自定義物件排序
阿新 • • 發佈:2019-02-13
import java.util.HashMap; public class Demo { public static void main(String[] args) { HashMap<Student, String> hm = new HashMap<Student, String>(); hm.put(new Student("張三", 30), "基礎班"); hm.put(new Student("張三", 30), "基礎班"); hm.put(new Student("張三", 20), "基礎班"); hm.put(new Student("李四", 20), "基礎班"); System.out.println(hm.toString()); } } class Student implements Comparable<Student> { String name; int age; public Student(String name, int age) { super(); this.name = name; this.age = age; } @Override public String toString() { return name + ":" + age; } @Override public int compareTo(Student o) { int num = this.name.compareTo(o.name); return num == 0 ? new Integer(this.age) .compareTo(new Integer( o.age)) : num; } }