哈希小demo hashCode取模

package demo;import java.util.ArrayList;import java.util.List;class Person {private String username;private int age;public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public Person(String username, int age) {super();this.username = username;this.age = age;}@Overridepublic String toString() {return "Person [username=" + username + ", age=" + age + "]";}}public class Test {public static void printList(List list) {for(int i=0;i<list.size();i++) {System.out.println(list.get(i));}System.out.println("----------------------------------");}public static void main(String[] args) {int partition = 3;Person p1 = new Person("a",12);Person p2 = new Person("b",13);Person p3 = new Person("c",14);Person p4 = new Person("d",15);Person p5 = new Person("e",16);Person p[] = new Person[]{p1,p2,p3,p4,p5};List list0 = new ArrayList();List list1 = new ArrayList();List list2 = new ArrayList();for(int i=0;i<p.length;i++) {Person pi = p[i];int hash = pi.hashCode();System.out.println(hash);if(hash%partition==0) {list0.add(pi);}if(hash%partition==1) {list1.add(pi);}if(hash%partition==2) {list2.add(pi);}}printList(list0);printList(list1);printList(list2);}}

运行结果

638559109128716090417105372976367682901253637029Person [username=c, age=14]----------------------------------Person [username=a, age=12]----------------------------------Person [username=b, age=13]Person [username=d, age=15]Person [username=e, age=16]----------------------------------