Java:在Eclipse中调用另一个类时出错

//我设法修复了它，有一个完全不相关的错误，它不是作为错误给出的，我删除了代码，现在它工作了。谢谢你抽出时间

嗨，
我在Eclipse中创建了一个Java程序，该程序运行良好，尽管我的类中有一个错误，但稍后我将在代码中显示它。我有一个文件夹类，它使用Document类并在单击菜单中的按钮时创建一个新的文件夹类。这曾经工作得很好，但是昨天Eclipse和我的pc发生了一些奇怪的事情，现在它无法工作，即使代码没有一点变化

如果你需要额外的信息或者我觉得问题不对，就说出来。这是我的第一个问题。我还在学习

//编辑 当我将鼠标悬停在Document.java（公共类文档扩展JInternalFrame实现ActionListener）中的错误上时，它会说：

The type Document must implement the inherited abstract method ActionListener.actionPerformed(ActionEvent)

但当我把它抽象化时，它只会产生更多的错误

Folder.java

import javax.swing.*;
import javax.swing.text.*;

import java.io.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.Font.*;
import java.util.*;

//Main screen

public class Folder extends JFrame implements ActionListener {
    public ImageIcon img = new ImageIcon("C:/users/jeroe_000/pictures/flogo.png");
    private JFrame JFrame = new JFrame();
    private JMenuBar mb = new JMenuBar();
    private JMenu men = new JMenu("Window");
    private JMenuItem newItem = new JMenuItem("New window");
    private JMenuItem closeItem = new JMenuItem("Close all windows");
    private JMenuItem exit = new JMenuItem("Close");
    public JPanel startscreen = new JPanel();

    public boolean opened = false;

    public String programName = "Sitebucket Office";


    private JDesktopPane bord = new JDesktopPane();
    private int n; //number of internal windows 



    private Folder() {      
        setContentPane(bord);
        setJMenuBar(mb);
        mb.add(men);
        men.add(newItem); men.add(closeItem); men.addSeparator(); men.add(exit);
        Container contentPane = getContentPane();

        //connect listener to the menu alternatives
        newItem.addActionListener(this);
        closeItem.addActionListener(this);
        exit.addActionListener(this);
        setTitle("Sitebucket Office");
        setSize(900, 700);
        setVisible(true);
        setDefaultCloseOperation(EXIT_ON_CLOSE);

        startscreen.setVisible(true);
        JLabel welcome = new JLabel("Welcome to Sitebucket Office");
        contentPane.add(startscreen);
        startscreen.add(welcome, BorderLayout.SOUTH);


        //Opmaak

        bord.setPreferredSize(new Dimension(100, 25));
        bord.setBackground(new Color(58, 119, 165, 70 ));
        bord.setForeground(new Color(255, 255, 255));

        mb.setBackground(new Color(58, 119, 165));
        mb.setForeground(new Color(255, 255, 255));

        men.setBackground(new Color(58, 119, 165));
        men.setForeground(new Color(255, 255, 255));
        men.setFont(new Font("Oxygen Light", Font.PLAIN,  20));

        newItem.setBackground(new Color(58, 119, 165));
        newItem.setForeground(new Color(255, 255, 255));
        newItem.setFont(new Font("Oxygen Light", Font.PLAIN, 14));

        closeItem.setBackground(new Color(58, 119, 165));
        closeItem.setForeground(new Color(255, 255, 255));
        closeItem.setFont(new Font("Oxygen Light", Font.PLAIN, 14));

        exit.setBackground(new Color(58, 119, 165));
        exit.setForeground(new Color(255, 255, 255));
        exit.setFont(new Font("Oxygen Light", Font.PLAIN, 14));
    }



    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == newItem) {
            Document f = new  Document("Document " + (n+1));
            bord.add(f);
            int x = Math.min(30*n, bord.getWidth() - f.getWidth());
            int y = Math.min(30*n, bord.getHeight() - f.getHeight());
            f.setLocation(x, y);

            f.moveToFront();
            n++;
        }

        else if (e.getSource() == closeItem) {
            JInternalFrame[] a = bord.getAllFrames();
            for (int i=0; i<a.length; i++)
                a[i].dispose();
            n = 0;
        }

        else if (e.getSource() == exit){
            System.exit(0);
        }
    }

    public static void main (String arg[]) {
        new Folder();
    }

}

IntPaintWindow.java

import javax.swing.*;
import java.awt.*;

public class IntPaintWindow extends JInternalFrame{
    public IntPaintWindow(String title){
        super(title, true, true, true, true);
        setSize(400, 300);
        setVisible(true);

    }
}

错误

我知道这是很多信息，但如果你们能帮我修复这个错误，我将非常感激

---

您好，Jeroen

尝试更改文档类的名称“未解决的编译问题”意味着您的源文件和编译的类文件不同步。删除所有已编译的类文件并重新编译所有源文件。可能它认为您指的是java.swing.text.Document，而不是名为Document的类。更改名称不起作用。@iJeroen然后是什么问题？单击该行右侧的符号，然后单击

添加未混合方法

import javax.swing.*;
import java.awt.*;

public class IntPaintWindow extends JInternalFrame{
    public IntPaintWindow(String title){
        super(title, true, true, true, true);
        setSize(400, 300);
        setVisible(true);

    }
}

Exception in thread "AWT-EventQueue-0" java.lang.Error: Unresolved compilation problem: 
    Cannot instantiate the type Document

    at Folder.actionPerformed(Folder.java:84)
    at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
    at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
    at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
    at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
    at javax.swing.AbstractButton.doClick(Unknown Source)
    at javax.swing.plaf.basic.BasicMenuItemUI.doClick(Unknown Source)
    at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(Unknown Source)
    at java.awt.Component.processMouseEvent(Unknown Source)
    at javax.swing.JComponent.processMouseEvent(Unknown Source)
    at java.awt.Component.processEvent(Unknown Source)
    at java.awt.Container.processEvent(Unknown Source)
    at java.awt.Component.dispatchEventImpl(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Window.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    at java.awt.EventQueue.access$400(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue$4.run(Unknown Source)
    at java.awt.EventQueue$4.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)