Java学习---Map的学习

1. Map

1.1. map中的方法

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 

1.3. Map接口的常用子类

1.4. HashTable和HashMap区别

1.5. Map的标准输出(2个)

Map的方法使用集合

package com.ftl;

import java.util.*;


class Person implements Comparable<Person>
{
    private String name;
    private int age;
    public Person(String name, int age)
    {
        this.age = age;
        this.name = name;
    }
    @Override
    public String toString() {
        return "姓名：" + this.name + ", 年龄：" + this.age ;
    }
    public boolean equals(Object obj)
    {
        boolean flag = true;
        if ( this == obj)
        {
            return flag ;
        }
        if ( !(obj instanceof Person))
        {
            flag =  false;
        }
        Person p = (Person)obj;        
            if (this.name.equals(p.name)
                    && this.age == p.age)
            {
                return flag;
            }
            else
            {
                flag = false;
            }
        
        return flag;
    }
    
    public int hashCode()
    {
        return this.name.hashCode() * this.age;
    }
    
    @Override
    public int compareTo(Person per) {
        if ( this.age > per.age)
        {
            return 1;
        }
        else if (this.age < per.age)
        {
            return -1;
        }
        else
        {
            return this.name.compareTo(per.name);
        }
    }
    
}


public class HelloFtl {
    public static void main(String[] args) throws Exception {
        // TODO 自动生成的方法存根
        System.out.println("--------------------------------------");
            List<String> allList = null;
            Collection<String> col = null;
            allList = new ArrayList<String>();
            col = new ArrayList<String>();
            allList.add("Hello");
            allList.add("world");
            System.out.println(allList);
        System.out.println("--------------------------------------");
            col.add("HHH");
            col.add("FTL");
            col.add("WM");
            allList.addAll(allList.size(), col);
            System.out.println(allList);
//        System.out.println("--------------------------------------");
//            allList.remove(0);
//            System.out.println(allList);
//        System.out.println("--------------------------------------");
            allList.removeAll(col);
//            System.out.println(allList);
        System.out.println("--------------------------------------");
            for(int i = 0; i < allList.size(); i++)
            {
                System.out.print(allList.get(i) + "、");
            }
        System.out.println();
        System.out.println("--------------------------------------");
            for(int i = allList.size()-1; i >=0 ; i--)
            {
                System.out.print(allList.get(i) + "、");
            }
            System.out.println();
        System.out.println("--------------------------------------");
            Object[] obj = allList.toArray();
            for(int i = 0; i <obj.length; i++)
            {
                String temp = (String)obj[i];
                System.out.print(temp + "、");
            }
        System.out.println();
        System.out.println("--------------------------------------");
        System.out.println(allList.contains("HHH") ? "lv存在": "lv不存在");
        System.out.println(allList.contains("lv的位置是：" + allList.indexOf("HHH")));
        System.out.println(allList.contains("allList否为空" + allList.isEmpty() ));
        System.out.println("--------------------------------------");
        LinkedList<String> link = new LinkedList<String>();
        link.add("A");
        link.add("B");
        link.add("C");
        link.addFirst("Root");
        link.addLast("End");
        System.out.print(link);
        System.out.println();
        System.out.println("Element: " + link.element());
        System.out.println("Pool: " + link.poll());
        System.out.print(link);
        System.out.println();
        System.out.println("Peek: " + link.peek());
        System.out.print(link);
        System.out.println();
        System.out.println("--------------------------------------");
        for ( int i = 0; i < link.size(); i++)
            {
                System.out.print("Pool: "
                        + "" + link.poll() + "、");
            }
        System.out.println();
        System.out.println("--------------------------------------");
        Set<Person > set = new HashSet<Person>();
//        Set<Person> set = new TreeSet<Person>();
        set.add(new Person("Root2", 12));
        set.add(new Person("AA", 21));
        set.add(new Person("BB", 22));
        set.add(new Person("CC", 22));
        set.add(new Person("CC", 22));
        set.add(new Person("CC", 12));
        System.out.println( set);
        System.out.println("--------------------------------------");
        System.out.println("Iterator: ");
        Iterator<Person> iter = set.iterator();
        while(iter.hasNext())
        {
            System.out.print(iter.next() + "、");
        }
        System.out.println();
        System.out.println("--------------------------------------");
        while(iter.hasNext())
        {
            Person str = iter.next();
            if ("CC".equals(str))
            {
                iter.remove();
            }
            else
            {
                System.out.print(str + "、");
            }
        }
        System.out.println("--------------------------------------");
        Map<String ,String> map = null;
        map = new HashMap<String, String>();
        map.put("04122", "FTL1012");
        map.put("04122076", "FTL");
        map.put("04122078", "1012");
        System.out.println(map.containsKey("04122"));
        System.out.println(map.containsValue("04122"));
        System.out.println("04122 --> " + map.get("04122"));
        System.out.println("--------------------------------------");
        System.out.println("HashMap 中所有的Key:");
        Set<String> sset = map.keySet();
        Iterator<String> it = sset.iterator();
        while (it.hasNext())
        {
            String t = (String) it.next();
            System.out.print( t + "	");
        }
        System.out.println("--------------------------------------");
        System.out.println("HashMap 中所有的Value:");
        Collection<String> co = map.values();
        Iterator<String> itt = co.iterator();
        while (itt.hasNext())
        {
            String tt = (String) itt.next();
            System.out.print( tt + "	");
        }
        System.out.println("--------------------------------------");
        map = new TreeMap<String, String>();
        map.put("04122", "FTL1012");
        map.put("04122076", "FTL");
        map.put("04122078", "1012");
        Set<String> keys = map.keySet();
        Iterator<String> key = keys.iterator();
        System.out.println("TreeMap 中所有的Key:");
        while (key.hasNext())
        {
            String tt =   (String)key.next();
            System.out.print( key + "	");
        }
        System.out.println("--------------------------------------");
        Collection<String> ccc = map.values();
        Iterator<String> ttt = ccc.iterator();
        System.out.println("TreeMap 中所有的Value:");
        while (ttt.hasNext())
        {
            String tt =  (String) ttt.next();
            System.out.print( ttt + "	");
        }
        
        
        System.out.println("--------------------------------------");
    }
};

Map的标准输出示例：

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 HelloFtl { 
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("------------------------------------");
    System.out.println("
foreach方法："); 
    for (String s : values) { 
    System.out.print(s+"、"); 
    } 
    System.out.println("------------------------------------");
    System.out.println("
Iterator方法："); 
    while(iterator.hasNext()){ 
    System.out.print(iterator.next()+"、"); 
    } 
    System.out.println("------------------------------------");
    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("------------------------------------");
    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("------------------------------------");
    System.out.println("Map.entrySet()大小："+map.entrySet().size()); 
    System.out.println("------------------------------------");
}}

Map的迭代输出

package test;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
public class Test
{
    public static void main(String[] args) throws Exception
    {
        Map<String,String> map = new HashMap();
        map.put("hello", "world");
        map.put("hello1", "world1");
        map.put("hello2", "world2");
        map.put("hello3", "world3");
        map.put("hello4", "world4");
        String str = map.get("hello");
        boolean containsKey = map.containsKey("hello");
        boolean containsValue = map.containsValue("world");
        Set<String> keySet = map.keySet();
        Collection<String> values = map.values();

        Iterator<String> iter = values.iterator();
        while(iter.hasNext()){
            String s = iter.next();
            System.out.println(s+"E");
        }
        
    }
}