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];

    }

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