java --Using the Map Interface

1.HashMap Class

示例代码：

package self;

import java.util.HashMap;

public class HashMapDemo {
    public static void main(String args[]) {
        HashMap<String,Integer> obj=new HashMap<String,Integer>();
        Integer iobj1=new Integer (11);
        Integer iobj2=new Integer (22);
        Integer iobj3=new Integer (33);
        Integer iobj4=new Integer (44);
        
        System.out.println("Size of HashMap is :"+obj.size());
        obj.put("L1", iobj1);
        obj.put("L2",iobj2);
        obj.put("L3",iobj3);
        obj.put("L4",iobj4);
        obj.put("L5", iobj1);
        
        System.out.println("
HashMap after adding the objects:"+obj);
        System.out.println("Size of HashMap after adding objects:"+obj.size());
        obj.remove("L3");
        obj.remove("L5");
        
        System.out.println("
HashMap after removing the objects:"+obj);
        System.out.println("Size of the HashMap after removing objects: "+obj.size());
    }
}

测试结果：

2.TreeMap Class

示例代码：

package self;

import java.util.TreeMap;

public class TreeMapDemo {
    public static void main(String args[]) {
        TreeMap<Integer,String> obj=new TreeMap<Integer,String>();
    
        String sobj1=new String("Value 1");
        String sobj2=new String("Value 2");
        String sobj3=new String("Value 3");
        String sobj4=new String("Value 4");
        
        
        System.out.println("Size of TreeMap is :"+obj.size());
        
        obj.put(101, sobj1);
        obj.put(102,sobj2);
        obj.put(103,sobj3);
        obj.put(104,sobj4);
        obj.put(105, sobj1);
        
        System.out.println("
TreeMap after adding the objects:"+obj);
        System.out.println("Size of TreeMap after adding objects:"+obj.size());
        obj.remove(103);
        obj.remove(105);
        
        System.out.println("
TreeMap after removing the objects:"+obj);
        System.out.println("Size of the TreeMap after removing objects: "+obj.size());
    }
}

测试结果：

3.HashMap Class

示例代码：

package self;

import java.util.Hashtable;

public class HashtableDemo {
    public static void main(String args[]) {
        Hashtable<Integer,Double> obj=new Hashtable<Integer,Double>();
    
        Double dobj1=new Double(55.6);
        Double dobj2=new Double(34.6);
        Double dobj3=new Double(98.6);
        Double dobj4=new Double(12.5);
        
        
        System.out.println("Size of Hashtable is :"+obj.size());
        
        obj.put(55, dobj1);
        obj.put(60,dobj2);
        obj.put(65,dobj3);
        obj.put(70,dobj4);
        obj.put(75, dobj1);
        
        System.out.println("
Hashtable after adding the objects:"+obj);
        System.out.println("Size of Hashtable after adding objects:"+obj.size());
        obj.remove(65);
        obj.remove(75);
        
        System.out.println("
Hashtable after removing the objects:"+obj);
        System.out.println("Size of the Hashtable after removing objects: "+obj.size());
    }
}

测试结果：