Java如何使用Set接口存储没有重复元素的数组

 package 集合类;
 import java.util.HashSet;
 import java.util.Iterator;
 public class Set {
     public static void main(String[] args) {
         HashSet set=new HashSet();
         set.add("hello");
         set.add("world");
         set.add("abc");
         set.add("hello");
         Iterator it=set.iterator();
         while(it.hasNext()){
             Object obj=it.next();
             System.out.print(obj+ " ");
         }
     }
 }

 package 集合类;
 import java.util.HashSet;
 class Student{
     String id;
     String name;
     public Student(String id,String name){
         this.id=id;
         this.name=name;
     }
     public String toString(){
         String s = id + ":" + name;
         return s;
     }
 }
 public class Set1 {
     public static void main(String[] args) {
         HashSet hs=new HashSet();
         Student stu1=new Student("1","hello");
         Student stu2=new Student("2","world");
         Student stu3=new Student("1","hello");
         hs.add(stu1);
         hs.add(stu2);
         hs.add(stu3);
         System.out.println(hs);
     }
 }

package API;
 import java.util.HashSet;
 class Student{
     private String id;
     private String name;
     public Student(String id,String name){
         this.id=id;
         this.name=name;
     }
     //重写toString方法
     public String toString(){
         return id+ ":"+name;
     }
     //重写hashCode方法
     public int hashCode(){
         //返回id属性的哈希值
         return id.hashCode();
     }
     public boolean equals(Object obj){
         //判断是否是同一个对象
         if(this==obj){
             return true;
         }
         //判断对象是Student类型
         if(!(obj instanceof Student)){
             return false;
         }
         //将对象强转为Student类型
         Student stu=(Student)  obj;
         //判断id是否相同
         boolean b=this.id.equals(stu.id);
         return b;
     }
 }
 public class Set2 {
     public static void main(String[] args) {
         HashSet hs=new HashSet();
         Student stu1=new Student("1","hello");
         Student stu2=new Student("2","world");
         Student stu3=new Student("1","hello");
         hs.add(stu1);
         hs.add(stu2);
         hs.add(stu3);
         System.out.println(hs);
     }
 }