testhashset.java

自己做的一个QQ聊天系统

package test.colletion;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
public class TestHashSet {

	/**
	 * @param args
	 */
	@SuppressWarnings("unchecked")
	public static void main(String[] args) {
		// TODO Auto-generated method stub
        Set set = new HashSet();
        set.add("tarena");
        set.add("beijing");
        set.add("china");
       // System.out.println("集合大小:" + set.size());
        //Iterator it = set.iterator();
       // while (it.hasNext()){
        //	System.out.println(it.next());
       // }//迭代器
        set.clear();//请空
        set.add(new Student("zhangsan",21));
        set.add(new Student("lisi",22));
        set.add(new Student("zhangsan",21));
        set.add(new Student("wangwu",20));
        set.add(new Student("zhaoliu",25));
        set.add(new Student("zhangsan",21));
        System.out.println("集合大小:" + set.size()); //元素相同显示几?
        Iterator it = set.iterator();
        while (it.hasNext()){
        	System.out.println(it.next());
        }
	}

}
class Student{
	String name;
	int age;
	public Student(String name,int age){
		this.age = age;
		this.name = name;
	}
	@Override
	public int hashCode(){
		//return super.hashCode()
		System.out.println("equals()");
		return name.hashCode() + age;
	}
	@Override
	public boolean equals(Object obj){
		if(obj == null) return false;
		if(this==obj) return true;
		if(!(obj instanceof Student)) return false;
		Student stu = (Student) obj;
		if(this.name.equals(stu.name)&& this.age==stu.age)
			return true;
		return false;
		//return super.equals(obj);
	}
	@Override
	public String toString(){
		return name + "," + age;
	}
}//无序不可重复