使用%s,这意味着一个字符串变量并且sum是一个int. 改为使用%d

还有存储在sortedData[0][0][0]和中的值是什么sortedData[0][0][1]

于 2013-05-18T21:36:00.827 回答
1

鉴于Integer.parseInt接受一个String参数,可以肯定地说这sortedData是一个 3DString数组。从您的堆栈跟踪中,数组sortedData已初始化,但各个元素初始化。

Object类型的默认值为null。这同样适用于Object数组中的值。

确保在调用之前已为这些元素分配了值Integer.parseInt

for (int i=0; i < sortedData.length; i++) {
   for (int j=0; j < sortedData[i].length; j++) {
      for (int k=0; k < sortedData[i][j].length; k++) {
         sortedData[i][j][k] = ... // some string
      }
   }
}
于 2013-05-18T21:42:48.583 回答