java中关于Map的三种遍历方法详解
发布时间:2020-12-14 14:25:50 所属栏目:Java 来源:网络整理
导读:map的三种遍历方法! 集合的一个很重要的操作---遍历,学习了三种遍历方法,三种方法各有优缺点~~ 复制代码 代码如下: /* * To change this template,choose Tools | Templates * and open the template in the editor. */ package cn.tsp2c.liubao; import
map的三种遍历方法! 集合的一个很重要的操作---遍历,学习了三种遍历方法,三种方法各有优缺点~~ 复制代码 代码如下: /* * To change this template,choose Tools | Templates * and open the template in the editor. */ package cn.tsp2c.liubao; import java.util.Collection; import java.util.HashMap; import java.util.Iterator; import java.util.Map; import java.util.Set; import java.util.TreeMap; /** * * @author Administrator */ public class TestMap { public static void main(String[] args) { Map<String,Student> map = new HashMap<String,Student>(); Student s1 = new Student("宋江","1001",38); Student s2 = new Student("卢俊义","1002",35); Student s3 = new Student("吴用","1003",34); map.put("1001",s1); map.put("1002",s2); map.put("1003",s3); Map<String,Student> subMap = new HashMap<String,Student>(); subMap.put("1008",new Student("tom","1008",12)); subMap.put("1009",new Student("jerry","1009",10)); map.putAll(subMap); work(map); workByKeySet(map); workByEntry(map); } //最常规的一种遍历方法,最常规就是最常用的,虽然不复杂,但很重要,这是我们最熟悉的,就不多说了!! public static void work(Map<String,Student> map) { Collection<Student> c = map.values(); Iterator it = c.iterator(); for (; it.hasNext();) { System.out.println(it.next()); } } //利用keyset进行遍历,它的优点在于可以根据你所想要的key值得到你想要的 values,更具灵活性!! public static void workByKeySet(Map<String,Student> map) { Set<String> key = map.keySet(); for (Iterator it = key.iterator(); it.hasNext();) { String s = (String) it.next(); System.out.println(map.get(s)); } } //比较复杂的一种遍历在这里,呵呵~~他很暴力哦,它的灵活性太强了,想得到什么就能得到什么~~ public static void workByEntry(Map<String,Student> map) { Set<Map.Entry<String,Student>> set = map.entrySet(); for (Iterator<Map.Entry<String,Student>> it = set.iterator(); it.hasNext();) { Map.Entry<String,Student> entry = (Map.Entry<String,Student>) it.next(); System.out.println(entry.getKey() + "--->" + entry.getValue()); } } } class Student { private String name; private String id; private int age; public Student(String name,String id,int age) { this.name = name; this.id = id; this.age = age; } @Override public String toString() { return "Student{" + "name=" + name + "id=" + id + "age=" + age + '}'; } } (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |