789

Posted 2020-11-19 ftl1012

1. map
1.1. map中的方法
wpsB935.tmp

1.2. Map.Entry
对于集合来讲，就是把kye-value的数据保存在了Map.Entry的实例之后，再在Map集合中插入了一个Map.Entry的实例化对象

Map.Entry一般用于输出集合

wpsB946.tmpwpsB947.tmp

wpsB948.tmp

1.3. Map接口的常用子类
wpsB959.tmp

1.4. HashTable和HashMap区别
wpsB95A.tmp

1.5. Map的标准输出(2个)
方案一：

wpsB95B.tmp

方案二：

wpsB96B.tmp=package com.ftl;

import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.TreeMap;

public class map {
    public static void main(String[] args){
       
        Map<String,String>map = new TreeMap<>();
        map.put("Hello", "world");
        map.put("Hello1", "world1");
        map.put("Hello2", "world2");
        map.put("Hello3", "world3");
        String str = map.get("Hello");
        Set<String> set = map.keySet();
        Collection<String> values = map.values();
        Iterator<String> iterator = set.iterator();
        Iterator<String> iter = values.iterator();
       
        System.out.println(" foreach方法：");
        for (String s : values) {
            System.out.print(s+"、");
        }
       
        System.out.println(" Iterator方法：");
        while(iterator.hasNext()){
            System.out.print(iterator.next()+"、");
        }
       
        System.out.println(" Map的标准输出_1(Map.entrySet)：");
        Set<Entry<String,String>> entrySet = map.entrySet();
        Iterator<Map.Entry<String, String>> it = entrySet.iterator();
        while(it.hasNext()){
            Map.Entry<String, String> next = it.next();
            System.out.print(next.getKey()+"-->: "+next.getValue()+" ");
        }
        System.out.println(" Map的标准输出_2(Foreach)：");
        for (Map.Entry<String, String> entry : entrySet) {
            System.out.print(entry.getKey()+"-->: "+entry.getValue()+" ");
        }
        System.out.println("Map.entrySet()大小："+map.entrySet().size());
    }

}

 

1.6. 人员配置
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.TreeMap;

public class map {
    public static void main(String[] args){
       
        Map<String,String>map = new TreeMap<>();
        map.put("Hello", "world");
        map.put("Hello1", "world1");
        map.put("Hello2", "world2");
        map.put("Hello3", "world3");
        String str = map.get("Hello");
        Set<String> set = map.keySet();
        Collection<String> values = map.values();
        Iterator<String> iterator = set.iterator();
        Iterator<String> iter = values.iterator();
       
        System.out.println(" foreach方法：");
        for (String s : values) {
            System.out.print(s+"、");
        }
       
        System.out.println(" Iterator方法：");
        while(iterator.hasNext()){
            System.out.print(iterator.next()+"、");
        }
       
        System.out.println(" Map的标准输出_1(Map.entrySet)：");
        Set<Entry<String,String>> entrySet = map.entrySet();
        Iterator<Map.Entry<String, String>> it = entrySet.iterator();
        while(it.hasNext()){
            Map.Entry<String, String> next = it.next();
            System.out.print(next.getKey()+"-->: "+next.getValue()+" ");
        }
        System.out.println(" Map的标准输出_2(Foreach)：");
        for (Map.Entry<String, String> entry : entrySet) {
            System.out.print(entry.getKey()+"-->: "+entry.getValue()+" ");
        }
        System.out.println("Map.entrySet()大小："+map.entrySet().size());
    }

}