我正在为学校创建一个费用报告计划，我们只能使用书中的内容，所以我不得不妥协。我用comboBoxes制作的日历选择器。我希望日期选项能够随着选择的月份动态变化。由于某种原因，它只适用于returnPanel而不是departPanel。
是的，导入了许多不必要的东西，但我只是保留一个列表，因为事情不断变化。
import java.awt.BorderLayout;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.List;
import java.io.File;
import java.io.FileNotFoundException;
import java.text.DecimalFormat;
import java.util.Scanner;
import java.util.ArrayList;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class TestWindow extends JFrame {
private JPanel departPanel;
private JPanel returnPanel;
private JComboBox monthsBox;
private JComboBox daysBox;
private JComboBox yearsBox;
private JComboBox departTimeBox;
private JComboBox returnTimeBox;
private JLabel calendarLabel;
private String[] months = {"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul",
"Aug", "Sept", "Oct", "Nov", "Dec" };
private String[] days = {"1", "2", "3", "4", "5", "6", "7", "8",
"9", "10", "11", "12", "13", "14", "15", "16",
"17", "18", "19", "20", "21", "22", "23", "24",
"25", "26", "27", "28", "29", "30", "31"};
private String[] years = {"2015"};
private String[] time = {"1:00AM", "2:00AM", "3:00AM", "4:00AM", "5:00AM",
"6:00AM", "7:00AM", "8:00AM", "9:00AM", "10:00AM",
"11:00AM", "12:00PM", "1:00PM", "2:00PM", "3:00PM",
"4:00PM", "5:00PM", "6:00PM", "7:00PM", "8:00PM",
"9:00PM", "10:00PM", "11:00PM", "12:00AM"};
public TestWindow() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new GridLayout(2,1));
buildDepartPanel();
buildReturnPanel();
add(departPanel);
add(returnPanel);
pack();
setVisible(true);
}
private void buildDepartPanel() {
departPanel = new JPanel();
monthsBox = new JComboBox(months);
daysBox = new JComboBox(days);
yearsBox = new JComboBox(years);
departTimeBox = new JComboBox(time);
JLabel departLabel = new JLabel ("Departure");
departPanel.add(departLabel);
departPanel.add(monthsBox);
departPanel.add(daysBox);
departPanel.add(yearsBox);
departPanel.add(departTimeBox);
monthsBox.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if(monthsBox.getSelectedItem().equals("Jan")
|| monthsBox.getSelectedItem().equals("Mar")
|| monthsBox.getSelectedItem().equals("May")
|| monthsBox.getSelectedItem().equals("Jul")
|| monthsBox.getSelectedItem().equals("Aug")
|| monthsBox.getSelectedItem().equals("Oct")
|| monthsBox.getSelectedItem().equals("Dec")) {
int items = daysBox.getItemCount();
if(items == 29) {
daysBox.addItem("30");
daysBox.addItem("31");
} else if(items == 30) {
daysBox.addItem("31");
}
} else if(monthsBox.getSelectedItem().equals("Apr")
|| monthsBox.getSelectedItem().equals("Jun")
|| monthsBox.getSelectedItem().equals("Sept")
|| monthsBox.getSelectedItem().equals("Nov")) {
int items = daysBox.getItemCount();
if(items == 29) {
daysBox.addItem("30");
} else if(items == 31) {
daysBox.removeItemAt(30);
}
} else if(monthsBox.getSelectedItem().equals("Feb")) {
int items = daysBox.getItemCount();
if(items == 31) {
daysBox.removeItemAt(30);
daysBox.removeItemAt(29);
} else if(items == 30) {
daysBox.removeItemAt(29);
}
}
}
});
}
private void buildReturnPanel() {
returnPanel = new JPanel();
monthsBox = new JComboBox(months);
daysBox = new JComboBox(days);
yearsBox = new JComboBox(years);
returnTimeBox = new JComboBox(time);
JLabel returnLabel = new JLabel ("Return");
returnPanel.add(returnLabel);
returnPanel.add(monthsBox);
returnPanel.add(daysBox);
returnPanel.add(yearsBox);
returnPanel.add(returnTimeBox);
monthsBox.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if(monthsBox.getSelectedItem().equals("Jan")
|| monthsBox.getSelectedItem().equals("Mar")
|| monthsBox.getSelectedItem().equals("May")
|| monthsBox.getSelectedItem().equals("Jul")
|| monthsBox.getSelectedItem().equals("Aug")
|| monthsBox.getSelectedItem().equals("Oct")
|| monthsBox.getSelectedItem().equals("Dec")) {
int items = daysBox.getItemCount();
if(items == 29) {
daysBox.addItem("30");
daysBox.addItem("31");
} else if(items == 30) {
daysBox.addItem("31");
}
} else if(monthsBox.getSelectedItem().equals("Apr")
|| monthsBox.getSelectedItem().equals("Jun")
|| monthsBox.getSelectedItem().equals("Sept")
|| monthsBox.getSelectedItem().equals("Nov")) {
int items = daysBox.getItemCount();
if(items == 29) {
daysBox.addItem("30");
} else if(items == 31) {
daysBox.removeItemAt(30);
}
} else if(monthsBox.getSelectedItem().equals("Feb")) {
int items = daysBox.getItemCount();
if(items == 31) {
daysBox.removeItemAt(30);
daysBox.removeItemAt(29);
} else if(items == 30) {
daysBox.removeItemAt(29);
}
}
}
});
}
public static void main(String[] args) {
new TestWindow();
}
}t
答案 0 :(得分：0)
实例变量（monthsBox，daysBox等等）维护对JComboBox的引用，在调用buildDepartPanel时创建，并再次在buildReturnPanel中创建。调用ActionListener时，它使用当前引用（在此上下文中是最后创建的引用 - 在buildReturnPanel中）。可以通过多种方式修复，例如为表示离开和返回面板的这些对象创建实例变量。鉴于两种构建方法之间发生的代码重复，您最好创建一个通用方法或类来合并重复的代码。例如：
public class DatePanel extend JPanel{
//instance variables here
public DatePanel(){
//construct UI
}
}
然后只需创建此类的实例并将其添加到您的UI
DatePanel returnPanel = new DatePanel();
add(returnPanel);
答案 1 :(得分：0)
您的组合框是字段，这意味着它们处于对象级别。每个TestWindow实例只有一个。当你调用buildReturnPanel（）方法时，它会覆盖你在buildDepartPanel（）方法中设置的值，所以当调用你的动作监听器时，它们只会看到返回的组合框。
理想情况下，因为您的离开和返回面板是相同的，我建议为UI项目设置一个单独的类并将其实例化两次。我不知道你的任务是否可行。如果你不能，那么你可以在方法中声明组合框为final：
final JComboBox monthsBox = new JComboBox(months);
...
使用final将让匿名的ActionListener类看到变量。