package lis0924; import java.util.HashMap; import java.util.Iterator; import java.util.Map; import java.util.TreeMap; public class Text04 { public static void main(String[] args) { //map Map<String, String> m1=new HashMap<>(); //添加数据 //Key不能重复 //value可以重复 m1.put("0531", "济南"); m1.put("0532", "青岛"); m1.put("0533", "淄博"); m1.put("0531", "章丘");//如果key重复,新的value覆盖旧的value m1.put("0530", "章丘"); //System.out.println(m1); //长度 System.out.println("size="+m1.size()); //获取数据 System.out.println("0531="+m1.get("0531")); System.out.println("0530="+m1.get("0530")); //移除 m1.remove("0530"); System.out.println("size="+m1.size()); System.out.println("0530="+m1.get("0530")); System.out.println("key是否存在="+m1.containsKey("0533")); System.out.println("value是否存在="+m1.containsValue("淄博")); //遍历 //通过遍历key的set集合,同时获取value System.out.println("foreach方式:"); for(String k:m1.keySet()) { System.out.println("key="+k+"value="+m1.get(k)); } System.out.println("TreeMap"); //TreeMap TreeMap<Integer, Person> tm=new TreeMap<>(); tm.put(100, new Person("x",20)); tm.put(103, new Person("A",20)); tm.put(110, new Person("B",20)); tm.put(10, new Person("B",20)); tm.put(210, new Person("B",20)); //遍历 for(Integer k:tm.keySet())//通过遍历key的set集合赋值给k,同时获取value { System.out.println("key="+k+"value="+tm.get(k));//通过读k,也就是读key来获取value } } }