http://commons.apache.org/lang/api/org/apache/commons/lang3/builder/HashCodeBuilder.html
public class Person {
String name;
int age;
boolean smoker;
...
public int hashCode() {
// you pick a hard-coded, randomly chosen, non-zero, odd number
// ideally different for each class
return new HashCodeBuilder(17, 37).
append(name).
append(age).
append(smoker).
toHashCode();
}
}
객체의 equals, hashCode를 override해서 구현시에 hashcode를 만들어주는 메서드
