思路
直接根据月份做索引，然后根据日期边界判断是本月的星座还是上月的。
算法
private static String getAstro(int month, int day) {
String[] starArr = {"魔羯座","水瓶座", "双鱼座", "牡羊座",
"金牛座", "双子座", "巨蟹座", "狮子座", "处女座", "天秤座", "天蝎座", "射手座" };
int[] DayArr = {22, 20, 19, 21, 21, 21, 22, 23, 23, 23, 23, 22}; // 两个星座分割日
int index = month;
// 所查询日期在分割日之前，索引-1，否则不变
if (day < DayArr[month - 1]) {
index = index - 1;
}
// 返回索引指向的星座string
return starArr[index];
}
最终的效果图
初始图：
选择图：
判断星座
Java代码
package com.test0803; import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
/*
*
* */
class MyFrameee extends JFrame implements ItemListener { private JComboBox day = new JComboBox(), month = new JComboBox();
private JLabel tip = new JLabel("请选择日期");
public static final String[] starArr = {"魔羯座","水瓶座", "双鱼座", "牡羊座",
"金牛座", "双子座", "巨蟹座", "狮子座", "处女座", "天秤座", "天蝎座", "射手座" };
public static final int[] DayArr = {22, 20, 19, 21, 21, 21, 22, 23, 23, 23, 23, 22}; MyFrameee() {
super("星座计算");
for (int i = 1; i <= 12; i++) {
//void addItem(Object anObject) 为项列表添加项。
month.addItem(String.valueOf(i));
}
for (int i = 1; i <= 31; i++) {
day.addItem(String.valueOf(i));
}
//setForeground:设置此组件的前景色。
tip.setForeground(Color.blue); Container con = getContentPane();
con.setLayout(new FlowLayout());
con.add(month);
con.add(new JLabel("月-"));
con.add(day);
con.add(new JLabel("日"));
con.add(tip);
day.addItemListener(this);
month.addItemListener(this);
setSize(280, 100);
setLocation(400, 300);
setVisible(true);
setResizable(false);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
} public static String getConstellation(Calendar time) {
int month = time.get(Calendar.MONTH);
int day = time.get(Calendar.DAY_OF_MONTH);
if (day < DayArr[month]) {
month = month - 1;
}
if (month >= 0) {
return starArr[month];
}
return starArr[0];
} public void itemStateChanged(ItemEvent e) {
Calendar date = Calendar.getInstance();
date.set(2010, Integer.parseInt((String) month.getSelectedItem()),
Integer.parseInt((String) day.getSelectedItem()));
tip.setText(getConstellation(date));
}
} public class Test_Star2 {
public static void main(String[] args) {
new MyFrameee();
}
}
不足之处
为了方便，没有确定特殊月份的日期数量，都是按照31天处理的。