HashSet을 사용한 클래스 중복 제외

Student Class

public class Student {
 private String name;
 private int age;
 
 public Student(String name, int age) {
  this.name = name;
  this.age = age;
 }
 
 public String getName() {
  return name;
 }

 public int getAge() {
  return age;
 }
//=================================================
//추가 HashSet에 키로 사용할 필드를 Override 한다.
 @Override
 public int hashCode() {
  return name.hashCode();
 }

 @Override
 public boolean equals(Object obj) {
     if(!(obj instanceof Student)) {
            return false;
     }
 
     Student s = (Student)obj;
 
     return name.equals(s.name);
 }
//=================================================
}

 

Main Class

import java.util.HashSet;

public class MainTest {
 private static HashSet hashset = new HashSet();
 public static void main(String[] args) {
  hashset.add(new Student("홍길동", 25));
  hashset.add(new Student("똘이장군", 12));
  hashset.add(new Student("일지매", 23));
  hashset.add(new Student("똘이장군", 15));
  
  System.out.println("Student Count : " + hashset.size());
  for (Student std : hashset) {
   System.out.println(std.getName());
  }  
 }
}

 

결과값

Student Count : 3 홍길동 일지매 똘이장군

 

설명