java - 组布局错误: can't find wrong line

Question

package edu.uga.cs1302.gui;
import java.awt.event.*;
import java.io.*;
import java.text.ParseException;
import java.util.ArrayList;
import javax.swing.*;


public class StudentDirectory extends JFrame implements ActionListener{

private static final long serialVersionUID = 3294408483853747952L;
private Student current;
private ArrayList<Student> data;
private ArrayList<Student> unsavedData;
private ObjectOutputStream oos;
private FileOutputStream fos;


    public StudentDirectory() throws FileNotFoundException{
        JFrame frame = new JFrame("Student Directory");

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);
    frame.setSize(300,300);

    data = new ArrayList<Student>();
    unsavedData = new ArrayList<Student>();
    current = new Student();
    unsavedData.add(current);
    try {
        fos = new FileOutputStream("StudentsList.dat");
        oos = new ObjectOutputStream(fos);
    } catch (IOException e1) {
        e1.printStackTrace();
    }

    JMenuBar mb = new JMenuBar();
    JMenu file = new JMenu("File");
    JMenuItem load = new JMenuItem("Load");
    JMenuItem save = new JMenuItem("Save");
    JMenuItem exit = new JMenuItem("Exit");

    file.add(load);
    file.add(save);
    file.addSeparator();
    file.add(exit);
    mb.add(file);
    frame.setJMenuBar(mb);

    JPanel Pane = (JPanel) frame.getContentPane();
    GroupLayout layout = new GroupLayout(Pane);
    Pane.setLayout(layout);
    layout.setAutoCreateGaps(true);
    layout.setAutoCreateContainerGaps(true);

    JLabel ID = new JLabel("ID:");
    JTextField IDn = new JTextField();
    IDn.setEditable(true);

    JLabel first = new JLabel("First Name:");
    JTextField firstN = new JTextField();
    firstN.setEditable(true);

    JLabel last = new JLabel("Last Name:");
    JTextField lastN = new JTextField();
    lastN.setEditable(true);

    JLabel DOB = new JLabel("Date of Birth:");
    JTextField dateN = new JTextField();
    dateN.setEditable(true);

    JLabel college = new JLabel("College:");
    JTextField collegeN = new JTextField();
    collegeN.setEditable(true);

    JButton prev = new JButton("Previous");
    JButton next = new JButton("Next");
    JButton append = new JButton("Append");

    prev.setEnabled(false);

    layout.setHorizontalGroup(layout.createSequentialGroup()
            .addGroup(layout.createParallelGroup(GroupLayout.Alignment.TRAILING)
                .addComponent(ID)
                .addComponent(first)
                .addComponent(last)
                .addComponent(DOB)
                .addComponent(college)
                .addComponent(prev))
            .addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
                .addComponent(IDn)
                .addComponent(firstN)
                .addComponent(lastN)
                .addComponent(dateN)
                .addComponent(collegeN)
                .addGroup(layout.createSequentialGroup()
                        .addComponent(next)
                        .addComponent(append))
                )
            );

    layout.setVerticalGroup(layout.createSequentialGroup()
            .addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                    .addComponent(ID)
                    .addComponent(IDn))
            .addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                    .addComponent(first)
                    .addComponent(firstN))
            .addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                    .addComponent(last)
                    .addComponent(lastN))
            .addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                    .addComponent(DOB)
                    .addComponent(dateN))
            .addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                    .addComponent(college)
                    .addComponent(collegeN))
            .addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                    .addComponent(prev)
                    .addComponent(next)
                    .addComponent(append))
        );

        exit.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                dispose();
                System.exit(0);
            }
          }
        );
        load.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e){
                try {
                    fos = new FileOutputStream("StudentsList.dat");
                    oos.reset();
                    for(int i = 0; i < data.size();i++){
                        oos.writeObject(data.get(i));
                    }
                } catch (IOException e1) {
                    e1.printStackTrace();
                }

            }
        });

        save.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e){
                try {
                    oos.flush();
                    oos.close();
                } catch (IOException e1) {
                    e1.printStackTrace();
                }
            }
        });

