MANY to MANY mapping using Collections

PFB

Practiced collection scenario:

Between LIST to LIST:

package com.surya.spring;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class Mul {
public static void main(String a[])
{
List l=new ArrayList();
List l1=new ArrayList();
l.add(1);
l.add(2);
l.add(3);
l1.add("banana");
l1.add("orange");
display1(l,l1);
}
public static void display1(List l,List l1)
{
   /*Using Iterator approach between mapping from List to List */
System.out.println("Using Iterator approach between mapping from List to List");
    Iterator itr=l.iterator();
    while(itr.hasNext())
    {
    int next=(Integer) itr.next();
    System.out.println("order id--->"+next+"items---->"+l1.toString()+"Size--->"+l1.size());
    }
    System.out.println(" ");
       System.out.println("using for loop approach between mapping from List to List");
   /*using for loop approach between mapping from List to List */
    for(Object obj:l)
    {
    System.out.println("order id--->"+obj+"items---->"+l1.toString()+"Size--->"+l1.size());
    }
}
 }

Output:

Using Iterator approach between mapping from List to Map
order id---> 1 items---->[banana, Orange, Apple, grapes]  Size--->4
order id---> 2 items---->[tea, Cofee]  Size--->2
order id---> 3 items---->[chicken, mutton, Fish]  Size--->3

using for loop approach between mapping from List to Map
Key : 1 Value : [banana, Orange, Apple, grapes]  Size--->4
Key : 2 Value : [tea, Cofee]  Size--->2
Key : 3 Value : [chicken, mutton, Fish]  Size--->3

Between LIST and MAP:

package com.surya.spring;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

public class Mulm {
public static void main(String a[])
{
List l=new ArrayList();
List itm1=Arrays.asList("banana","Orange","Apple","grapes");
List itm2=Arrays.asList("tea","Cofee");
List itm3=Arrays.asList("chicken","mutton","Fish");
HashMap m=new HashMap();
l.add(1);
l.add(2);
l.add(3);
m.put(1,itm1);
m.put(2,itm2);
m.put(3,itm3);
display(l,m);
}
public static void display(List l,HashMap m)
{
   /*Using Iterator approach between mapping from List to List */
System.out.println("Using Iterator approach between mapping from List to Map");
    Iterator itr=l.iterator();
    while(itr.hasNext())
    {
    int next=(Integer) itr.next();
    Iterator it = m.keySet().iterator();
    while(it.hasNext())
    {
    int key=it.next();
    if(next==key)
        System.out.println("order id---> "+next+" items---->"+m.get(key).toString()+"  Size--->"+((List) m.get(key)).size());

    }
    }
    System.out.println(" ");
       System.out.println("using for loop approach between mapping from List to Map");
    for(Object obj:l)
    {
    //Integer obj1=(Integer)obj;
    //System.out.println(obj1.getClass().getName());
       for (Object key : m.keySet()) {
        //Integer obj2=(Integer)key;
        if(obj==key)
            System.out.println("Key : " + key.toString() + " Value : " + m.get(key)+"  Size--->"+((List) m.get(key)).size());
      }}}}
   

Output:

Using Iterator approach between mapping from List to Map
order id---> 1 items---->[banana, Orange, Apple, grapes]  Size--->4
order id---> 2 items---->[tea, Cofee]  Size--->2
order id---> 3 items---->[chicken, mutton, Fish]  Size--->3

using for loop approach between mapping from List to Map
Key : 1 Value : [banana, Orange, Apple, grapes]  Size--->4
Key : 2 Value : [tea, Cofee]  Size--->2
Key : 3 Value : [chicken, mutton, Fish]  Size--->3

Same Screenshot: