Java Algorithms Trees

A tree will have a root node on its top and it has child and child have child.  Node with out child are called leaf. A Binary Tree contains nodes with two children always.Each node has left node and right node.  Binary search tree is a binary tree having specific ordering. Here always left node contains lesser and right node...

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Java Algorithms Bubble Sort

Bubble Sort is the simplest sorting algorithm that works by repeatedly swapping the adjacent elements if they are in wrong order.   Getting each element one by one and comparing it with adjacent elements and swapping the positions. public void bubbleSort() { int temp, firstValue, secondValue; int[] arr = { 1, 90, 25, 22, 4, 50 }; printArray(arr); for (int i = 0; i < arr.length; i++) { ...

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Java Algorithms Linear Search

A linear search traverse down a list, one item at a time, without jumping. public String linearSearchForValue(int value) { String indexesWithValue = ""; for (int i = 0; i < size; i++) { if (theArray[i] == value) { indexesWithValue += i + " ,"; } } return indexesWithValue; } .sk-code { background-color: #ebebeb !important; padding: 0px 6px 5px 18px !important; ...

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Travesrse Matrix Diagonally in Java

A matrix will be in M x N format.So what we need to do is, get value of indexes from 0,0 to M,N. Itreate the two dimensional array in diagonally as follow 50 36 22 31 88 87 27 73 95 After diagonal traverse the output will be. 50 31 36 27 88 22 73 87 95 Consider the above output 50 31 36 27 88 22 These elements start from left to right top Need to iterate for 0 to M-1 using for loop and display corresponding...

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Traverse the matrix as spiral in Java

A matrix will be in M x N format.So what we need to do is, get value of indexes from 0,0 to m,n. Itreate the two dimensional array in spiral mode as follow we need to traverse matrix and remove the row/column which already traversed. We are not going to delete the elements instead we will limit it by defining boundaries.  Boundaries...

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Traverse the matrix in Java

Traverse the matrix in Java A matrix will be in M x N format. So what we need to do is, get value of indexes from 0,0 to m,n.   Itreate the two dimensional array as follow take 0(i) and traverse j till j < N take 1(i) and traverse j till j < N            .            . till M(i) and traverse j till j < N       PrimeNumberCheck.java ...

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Check number is prime or not

To check the given number is prime or not. Prime Numbers: A prime number (or a prime) is a natural number greater than 1 that has no positive divisors other than 1 and itself.  It means the remainder of divison of N with numbers from 2 to N/2 should be grater than zero. Lets take 6  6%2=0, 6%3=0...from 2 to 3(2 to 6/2) here remainder is zero. So 6 is not prime number. Lets take 5 now 5%2=1 here remainder is greater...

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Order of Execution in java Inheritance

Order of Execution Parent Static Block  Child Static Block  Parent Normal Block  Parent Constructor  Child Normal Block  Child Constructor Child method invoked Animal.java  public class Animal { static { System.out.println("Animal Static Block "); } public Animal() { System.out.println("Animal Consuctor"); } { System.out.println("Animal Normal Block"); } public...

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Java Spring Interview Questions

Load application Context on Spring? ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml"); Autowired @Autowired private ApplicationContext appContext; Spring bean scopes: session and globalSession GlobalSession is something which is connected to Portlet applications. When your application works in Portlet container it is built of some amount of portlets. Each portlet has its...

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Write a code to create deadlock in java

public class DeadLockEx { private String str1 = "SPRING"; private String str2 = "HIBERNATE"; public static void main(String[] args) { DeadLockEx app = new DeadLockEx(); app.t1.start(); app.t2.start(); } Thread t1 = new Thread("Thead 1") { public void run() { while (true) { synchronized (str1) { synchronized (str2) { System.out.println(str1 + str2); ...

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Java Oops Interview Questions

Implementing two interfaces in a class with same method. Which interface method is overridden?  interface A{ int f(); } interface B{ int f(); } class Test implements A, B{ public static void main(String... args) throws Exception{ } @Override public int f() { // from which interface A or B return 0; } } If a type implements two interfaces, and each interface define a method that has...

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Two Sum on arrays

Given an array of integers, return indices of the two numbers such that they add up to a specific target. Example: Given nums = [ 3, 4, 5, 2, 10, 8, 9 ] target = 19 Because nums[4] + nums[6] = 10 + 9 = 19, return [4, 6] Approach: step1. take 3 and then add 3 with all other elements step2. take 4 and then add 4 with all other elements.Continue same till 9         TwoSum.java  ...

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Java JDBC Datasouce

Data Source Objects is a factory of connections to physical data sources. To use datasource, We need to configure the data source in the naming service of JBoss or Tomacat. Webapplication can use JNDI lookup to get the datasource and using that data source we can create the connections. The interface Datasource is packaged inside javx.sql...

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Switching Case of String

All the uppercase letters should be converted to lowercase and all the lowercase letters should be converted to uppercase         StringCaseSwith.java   import java.util.Scanner; /** * all the uppercase letters should be converted to lowercase and all the * lowercase letters should be converted to uppercase */ public class StringCaseSwith { public static void main(String[] args)...

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Find missing number between 1 to N with low time complexity

Need to find missing number between 1 to N with low time complexity O(n). Step1: Get sum of natural numbers from 1 to N as N x(N+1)/2 Step2: Get sum of array elements Step3: Missing number = natural numbers sum - array sum       FindMissingNumber.java public class FindMissingNumber { private static final int END_NUMBER = 10; private int getMissingNumber(int[] arr) { int missingNum = 0; ...

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When to use Abstract class and When to use Interface in Java

Abstraction is one among the oops concepts and it means hiding the implementation details.In java abstraction can be achieved by two methods. 1. Abstract Class 2. Interface       Abstract Class Abstract class contains both unimplemented and implemented methods. Abstratct class must have the keyword abstract and it may not contains any abstract method. If it acontains any abstract method then all...

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Set Implementation in Java

Set conatins only unique elements. HashSet achieves uniqueness of its elements by using hashmap Whenever we create an object of hashset inernally it will create an object of hashmap. If we add an element into a set it will store as key for map. But same time we need a value for key. That value can be Object instance.So whenever we add an element to set it will create Hash map entry with key as added element and value...

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Java Hashmap Implementation

.sk-code { background-color: #EFF0F1 !important; padding: 0px 6px 5px 18px; display: block; white-space: pre-wrap; } Hashmap stores key value pairs HashMap uses hash to insert and get elements. hash = key.hashCode()%BUCKET_ARRAY_SIZE] Its an array of Entry LinkedList...

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Lifecycle and States of a Thread

.sk-code { background-color: #EFF0F1 !important; padding: 0px 6px 5px 18px; display: block; white-space: pre-wrap; } A thread in Java at any point of time exists in any one of the following states. New Runnable Blocked Waiting Timed Waiting Terminated ...

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