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Java Program that Shows Use of Collection Interface

  • Last Updated : 14 Sep, 2021

The Collection framework is a unified architecture for representing and manipulating collections, enabling collections to be manipulated independently of implementation details.

Uses and advantages of Collection Framework:

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  • This reduces the efforts of programmers by providing data structures and algorithms, so we do not have to write them.
  • This increases performance by providing a high-performance implementation of data structures and algorithms.
  • This provides interoperability between unrelated APIs by establishing a common language to pass collections back and forth.
  • Reduces the effort required to learn APIs by requiring you to learn multiple ad hoc collection APIs.
  • This provides static methods that perform useful functions on collections, such as sorting a list.
  • This provides Wrapper implementation which adds functionality, such as synchronization, to other implementations.

And many more advantages it provides for us to use and tackle the problems of development.

Usages: Examples of different types of Interfaces are given below:



  1. List Interface
  2. Liked List
  3. Map Interface 
  4. Stacks

Use Case 1: List Interface

Java




// Java Program that Shows Use of Collection Interface
// ArrayList
 
import java.util.*;
 
class GFG {
    public static void main(String args[])
    {
        ArrayList<String> list = new ArrayList<String>();
        list.add("Geeks");
        list.add("areyou");
        list.add("working");
        list.add("hard?");
 
        Iterator itr = list.iterator();
        while (itr.hasNext()) {
            System.out.println(itr.next());
        }
    }
}
Output
Geeks
areyou
working
hard?

Use Case 2: Linked List

Java




// Java Program that Shows Use of Collection Interface
// LinkedList
 
import java.util.*;
 
// Class testing java Collection
public class GFG {
 
    // Main driver method
    public static void main(String args[])
    {
        // Creating a LinkedList
        LinkedList<String> al = new LinkedList<String>();
 
        // Adding elements to above linked list
        al.add("Geeks");
        al.add("areyou");
        al.add("working");
        al.add("hard?");
 
        // Iterator
        Iterator<String> itr = al.iterator();
 
        // Condition check over elements inside using
        // hasNext() method which holds true till there is
        // element inside list
        while (itr.hasNext()) {
 
            // Printing elements of LinkedList
            System.out.println(itr.next());
        }
    }
}
Output
Geeks
areyou
working
hard?

Use Case 3: Map Interface 

Java




// Java Program that Shows Use of Collection Interface
// Hash-Map
 
import java.util.*;
public class GFG {
 
    // Main driver method
    public static void main(String[] args)
    {
        // Creating a Map
        Map<Integer, String> map = new HashMap<>();
 
        // Adding elements to map
        map.put(1, "Geeks");
        map.put(2, "are");
        map.put(3, "you");
        map.put(4, "working");
 
        // Traversing Map
        // Converting to Set so that traversal is accessed
        Set set = map.entrySet();
 
        // Iterator
        Iterator itr = set.iterator();
 
        // Condition check over elements inside using
        // hasNext() method which holds true till there is
        // element inside list
 
        while (itr.hasNext()) {
            // Converting to Map.Entry so that we can get
            // key and value separately
 
            Map.Entry entry = (Map.Entry)itr.next();
 
            // Printing elements inside HashMap
            System.out.println(entry.getKey() + " "
                               + entry.getValue());
        }
    }
}
Output
1 Geeks
2 are
3 you
4 working

Use Case 4: Stacks 

Java




// Java Program that Shows Use of Collection Interface
// Stack
 
import java.util.*;
public class GFG {
 
    // Main driver method
    public static void main(String args[])
    {
        // Creating a stack in memory
        Stack<String> stack = new Stack<String>();
 
        // Adding elements to stack
        stack.push("Geeks");
        stack.push("are");
        stack.push("you");
        stack.push("working");
        stack.push("hard?");
 
        // pop() returns all elements of stack
        stack.pop();
 
        //. iterator
        Iterator<String> itr = stack.iterator();
 
        // Condition check over elements inside using
        // hasNext() method which holds true till there is
        // element inside list
        while (itr.hasNext()) {
 
            // Print all popped elements
            System.out.println(itr.next());
        }
    }
}
Output
Geeks
are
you
working



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