Data Structure and Algorithms in Java

                               

Data Structures :

It is a container of data. It let us store data more effectively. Execution and manipulation of data become's more easy and fast with the help data structures. It provides a bunch of ways to store data.

Large projects contain complex requirements, those projects need to be faster and user-friendly. There are many requirements those can't be implemented without data structures. Data structures provide many algorithms to do so.

Topics

• Stack
• Queue
• Linked List
• Sorting
• Hash tables 
• Trees
• Application Development

Stack :
Is the linear data structure which follows the order in which the operations 
are performed .
The major operations which performed in Stacks are

• Push : Used to insert the data
• Pop : Used to access the data
• isEmpty : Used to check whether the stack is empty

There are two ways to implement stacks 
1. Array
2. LinkedList

Sample example on Stack using array:

package datastr;



public class InStack {

 private int [] stack;

 private int top;

 private int size;

 public InStack(){

  top=-1;

  size= 50;

  stack= new int[50]; 

 }

 public InStack(int size){

  top=-1;

  this.size=size;

  stack =new int[this.size];

 }

 

 public boolean push(int item){

  if(!isFull()){

  top++;

  stack[top]=item;

  return true;

  }else{

   return false;

  }

 }

 

 public int pop(){

  try {

   return stack[top--];

  } catch (Exception e) {

   // TODO Auto-generated catch block

   e.printStackTrace();

   return -1;

  }

 }

 

 public boolean isFull(){

  return(top== stack.length-1);

 }



 public boolean isEmpty(){

  return(top== -1);

 }

}

********************************************



package datastr;

public class Main {



public static void main(String[] args){

  InStack inStack = new InStack();

  if(!inStack.isFull()){

   inStack.push(2);

   inStack.push(4);

   inStack.push(6);

   inStack.push(9);

  }

  System.out.println(inStack.pop());

  System.out.println(inStack.pop());

  System.out.println(inStack.pop());

  System.out.println(inStack.pop());

  System.out.println(inStack.pop());

  System.out.println(inStack.pop());



 }



}

Queue :

Queue is an another type of data structure, the way of storing and retrieving the data from queue first in and first out.

The major operations performed on Queue are :

• Enqueue : Adds the item to queue
• Dequeue : Removes the item from queue
• Front  : Item at first index 
• Rear : Item at last index