package cn.cqu.huang;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
public class SetDemo {
	public static void main(String[] args) {
		String[] a = {"ZhangSan","LiSi","WangWu","ZhaoLiu","QianQi"};//所有考生
		String[] b = {"ZhangSan,语文，80",
					  "ZhangSan,英语，89",
					  "LiSi,数学,69",
					  "LiSi,英语,99",
					  "ZhaoLiu,数学,78"};//已经参加考试的学生成绩单
		
		//求哪些考生缺考
		
		Set<String> sa = new HashSet<String>();
		for(int i=0;i<a.length;i++){
			sa.add(a[i]);
		}
		
		Set<String> sb = new HashSet<String>();
		for(int i=0;i<b.length;i++){
			sb.add(b[i].split(",")[0]);
		}
		
		sa.removeAll(sb);  //集合的差集
		
		//遍历sa中剩下的元素，也即未参加考试的考生
		Iterator<String> it = sa.iterator();
		while(it.hasNext()){
			System.out.println(it.next());
		}
	}
}