如何使用按钮从另一个类调用方法?

时间:2013-05-18 21:26:18

标签: java swing methods

我是Java的新手,我正在努力创建一个基本的UI。我可以使用JButtons轻松调用JOptionPanes,但我不能做的是使用它们从另一个类调用任何东西。

目前我有我的主类,我的UI类和处理我数据的类。

在我处理数据的类中,我有一个方法对数组的2个元素执行基本求和:

    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,我会得到更多我能忍受的例外情况。有什么想法吗?

很抱歉,如果这是一个非常基本的问题。

编辑,这是我点击按钮时获得的例外情况:

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)

2 个答案:

答案 0 :(得分:1)

在您的主要课程中,这一行 - ans=String.format("The sum of day1 and day2 is: %s", sum);

为什么使用%s,这意味着String变量,sumint。请改用%d

还有sortedData[0][0][0]sortedData[0][0][1]中存储的值是什么?

答案 1 :(得分:1)

鉴于Integer.parseInt采用String参数,可以说sortedData是一个3D String数组。从堆栈跟踪中,数组sortedData已初始化,但各个元素不是

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Integer.parseInt之前已为这些元素指定了值。

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
      }
   }
}