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 + "\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 + "\t");
         }
         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 + "\t");
         }
         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 + "\t");
         }

         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("\nforeach方法：");
     for (String s : values) {
     System.out.print(s+"、");
     }
     System.out.println("------------------------------------");
     System.out.println("\nIterator方法：");
     while(iterator.hasNext()){
     System.out.print(iterator.next()+"、");
     }
     System.out.println("------------------------------------");
     System.out.println("\nMap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()+"\n");
     }
     System.out.println("------------------------------------");
     System.out.println("\nMap的标准输出_2(Foreach)：");
     for (Map.Entry<String, String> entry : entrySet) {
     System.out.print(entry.getKey()+"-->: "+entry.getValue()+"\n");
     }
     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");
         }

     }
 }