HashSet的size问题

//打印什么？为什么？

public class TestSet {
	public static void main(String[] args) {
		Set<Short> s=new HashSet<Short>();
		for(short i=0;i<10;i++){
			s.add(i);
			s.remove(i-1);
		}
		System.out.println("size of s:"+s.size());
	}
}

评论

1 楼 lclcr 2010-05-21  

按照你上面的代码我写了两个，希望你能够对比一下，找到原因，具体不说了，看代码吧：

import java.util.HashSet;

//第一个：关于Integer的

import java.util.Set;

public class TestSetInteger {  
    public static void main(String[] args) {  
        Set<Integer> s=new HashSet<Integer>();  
        for(int i=0;i<10;i++){  
        System.out.println("int(i) = "+(int)i);
        System.out.println("添加前 i = "+i);
            boolean mark = s.add(i);
            if(mark){
            System.out.println("添加："+i+" 成功");
            }else{
            System.out.println("添加："+i+" 失败");
            }
            System.out.println("size of s:"+s.size());
            System.out.println("添加后i = "+i);
            int k = i-1;
            boolean flag = s.remove(k);
            System.out.println("删除 k ="+k);
            if(flag){
            System.out.println("删除："+k+" 成功");
            }else{
            System.out.println("删除："+k+" 失败");
            }
            System.out.println("size of s:"+s.size());
        }  
    }  
} 

import java.util.HashSet;

//第二个：关于Short的

import java.util.Set;

public class TestSetShort {  
    public static void main(String[] args) {  
        Set<Short> s=new HashSet<Short>();  
        for(short i=0;i<10;i++){  
        System.out.println("int(i) = "+(int)i);
        System.out.println("添加前 i = "+i);
            boolean mark = s.add(i);
            if(mark){
            System.out.println("添加："+i+" 成功");
            }else{
            System.out.println("添加："+i+" 失败");
            }
            System.out.println("size of s:"+s.size());
            System.out.println("添加后i = "+i);
            [color=red]short k = (short)(i-1);  //注意这里
            boolean flag = s.remove(k);
            System.out.println("删除 k ="+k);
            if(flag){
            System.out.println("删除："+k+" 成功");
            }else{
            System.out.println("删除："+k+" 失败");
            }
            System.out.println("size of s:"+s.size());
        }  
    }  
}  [/color]