第三篇 集合与容器(三)
package com.zzp.demo; import java.util.HashMap; import java.util.Map; /** * * 测试HashMap * @author java * */ public class TestMap { public static void main(String[] args) { Map<Integer,String> m1 = new HashMap<Integer,String>(); m1.put(1, "一"); m1.put(2, "二"); m1.put(3, "三"); System.out.println(m1.get(1)); System.out.println(m1.isEmpty()); System.out.println(m1.containsKey(1)); System.out.println(m1.containsValue("四")); System.out.println(m1.size()); System.out.println(m1.toString()); Map<Integer,String> m2 = new HashMap<>(); m2.put(4, "三"); m2.put(5, "五"); m1.putAll(m2); System.out.println(m1); m2.clear(); System.out.println(m2); } }
第一版
package com.zzp.demo; import java.util.HashMap; import java.util.Map; public class TestMap02 { public static void main(String[] args) { Employee e1 = new Employee(1001, "张三", 10000); Employee e2 = new Employee(1002, "李四", 12000); Employee e3 = new Employee(1003, "王五", 13000); Map<Integer,Employee> m = new HashMap<>(); m.put(1001, e1); m.put(1002, e2); m.put(1003, e3); System.out.println(m.get(1001).getEname()); } } class Employee{ private int id; private String ename; private double salary; public Employee(int id, String ename, double salary) { super(); this.id = id; this.ename = ename; this.salary = salary; } public Employee() { super(); } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getEname() { return ename; } public void setEname(String ename) { this.ename = ename; } public double getSalary() { return salary; } public void setSalary(double salary) { this.salary = salary; } }