        IDn.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                int index = unsavedData.indexOf(current);
                unsavedData.remove(index);
                String num = IDn.getText();
                int idInput = Integer.parseInt(num);
                current.setID(idInput);
                unsavedData.add(index, current);

            }

        });

        firstN.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                int index = unsavedData.indexOf(current);
                unsavedData.remove(index);
                String currentFirst = firstN.getText();
                current.setFirst(currentFirst);
                unsavedData.add(index, current);
            }
        });

        lastN.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                int index = unsavedData.indexOf(current);
                unsavedData.remove(index);
                String currentLast = lastN.getText();
                current.setLast(currentLast);
                unsavedData.add(index, current);
            }
        });

        dateN.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                int index = unsavedData.indexOf(current);
                unsavedData.remove(index);
                String currentDOB = dateN.getText();
                try {
                    current.setDOB(currentDOB);
                } catch (ParseException e1) {
                    e1.printStackTrace();
                }
                unsavedData.add(index, current);
            }
        });

        collegeN.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                int index = unsavedData.indexOf(current);
                unsavedData.remove(index);
                String currentCollege = collegeN.getText();
                current.setCollege(currentCollege);
                unsavedData.add(index, current);
            }
        });

        prev.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e){
                int index = unsavedData.indexOf(current);
                if(index!=0)
                    if(index-1==0){
                        prev.setEnabled(false);
                    }
                    current= unsavedData.get(index-1);
                    IDn.cut();
                    IDn.setText(""+current.getID());
                    firstN.cut();
                    firstN.setText(current.getFirst());
                    lastN.cut();
                    lastN.setText(current.getLast());
                    dateN.cut();
                    dateN.setText(current.getDOB());
                    collegeN.cut();
                    collegeN.setText(current.getCollege());
            }

        });

        next.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                prev.setEnabled(true);
                int index = unsavedData.indexOf(current);
                if(index+1< unsavedData.size()){
                    current = unsavedData.get(index+1);
                    IDn.cut();
                    IDn.setText(""+current.getID());
                    firstN.cut();
                    firstN.setText(current.getFirst());
                    lastN.cut();
                    lastN.setText(current.getLast());
                    dateN.cut();
                    dateN.setText(current.getDOB());
                    collegeN.setText(current.getCollege());
                }else{
                    current = new Student();
                    IDn.setText("");
                    firstN.setText("");
                    lastN.setText("");
                    dateN.setText("");
                    collegeN.setText("");
                    unsavedData.add(current);
                }
                index++;
            }
        });

        append.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                data = new ArrayList<Student>();
                for(int x = 0;x<unsavedData.size();x++){
                    data.add(unsavedData.get(x));
                }
            }
        });



        frame.pack();
        frame.setVisible(true);
        frame.validate();


}
@Override
public void actionPerformed(ActionEvent e) {
    // TODO Auto-generated method stub

}
}

主要方法

package edu.uga.cs1302.gui;
import java.io.FileNotFoundException;
import javax.swing.JFrame;

public class StudentMain {
    public static void main(String[] args) throws FileNotFoundException{
        new StudentDirectory();
    }
}

