Sort HashMap/TreeMap based on value

How to sort HashMap/TreeMap based on value ?

Solution Logic: First we will have a normal HashMap/Treemap object and put some objects to it. Then we will put the same object to another TreeMap object.

class ValueComparator implements Comparator{
    Map map;
    public ValueComparator(Map map) {
        this.map=map;
    }    
    public int compare(Object o1, Object o2) {
		int i1=(Integer)map.get(o1); 
		int i2=(Integer)map.get(o2); 		
		return i1-i2;
        //return i1.compareTo(i2);//If i1 and i2 were of Class type instead of primitives
    }    
}

public class Manager {
	public static void main(String[] args){
		
        Map map=new HashMap();
        map.put("B", 5);
        map.put("A", 4);
        map.put("C", 2);
        map.put("E", 3);
        map.put("D", 1);
        map.put("G", 7);
        map.put("F", 6);        
        
        System.out.println("Before sorting:"+map);        
        Map map2=new TreeMap(new ValueComparator(map));
        map2.putAll(map);//only when you start putting the objects again, it will start re-arranging
        System.out.println("After sorting:"+map2);       	
	}
}

Below is another example using an class type (Employee object):

class Employee implements Comparator{
	int age;
	Map map;
	public Employee(int age) {
		this.age=age;
	}
	public int compare(Object o1, Object o2) {
		
		Employee e1=(Employee)o1;
		Employee e2=(Employee)o2;
		return e1.age - e2.age;		
	}	
	public String toString() {
		return String.valueOf(age);
	}
}

class ValueComparator implements Comparator{
	Map map;
	public ValueComparator(Map map) {
		this.map=map;
	}	
	public int compare(Object o1, Object o2) {		
		Employee e1 = (Employee) map.get(o1);
		Employee e2 = (Employee) map.get(o2);
		return e1.age - e2.age;
	}	
}

public class Manager{
	public static void main(String[] args) {
		Employee e1=new Employee(41);
		Employee e2=new Employee(35);
		Employee e3=new Employee(10);
		
		Map map=new TreeMap(new Employee(5));//
		
		map.put(e1, e2);
		map.put(e3, e3);
		map.put(e2, e1);		
		
		System.out.println(map);
		Map map2=new TreeMap(new ValueComparator(map));
		map2.putAll(map); //only when you start putting the objects again, it will start re-arranging
		System.out.println(map2);		
	}		
}