自动填充系列组合框 - Java

Posted 2023-02-24

【中文标题】自动填充系列组合框 - Java

【英文标题】：AutoFill series of ComboBoxes - Java

【发布时间】：2013-03-28 19:08:22

【问题描述】：

我正在编写一个简单的程序；这个程序的一部分是一系列组合框，我在其中输入了月份（alpha）、天（数字）和年（数字）的字符串。我想以某种方式让 Java 以月、日和年的形式提取日期，然后根据系统时钟用正确的日期自动填充这些组合框。

这是我的一些代码：

public static final String[] MONTHS = "January", "February", "March", "April", "May", "June",
                                       "July", "August", "September", "October", "November",
                                       "December";
public static final 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";
public static final String[] YEARS = "2015", "2014", "2013", "2012", "2011", "2010";

Note to FORUMS: THIS ISN'T ALL THE CODE. I'VE JUST PROVIDED INFORMATION NECESSARY FOR THE QUESTION.

JLabel start = new JLabel("Start Date:");
if (shouldWeightX) 
c.weightx = .5;

c.fill = GridBagConstraints.HORIZONTAL;
c.gridx = 0;
c.gridy = 1;
c.gridwidth = 1;
pane.add(start, c);

JComboBox MonthLong = new JComboBox();
if (shouldWeightX) 
    c.weightx = 0;
    
c.fill = GridBagConstraints.HORIZONTAL;
c.gridx = 1;
c.gridy = 1;
c.gridwidth = 1;
for(int i=0; i<MONTHS.length;i++) 
        MonthLong.addItem(MONTHS[i]);
    
pane.add(MonthLong, c);

JComboBox DayLong = new JComboBox();
if (shouldWeightX) 
    c.weightx = 1.0;
    
c.fill = GridBagConstraints.HORIZONTAL;
c.gridx = 2;
c.gridy = 1;
c.gridwidth = 1;
for(int i=0; i<DAYS.length;i++) 
    DayLong.addItem(DAYS[i]);

pane.add(DayLong, c);

JComboBox YearLong = new JComboBox();
if (shouldWeightX) 
    c.weightx = 1.0;
    
c.fill = GridBagConstraints.HORIZONTAL;
c.gridx = 3;
c.gridy = 1;
c.gridwidth = 1;
for(int i=0; i<YEARS.length;i++) 
    YearLong.addItem(YEARS[i]);

YearLong.setSelectedItem("2013");
pane.add(YearLong, c);

提前致谢。

【参考方案1】：

您应该使用 java.util.Calendar 类获取当前时间部分。

Calendar now = Calendar.getInstance();
// months start with 0 
System.out.println("Year is: " + now.get(Calendar.YEAR));   
System.out.println("Month is: " + (now.get(Calendar.MONTH) + 1));
System.out.println("Date is: " + now.get(Calendar.DATE));

然后您可以在初始化步骤中在您的组合框上设置SelectedIndex。

还请记住，您不必使用 for 循环将这些字符串添加到组合框。试试看吧。

JComboBox<String> MonthLong = new JComboBox<String>(MONTHS);

【参考方案2】：

我没有测试这段代码。

    Calendar now = Calendar.getInstance();
    int month = now.get(Calendar.MONTH);
    int day = now.get(Calendar.DAY_OF_MONTH);
    int year = now.get(Calendar.YEAR);

    MonthLong.setSelectedIndex(month);
    DayLong.setSelectedItem(Integer.toString(day));
    YearLong.setSelectedItem(Integer.toString(year));

在 Java 中，变量通常以小写字母开头。

【讨论】：

这成功了！非常感谢你。另外，我知道变量的小写字母，我正在为其他人编辑一些代码，但在这个问题中我说它是“我的”。哎呀！再次感谢。