当我使用“上一个”按钮时发生错误。

Exception in thread "AWT-EventQueue-0" java.lang.IllegalStateException: javax.swing.JTextField[,0,0,0x0,invalid,layout=javax.swing.plaf.basic.BasicTextUI$UpdateHandler,alignmentX=0.0,alignmentY=0.0,border=com.apple.laf.AquaTextFieldBorder@154fd2c3,flags=288,maximumSize=,minimumSize=,preferredSize=,caretColor=javax.swing.plaf.ColorUIResource[r=0,g=0,b=0],disabledTextColor=javax.swing.plaf.ColorUIResource[r=128,g=128,b=128],editable=true,margin=javax.swing.plaf.InsetsUIResource[top=0,left=0,bottom=0,right=0],selectedTextColor=com.apple.laf.AquaImageFactory$SystemColorProxy[r=0,g=0,b=0],selectionColor=com.apple.laf.AquaImageFactory$SystemColorProxy[r=164,g=205,b=255],columns=0,columnWidth=0,command=,horizontalAlignment=LEADING] is not attached to a vertical group
    at javax.swing.GroupLayout.checkComponents(GroupLayout.java:1090)
    at javax.swing.GroupLayout.prepare(GroupLayout.java:1040)
    at javax.swing.GroupLayout.layoutContainer(GroupLayout.java:910)
    at java.awt.Container.layout(Container.java:1510)
    at java.awt.Container.doLayout(Container.java:1499)
    at java.awt.Container.validateTree(Container.java:1695)
    at java.awt.Container.validateTree(Container.java:1704)
    at java.awt.Container.validateTree(Container.java:1704)
    at java.awt.Container.validate(Container.java:1630)
    at javax.swing.RepaintManager$3.run(RepaintManager.java:711)
    at javax.swing.RepaintManager$3.run(RepaintManager.java:709)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
    at javax.swing.RepaintManager.validateInvalidComponents(RepaintManager.java:708)
    at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1731)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
    at java.awt.EventQueue.access$500(EventQueue.java:97)
    at java.awt.EventQueue$3.run(EventQueue.java:709)
    at java.awt.EventQueue$3.run(EventQueue.java:703)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
    at     java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at java.util.Calendar.setTime(Calendar.java:1770)
    at java.text.SimpleDateFormat.format(SimpleDateFormat.java:943)
    at java.text.SimpleDateFormat.format(SimpleDateFormat.java:936)
    at java.text.DateFormat.format(DateFormat.java:345)
    at edu.uga.cs1302.gui.Person.getDOB(Person.java:50)
    at edu.uga.cs1302.gui.StudentDirectory$9.actionPerformed(StudentDirectory.java:234)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
    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:6535)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
    at java.awt.Component.processEvent(Component.java:6300)
    at java.awt.Container.processEvent(Container.java:2236)
    at java.awt.Component.dispatchEventImpl(Component.java:4891)
    at java.awt.Container.dispatchEventImpl(Container.java:2294)
    at java.awt.Component.dispatchEvent(Component.java:4713)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)
    at java.awt.Container.dispatchEventImpl(Container.java:2280)
    at java.awt.Window.dispatchEventImpl(Window.java:2750)
    at java.awt.Component.dispatchEvent(Component.java:4713)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
    at java.awt.EventQueue.access$500(EventQueue.java:97)
    at java.awt.EventQueue$3.run(EventQueue.java:709)
    at java.awt.EventQueue$3.run(EventQueue.java:703)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
    at java.awt.EventQueue$4.run(EventQueue.java:731)
    at java.awt.EventQueue$4.run(EventQueue.java:729)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

我的 Student 类有几个参数(字符串名字、字符串姓氏、字符串日期、字符串大学、int ID)

在构造函数中将日期转换为简单日期格式(MM-dd-yyyy)的日期(可能是错误之一)

我的代码的要点:应该将学生的 ArrayList 加载到内存中。应显示 ArrayList w GUI 的第一个学生的信息。信息导出到“StudentsList.dat”文件。单击“追加”按钮时保存到文件。"file"菜单包含三个菜单项:“加载”、“保存”、“退出”。“Load”将上面文件中的 Students ArrayList 加载到内存中。“保存”将学生的 ArrayList 保存到上述文件中。“退出”终止程序。“上一个”按钮返回到 ArrayList 中的上一个 Student。如果我们位于 ArrayList 的开头，则应禁用此按钮。“Next”按钮显示 ArrayList 中的下一个 Student。如果我们位于 ArrayList 的末尾，则应禁用此按钮。

Answer 1

我再次建议您按照 Swing 文档建议从 Swing 事件线程调用 GUI。例如:

public static void main(String[] args) {
    SwingUtilities.invokeLater(() -> {
        // this is inside a "lambda" Runnable
        try {
            new StudentDirectory();
        } catch (Exception e) {
            e.printStackTrace();
        }
    });
}