import java.util.Objects;
public class Character {
private String Name;
public Character(String name) {
Name = name;
}
public String getName() {
return Name;
}
public void setName(String name) {
Name = name;
}
public static void main(String[] args) {
Character character1 = new Character("Arnold");
System.out.println(character1.getName());
System.out.println(character1.hashCode());
Character character2 = new Character("Arnold");
System.out.println(character2.getName());
System.out.println(character2.hashCode());
System.out.println(character2.equals(character1));
}
}
import java.util.Date;
public class Student {
String surname;
String name;
String secondName;
Long birthday; // Long instead of long is used by Gson/Jackson json parsers and various orm databases
public Student(String surname, String name, String secondName, Date birthday ){
this.surname = surname;
this.name = name;
this.secondName = secondName;
this.birthday = birthday == null ? 0 : birthday.getTime();
}
//Java hashcode example
@Override
public int hashCode(){
//TODO: check for nulls
//return surname.hashCode() ^ name.hashCode() ^ secondName.hashCode() ^ (birthday.hashCode());
return (surname + name + secondName + birthday).hashCode();
}
@Override
public boolean equals(Object other_) {
Student other = (Student)other_;
return (surname == null || surname.equals(other.surname) )
&& (name == null || name.equals(other.name))
&& (secondName == null || secondName.equals(other.secondName))
&& (birthday == null || birthday.equals(other.birthday));
}
}
และ ชั้นเรียน หลักเพื่อสาธิตการทำงานของพวกเขา:
import java.util.Date;
import java.util.HashMap;
import java.util.Hashtable;
public class Main {
static HashMap<Student, Integer> cache = new HashMap<Student, Integer>(); // <person, targetPriority>
public static void main(String[] args) {
Student sarah1 = new Student("Sarah","Connor", "Jane", null);
Student sarah2 = new Student("Sarah","Connor", "Jane", new Date(1970, 01-1, 01));
Student sarah3 = new Student("Sarah","Connor", "Jane", new Date(1959, 02-1, 28)); // date not exists
Student john = new Student("John","Connor", "Kyle", new Date(1985, 02-1, 28)); // date not exists
Student johnny = new Student("John","Connor", "Kyle", new Date(1985, 02-1, 28)); // date not exists
System.out.println(john.hashCode());
System.out.println(johnny.hashCode());
System.out.println(sarah1.hashCode());
System.out.println();
cache.put(sarah1, 1);
cache.put(sarah2, 2);
cache.put(sarah3, 3);
System.out.println(new Date(sarah1.birthday));
System.out.println();
cache.put(john, 5);
System.out.println(cache.get(john));
System.out.println(cache.get(johnny));
cache.put(johnny, 7);
System.out.println(cache.get(john));
System.out.println(cache.get(johnny));
}
}
ในกรณีตัวอย่างของเรา เรามีโค้ดถัดไป:
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