Thursday, February 26, 2015

Encrypting and Decrypting Images Using BlowFish

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Blowfish is a symmetric-key block cipher, designed in 1993 by Bruce Schneier and included in a large number of cipher suites and encryption products.
For more information, refer to http://en.wikipedia.org/wiki/Blowfish_(cipher)

To Encrypt and Desrypt Images , follow following steps

Encrypting and Decrypting Images Using BlowFish :
1. Create SecretKey which will be used for Encryption
SecretKey secretKey = new SecretKeySpec(password.getBytes(), "Blowfish");

2. Create Cipher Instance
Cipher cipher = Cipher.getInstance("Blowfish");

3. To Encrypt, Initialize Cipher using secretKey
cipher.init(Cipher.ENCRYPT_MODE, secretKey);

Sunday, December 28, 2014

Scheduling Task using Timer in Java

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Java provides class called Timer using which you can schedule task at specific intervals.

Signature of Schedule method of Timer class follows as 
schedule(TimerTask task, Date firstTime, long period)

Here, task is the task to be executed
firstTime is firstTime at which task to be executed first
period is interval time in milliseconds at which task will be executed automatically at this interval.

Saturday, December 27, 2014

Creating Thread using Extend and Runnable in Java

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In Java, You can create thread using 2 ways.

1. Using extend Thread
  •  MyThread t1 = new MyThread("Thread t1"); 
  • where MyThread is class which extends Java's Thread Class.
2. Using implements Runnable
  •    MyRunnable runnable = new Runnable();
  •    Thread t1 = new Thread(runnable,"Thread t1");   
  •     where MyRunnable is class which implements Runnable Interface.

Friday, December 26, 2014

Implement your own LinkedList using Java

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LinkedList consist of Nodes where each Node represent two things. One is Data and other is reference to Next node.

Let's check How you can create your own LinkList Implementation :)
  1. Create Node class containing two things. Object (basically data which node will hold) and Node which is reference to Next Node
  2. Create Your Own linkedList class which will have following methods.
    1. add(Object data) - add element to tail of LinkedList
    2. add(Object data,int index) - create new Node and add that new node containing given data at specific index.

Wednesday, December 17, 2014

Immutable Collections Vs Unmodifiable Collections in Java

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Unmodifiable Collection is kind of collection which is readonly view of Collections. You can not do modification into this kind of collections. They always present Latest Value. If any of source collection changes then unmodifiable collection contains those changes.

While Immutable Collections are such kind of Collection which is readonly copy of Collections. They can not be modified. if any of source collection changes then immutable collections will not reflect with changes.

Saturday, December 13, 2014

Runtime Polymorphism in Java

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Polymorphism means ability to take more than one form. In RunTime Polimorphism resolution to call to method is determined at runtime rather than compile time.
  • Method are overriden but data member are not so runtime polymorphism is not applied to data members

Saturday, July 19, 2014

Insertion Sort Algorithm using Java

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Insertion Sort is simple sort algorithm. In insertion sort, we pickup element and find correct place of element where it needs to be inserted and insert that element at correct place by moving elements to right side.We will keep doing same until we have all sorted elements available on left side.

Quick Sort Algorithm using Java

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Quick Sort works on Divide and Conquer algorithm. Here, given array is divided into two parts, left and right. and both array are being sorted individually. After then we combine and will have sorted array.

How it works:
  1. Pick up any element in Array. ex. middle element of array. we called this one as Pivot.
  2. All elements which are smaller than Pivot are placed in one array and All elements which are larger than pivot are placed in another array
  3. Using recursion sort both array using quicksort
  4. Combine array as mentioned below.

Bubble Sort Algorithm using Java

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In Bubble Sort, smaller elements bubbles to top of list in ascending sorting hence it's called Bubble Sort.

How it works :
  1. In Bubble Sort, You take first element and second element initially and compare both elements.
  2. If second element is smaller than first element then you swipe places. how? using temp :) as below
  3. You keep doing same meaning stepping through array and comparing element with pair of adjacent elements until no swapping required and you have sorted array

Binary Search Algorithm using Java

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Binary search works faster than sequential search.It search on sorted elements.
In Binary Search, Let's say You have an array and you want to search specific item in array

How it Works :
  1. Initialize low=0 and high as max length of search array - 1.
  2. while low<=high each item you, take middle element of array and if given searchItem is less than middle element then you need to search in array of elements array which are less than middle element. Hence, high = middle - 1