Question

我是Java的新手，遇到了非常烦人的情况，三天后我甚至无法弄明白。我先发布我的代码。

import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Vector;

import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.table.DefaultTableModel;

public class StudentInfo extends JFrame {

ArrayList<Student> lstStudent = new ArrayList<Student>();

private JTable table = null;
private JButton btnAdd = null;

public StudentInfo() {
    table = new JTable();
    btnAdd = new JButton("Add");
    this.getContentPane().add(new JScrollPane(table), BorderLayout.CENTER);
    this.getContentPane().add(btnAdd, BorderLayout.SOUTH);
    this.setSize(600, 400);
    this.setVisible(true);
    this.setDefaultCloseOperation(EXIT_ON_CLOSE);

    updateTable();

    btnAdd.addActionListener(event -> {
        addStudent();
    });
}

public void addStudent() {
    StudentDetailDialog dialog = new StudentDetailDialog();
    Student student = new Student();
    student = dialog.dialog2Student();
    updateTable();
}

public void updateTable() {
    if(lstStudent.size() > 0) {
        Vector<Vector<Object>> tableData = new Vector<>();
        for(Student tempStudent : lstStudent) {
            Vector<Object> rowData = new Vector<>();
            rowData.add(tempStudent.getGiven());
            rowData.add(tempStudent.getLast());
            rowData.add(tempStudent.getGender());
            rowData.add(tempStudent.getAge());
            tableData.add(rowData);
        }

        Vector<String> colLabel = new Vector<>();
        colLabel.addAll(Arrays.<String> asList("Given Name", "Last Name", "Gender", "Age"));
        table.setModel(new DefaultTableModel(tableData, colLabel));
    }
    else {
        table.setModel(new DefaultTableModel(new Vector<>(), new Vector<>()));
    }
}

public static void main(String[] args) {
    SwingUtilities.invokeLater(() -> {
        new StudentInfo();
    });
}
}

class StudentDetailDialog extends JDialog {

private JLabel lblGiven = null;
private JTextField txtGiven = null;
private JLabel lblLast = null;
private JTextField txtLast = null;
private JLabel lblGender = null;
private JTextField txtGender = null;
private JLabel lblAge = null;
private JTextField txtAge = null;

private JButton btnOK = null;
private JButton btnCancel = null;

public StudentDetailDialog() {
    JPanel pnlCenter = new JPanel(new GridLayout(4, 2));
    lblGiven = new JLabel("Given Name:");
    txtGiven = new JTextField(10);
    lblLast = new JLabel("Last Name:");
    txtLast = new JTextField(10);
    lblGender = new JLabel("Gender:");
    txtGender = new JTextField(10);
    lblAge = new JLabel("Age:");
    txtAge = new JTextField(10);
    pnlCenter.add(lblGiven);
    pnlCenter.add(txtGiven);
    pnlCenter.add(lblLast);
    pnlCenter.add(txtLast);
    pnlCenter.add(lblGender);
    pnlCenter.add(txtGender);
    pnlCenter.add(lblAge);
    pnlCenter.add(txtAge);

    JPanel pnlSouth = new JPanel();
    btnOK = new JButton("OK");
    btnCancel = new JButton("Cancel");
    pnlSouth.add(btnOK);
    pnlSouth.add(btnCancel);

    this.add(pnlCenter, BorderLayout.CENTER);
    this.add(pnlSouth, BorderLayout.SOUTH);
    this.setSize(250, 200);
    this.setVisible(true);
    this.setDefaultCloseOperation(DISPOSE_ON_CLOSE);

    btnOK.addActionListener(event -> {
        dispose();
    });

    btnCancel.addActionListener(event -> {
        dispose();
    });
}

public Student dialog2Student() {
    Student student = new Student();
    student.setGiven(txtGiven.getText());
    student.setLast(txtLast.getText());
    student.setGender(txtGender.getText());
    student.setAge(Integer.valueOf(txtAge.getText()));
    return student;
}
}

class Student {
private String givenName = null;
private String lastName = null;
private String gender = null;
private int age = 0;

public void setGiven(String givenName) {
    this.givenName = givenName;
}

public String getGiven() {
    return givenName;
}

public void setLast(String lastName) {
    this.lastName = lastName;
}

public String getLast() {
    return lastName;
}

public void setGender(String gender) {
    this.gender = gender;
}

public String getGender() {
    return gender;
}

public void setAge(int age) {
    this.age = age;
}

public int getAge() {
    return age;
}
}

我想要做的是创建一个表并添加一些学生。但是在点击“添加”按钮后，会立即抛出一些错误，我甚至没有时间输入一个单词。我该怎么做才能搞清楚？错误信息附在下面。

Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: ""
at java.lang.NumberFormatException.forInputString(Unknown Source)
at java.lang.Integer.parseInt(Unknown Source)
at java.lang.Integer.valueOf(Unknown Source)
at class_demo.StudentDetailDialog.dialog2Student(StudentInfo.java:137)
at class_demo.StudentInfo.addStudent(StudentInfo.java:46)
at class_demo.StudentInfo.lambda$0(StudentInfo.java:39)
at class_demo.StudentInfo$$Lambda$27/32103433.actionPerformed(Unknown Source)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$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)

希望你们都明白我在说什么，因为我不是母语人士。无论如何，谢谢你们！

Answer 1

正如我的评论中所述，您的异常消息正在告诉您究竟出了什么问题 - 您正在尝试将空字符串""解析为数字，以及它出现的行：{{1 }}

问题包括

您的JDialog是非模态的，因此在用户有机会与对话框交互之前，会调用从对话框中提取数据的代码。
通过调用JDialog构造函数中的相应超级构造函数（使用ModalityType参数的构造函数）来创建对话框模态来解决此问题。
不要在构造函数中设置对话框，因为这会冻结student.setAge(Integer.valueOf(txtAge.getText()));调用下面的所有构造函数代码，导致程序无效。
而是在完全构建之后，在对话框中显示调用代码调用集。

您的对话框的btnOK和btnCancel ActionListeners是相同的，因此您的程序无法知道用户按哪个按钮。您可以通过为对话框提供某种类型的状态变量，并在调用dispose之前从这些ActionListener中设置它来解决此问题。

Answer 2

在输入所有细节之前，JDialog不会停止执行流程。

作为一种简单的解决方法，您可能希望将StudentDetailDialog设为JPanel，然后将其包裹在JOptionPane周围。

public void addStudent() {
    StudentDetailDialog dialog = new StudentDetailDialog();
    int result = JOptionPane.showConfirmDialog(null, dialog, "Student Details", JOptionPane.OK_CANCEL_OPTION);
    if (result == JOptionPane.OK_OPTION) {
        Student student = dialog.dialog2Student();
        updateTable();
    }
}

然后将StudentDetailDialog更改为JPanel。

class StudentDetailDialog extends JPanel {
    // Remove the Add and Cancel buttons since it would be part of JOptionPane.
}

单击确定按钮后如何获取输入？

2 个答案: