Question

这个GUI程序的主要目的是让用户在第一个名字框中输入学生的名字，在姓氏框中输入相应的姓氏，然后点击保存。然后，点击保存会将名字和姓氏保存到各自的数组中。用户完成输入名称后，他们将点击排序。然后，这将按字母顺序对名称进行排序，然后重新绘制GUI以显示新排序的名称数组的结果。我的主要问题是当我输入一个名字时，我会得到一个错误的清单（见下文）。我也不知道如何重绘GUI以显示列表中的名称数组。任何帮助将不胜感激，谢谢！

这是我目前的代码。（变量名很长，但我讨厌变量名，然后忘记它们的用途。） import java.awt。*;

import javax.swing.*;

import java.awt.event.*;

import javax.swing.*;

public class main extends JFrame {

    JTextField studentNameInputFirst, studentNameInputLast, studentNamesEnetered;
    JButton nextName, sort;
    JLabel firstName, lastName;
    String disp = "";
    int totalNumberOfStudents = 0;
    String[] studentFirstNames = new String[totalNumberOfStudents];
    String[] studentLastNames = new String[totalNumberOfStudents];

    public main() {
        Container container = getContentPane();
        container.setLayout(new FlowLayout());

        studentNamesEnetered = new JTextField();
        studentNameInputFirst = new JTextField(15);
        studentNameInputLast = new JTextField(15);
        nextName = new JButton("Save");
        sort = new JButton("Sort");
        firstName = new JLabel("First Name: ");
        lastName = new JLabel("Last Name: ");

        container.add(firstName);
        container.add(studentNameInputFirst);
        container.add(lastName);
        container.add(studentNameInputLast);
        container.add(nextName);
        container.add(sort);

        nextName.addActionListener(new nextNameListener());
        sort.addActionListener(new sortListener());

        setSize(325, 120);
        setVisible(true);
    }

    private class nextNameListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            totalNumberOfStudents++;
            studentFirstNames[totalNumberOfStudents] = studentNameInputFirst.getText();
            studentLastNames[totalNumberOfStudents] = studentNameInputLast.getText();
            studentNameInputLast = null;
            studentNameInputFirst = null;
        }
    }
    private class sortListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {
        }
    }

    public static void main(String[] args) {
        main drawGui = new main();
        drawGui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}

以下是运行上述代码时出现的错误：

Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 1
    at main$nextNameListener.actionPerformed(main.java:48)
    at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
    at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
    at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
    at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
    at javax.swing.plaf.basic.BasicButtonListener.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$500(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)

编辑：使用提供的答案建议使用ArrayList而不是普通数组后，我不会再遇到错误。我对程序的命名进行了更改，以遵循Java命名约定和我自己理解程序的功能。在第13,14,45和46行进行了更改。感谢您的帮助！

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.ArrayList;
import javax.swing.*;

public class ClassNameSorting extends JFrame {

    JTextField studentNameInputFirst, studentNameInputLast, studentNamesEnetered;
    JButton nextName, sort;
    JLabel firstName, lastName;
    String disp = "";
    ArrayList<String> studentNameFirst = new ArrayList<String>();
    ArrayList<String> studentNameLast = new ArrayList<String>();


    public ClassNameSorting() {
        Container container = getContentPane();
        container.setLayout(new FlowLayout());

        studentNamesEnetered = new JTextField();
        studentNameInputFirst = new JTextField(15);
        studentNameInputLast = new JTextField(15);
        nextName = new JButton("Save");
        sort = new JButton("Sort");
        firstName = new JLabel("First Name: ");
        lastName = new JLabel("Last Name: ");

        container.add(firstName);
        container.add(studentNameInputFirst);
        container.add(lastName);
        container.add(studentNameInputLast);
        container.add(nextName);
        container.add(sort);

        nextName.addActionListener(new nextNameListener());
        sort.addActionListener(new sortListener());

        setSize(325, 120);
        setVisible(true);
    }

    private class nextNameListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            studentNameFirst.add(studentNameInputFirst.getText());
            studentNameLast.add(studentNameInputLast.getText());
            studentNameInputLast = null;
            studentNameInputFirst = null;
        }
    }
    private class sortListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {
        }
    }

    public static void main(String[] args) {
        ClassNameSorting drawGui = new ClassNameSorting();
        drawGui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}

Answer 1

int totalNumberOfStudents = 0;
String[] studentFirstNames = new String[totalNumberOfStudents];
String[] studentLastNames = new String[totalNumberOfStudents];

您的数组大小为0.您需要为数组分配当前要添加到数组中的条目数。

不要使用数组，因为你不知道它的大小。而是使用ArrayList。

JTextField和getActionCommand存储在用户扩展数组中

1 个答案: