1_intellij_equals.java

@Override
public boolean equals(Object o) {
  if (this == o) {
    return true;
  }
  if (!(o instanceof Student)) {
    return false;
  }
  Student student = (Student) o;
  return Objects.equals(getId(), student.getId()); // Java7+ 부터 사용할 수 있는 `Objects.equals`를 사용해봤다.
}

2_overideEquals.java

package io.github.leoheo.equals;

public class Main {

  public static void main(String[] args) {
    Student leo1 = new Student(1L, "Leo");
    Student leo2 = new Student(1L, "Leo");

    System.out.println("leo1 hashcode => " + leo1.hashCode());         // 1625635731
    System.out.println("leo2 hashcode => " + leo2.hashCode());        // 1580066828
    System.out.println("leo1.equals(leo2) => " + leo1.equals(leo2));  // true
  }
}