stringcomparator.java

java阿里巴巴代码

/**
 * StringComparator.java
 * 
 * This class is used along with TreeMap
 * When put a key into a TreeMap, TreeMap will replace the old having the same key with the new 
 * but when you use this class, you can control this case
 * though the key is the same, the Comparator will return false if you set the flag 'takeEqual=true'
 */

package tools.util;

import java.util.Comparator;
import java.util.Iterator;
import java.util.TreeMap;

public class StringComparator implements Comparator
{
	private int takeEqual = 0;
	private boolean desc	= false;

	/**
	 * IntegerComparator, Constructor
	 * @param boolean takeEqual, if true, return 1 when equal, 
	 */
	public StringComparator(boolean takeEqual)
	{
		this.takeEqual = (takeEqual==true) ? 1 : 0;
	}

	/**
	 * StringComparator, Constructor
	 * @param boolean takeEqual, if true, return 1 when equal, 
	 * @param boolean desc
	 */
	public StringComparator(boolean takeEqual, boolean desc)
	{
		this.takeEqual = (takeEqual==true) ? 1 : 0;
		this.desc		= desc;
	}

	/**
	 * compare, compare 2 objects
	 * @param Object o1 
	 * @param Object o2
	 * @return int, 1 ==> o1 > o2, -1 ==> o1 < o2, 0 ==> o1 = o2
	 */
	public int compare(Object o1, Object o2)
	{
		String str1 = ((String)o1).toUpperCase();
		String str2 = ((String)o2).toUpperCase();

		if (!desc)		// ASC
		{
			if(str1.compareTo(str2) < 0) return -1;
			if(str1.compareTo(str2) > 0) return 1;
		}
		else			// DESC
		{
			if(str1.compareTo(str2) < 0) return 1;
			if(str1.compareTo(str2) > 0) return -1;
		}

		return takeEqual;
	}
	public boolean equals(Object obj)
	{
		return false;
	}
	static public void main(String[] args)
	{
		test(true);
		test(false);
	}
	static private void test(boolean flag)
	{
		System.out.println("\nflag: " + flag);
		TreeMap map = new TreeMap(new StringComparator(flag));
		String str1 = "string #1";
		String str2 = "string #2";
		String str3 = "string #2";
		String str4 = "string #4";
		map.put(str1, str1);
		map.put(str2, str2);
		map.put(str3, str3);
		map.put(str4, str4);
		
		for(Iterator it=map.values().iterator(); it.hasNext();)
		{
			String str = (String)it.next();
			System.out.println("str: " + str);
		}
	}
}