Question

所以我制作了这个非常简单的程序，在应用程序完美运行50个单词之后放置字符串“50”。问题就在这里：

if(words == 50){
    text.insert("50", words * charsa);
}

这是测试代码：

package wordscount;
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;

/**
 *
 * @author Shady Kamal
 * 
 */

public class WordsCount {

    boolean working;
    int words = 0;
    int wordneed = 50;
    int charsa;
    JTextArea text = new JTextArea(600, 600);
    JFrame frame = new JFrame("Counter for fast reading");
    JButton launch = new JButton("Start");
    String atext;
    boolean isword;

   public WordsCount(){
       frame.setSize(700, 700);
       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

       launch.addActionListener(new ActionListener(){

           @Override
           public void actionPerformed(ActionEvent e) {

               words = 0;
               atext = text.getText();
               charsa = atext.length();

               for (int i = 0; i < charsa; i++) {

                   if ( Character.isLetter(atext.charAt(i)) == false ){
                       isword = false;
                   }else if (i == 0){
                       isword = true;
                   }else if ( Character.isLetter(atext.charAt(i-1)) ){
                       isword = false;
                   }else if ( atext.charAt(i-1) == '\'' && i > 1 && 
                              Character.isLetter(atext.charAt(i-2)) ){
                       isword = false;
                    }else{
                       isword = true;
                    }

                    if (isword){
                       words++;
                       if(words == 50){
                           text.insert("50", words * charsa);
                       }
                    }
                }
                System.out.println("Chars:" + charsa);
                System.out.println("Words:" + words);
            }
        });

        frame.add(text, BorderLayout.CENTER);
        frame.getContentPane().add(new JScrollPane(text),BorderLayout.CENTER);
        frame.add(launch, BorderLayout.SOUTH);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public static void main(String[] args) {

        JOptionPane.showMessageDialog(null, "" + "Instructions: \n" +
            "_________________________________________\n" +
            "Just paste text right here in the TextBox\n" +
            "and click the \"Start\" button when your'e ready\n" +
             "the program will do the rest.\n");
        new WordsCount();
    }
}

当我运行它并写出50或以上的单词时会抛出这个错误（其中的反讽是它最后说的“Build Sucessfull”，它对我来说似乎并不是那么成功[甚至它在构建编译和运行时工作并没有失败]这仍然是处理3行代码的巨大错误！）

run:
Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: Invalid insert
at javax.swing.JTextArea.insert(JTextArea.java:461)
at wordscount.WordsCount$1.actionPerformed(WordsCount.java:66)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$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:3320)
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:735)
at java.awt.EventQueue.access$200(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:694)
at java.awt.EventQueue$3.run(EventQueue.java:692)
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:708)
at java.awt.EventQueue$4.run(EventQueue.java:706)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:705)
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)
BUILD SUCCESSFUL (total time: 21 seconds)

Answer 1

这是一个运行时错误，即使您的代码编译没有错误，它仍然可能发生。

Javadocs for the insert method州：

抛出：

IllegalArgumentException - 如果pos是模型中的无效位置

words * charsa（尚未）您的排名JTextArea不得存在。确保位置已经存在或修改位置的公式，使其指向现有位置。

Answer 2

insert给你错误，因为charsa是JTextArea的大小，你甚至将它倍增，所以它明显超过JTextArea大小。

我想这就是你想要的。试一试：

    @Override
    public void actionPerformed(ActionEvent e) {

    int wordsSize = 0;
    words = 0;
    atext = text.getText();
    charsa = atext.length();


    for (int i = 0; i < charsa; i++) {

        wordsSize++;

        if(! Character.isLetter(atext.charAt(i)) && Character.isLetter(atext.charAt(i-1)))
        {
            isword = true;
        }

        else
        {
            isword= false;
        }

        if (isword){
            words++;
            if(words == 50){
                text.insert("50", wordsSize);
            }
        }
    }
    System.out.println("Chars:" + charsa);
    System.out.println("Words:" + words);

    }

为什么我不能在JTextArea中插入String？

2 个答案: