CountedString.java

package chapter17.nine.three;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * ¼ÆËãhashCode
 * @author admin
 *
 */
public class CountedString {

	private static List<String> created=new ArrayList<String>();
	private String s;
	private int id=0;
	public CountedString(String str) {
		// TODO Auto-generated constructor stub
		s=str;
		created.add(s);
		for(String s2:created){
			if(s2.equals(s)){
				id++;
			}
		}
	}
	@Override
	public String toString() {
		// TODO Auto-generated method stub
		return "String:"+s+"id:"+id+"hashCode():"+hashCode();
	}
	
	@Override
	public int hashCode() {
		// TODO Auto-generated method stub
		int result=17;
		result=37*result+s.hashCode();
		result=37*result+id;
		return result;
	}
	
	public boolean equals(Object obj){
		return obj instanceof CountedString && s.equals(((CountedString)obj).s) &&
				id==((CountedString)obj).id;
	}
	
	public static void main(String[] args) {
		Map<CountedString, Integer> map=new HashMap<CountedString, Integer>();
		CountedString[] cs=new CountedString[5];
		for (int i = 0; i < cs.length; i++) {
			cs[i]=new CountedString("hi");
			map.put(cs[i], i);
		}
		System.out.println(map);
		for(CountedString cstring:cs){
			System.out.println("Looking up"+cstring);
			System.out.println(map.get(cstring));
		}
	}
}