Author has experience of developing enterprise large scale applications built with the technologies ranging from Java and frameworks like spring,hibernate,jpa, angularjs.

September 30, 2018 admin java interview questions Leave a Comment

Count length of singly Linked List recursively

class MySingly{
    int data;
    MySingly next;
    int counter;
    public int count(MySingly singly){
        if(singly!=null){
            counter++;
            count(singly.next);
        }
        return counter;
    }
}
public class LengthOfTree {
    public static void main(String[] args){
        MySingly singly=new MySingly();
        singly.data=4;
        MySingly one=new MySingly();
one.data=4;
        singly.next=one;
        MySingly two=new MySingly();
two.data=6;
        singly.next.next=two;
        MySingly three=new MySingly();
three.data=7;
        singly.next.next.next=three;
   System.out.print(singly.count(singly));
    }
}

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class MySingly{

int data;

MySingly next;

int counter;

public int count(MySingly singly){

if(singly!=null){

counter++;

count(singly.next);

}

return counter;

}

public class LengthOfTree {

public static void main(String[] args){

MySingly singly=new MySingly();

singly.data=4;

MySingly one=new MySingly();

one.data=4;

singly.next=one;

MySingly two=new MySingly();

two.data=6;

singly.next.next=two;

MySingly three=new MySingly();

three.data=7;

singly.next.next.next=three;

System.out.print(singly.count(singly));

}

The problem i tried to solve is present in https://www.geeksforgeeks.org/find-length-of-a-linked-list-iterative-and-recursive/ If you liked this post kindly share it with your friends. To prepare for interviews I would recommend

Graph using adjacency matrix in java

Graph using adjancy matrix in java The program in java it adds edges and checks if edge exist between specified vertices.

package com.company;
/**
 * Graph simple example to check if EDGE exist
 * Author:wwww.shivapreals.tech
 */

import java.util.Scanner;

class GraphA{
    int MAX;
    int[][] graph;

    public void addEdge(int x,int y){
        // graph[x][y]=1; 1 error
        graph[x][y]=1;
    }
    public void init(int MAX){
        this.MAX=MAX;
        this.graph=new int[MAX][MAX];
        for(int xaxis=0;xaxis<MAX;xaxis++){
            for(int yaxis=0;yaxis<MAX;yaxis++){
                graph[xaxis][yaxis]=-1;
            }
        }
    }

    public void edgeExist(int i, int i1) {
        if(graph[i][i1]!=-1){
            System.out.print("Edge exist");
        }
    }
}
public class GraphAdjency {
    public static void main(String[] args) {
        GraphA graph = new GraphA();

        System.out.println("Enter Graph 2d size");
        Scanner sc=new Scanner(System.in);
       int MAX=sc.nextInt();//these will be number of rows and columns
        graph.init(MAX);
        graph.addEdge(2,1);
        graph.addEdge(2,3);
        graph.edgeExist(2,1);
    }


}

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package com.company;

/**

* Graph simple example to check if EDGE exist

* Author:wwww.shivapreals.tech

*/

import java.util.Scanner;

class GraphA{

int MAX;

int[][] graph;

public void addEdge(int x,int y){

// graph[x][y]=1; 1 error

graph[x][y]=1;

}

public void init(int MAX){

this.MAX=MAX;

this.graph=new int[MAX][MAX];

for(int xaxis=0;xaxis<MAX;xaxis++){

for(int yaxis=0;yaxis<MAX;yaxis++){

graph[xaxis][yaxis]=-1;

}

public void edgeExist(int i, int i1) {

if(graph[i][i1]!=-1){

System.out.print("Edge exist");

}

public class GraphAdjency {

public static void main(String[] args) {

GraphA graph = new GraphA();

System.out.println("Enter Graph 2d size");

Scanner sc=new Scanner(System.in);

int MAX=sc.nextInt();//these will be number of rows and columns

graph.init(MAX);

graph.addEdge(2,1);

graph.addEdge(2,3);

graph.edgeExist(2,1);

}

If you like this tutorial kindly share it spread the word. You can buy me a coffee my UPI ID chaudharisuresh997@okhdfcbank

September 11, 2018September 11, 2018 admin Data Structure stack, stack implemenatation using java Leave a Comment

Stack Implementation in java

package com.company;

import java.util.ArrayList;
import java.util.List;

class Stack{
    List<Integer> stackList=new ArrayList<>();
    int top=0;

}
public class StackUtil {
    Stack stack=new Stack();

    public int pop()
    {int item = 0;
        if(stack.top!=-1){
    System.out.println(stack.top);
    if(stack.top==0)
    item=stack.stackList.get(stack.top);
    else
        item=stack.stackList.get(stack.top-1);

    stack.top=stack.top-1;
        }else{System.out.println("EMPTY");}
    return item;
    }
    public void push(int data){
    System.out.println(stack.top);

        stack.stackList.add(data);
        stack.top+=1;

    }
    public static void main(String[] args){
        StackUtil util=new StackUtil();
        util.push(45);
        //util.push(55);
        //util.push(70);
        int stackItem=util.pop();
        System.out.println(stackItem);
        System.out.println(util.pop());
        System.out.println(util.pop());
        System.out.println(util.pop());
        System.out.println(util.pop());
    }
}

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package com.company;

import java.util.ArrayList;

import java.util.List;

class Stack{

List<Integer> stackList=new ArrayList<>();

int top=0;

}

public class StackUtil {

Stack stack=new Stack();

public int pop()

{int item = 0;

if(stack.top!=-1){

System.out.println(stack.top);

if(stack.top==0)

item=stack.stackList.get(stack.top);

else

item=stack.stackList.get(stack.top-1);

stack.top=stack.top-1;

}else{System.out.println("EMPTY");}

return item;

}

public void push(int data){

System.out.println(stack.top);

stack.stackList.add(data);

stack.top+=1;

}

public static void main(String[] args){

StackUtil util=new StackUtil();

util.push(45);

//util.push(55);

//util.push(70);

int stackItem=util.pop();

System.out.println(stackItem);

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

}

If you have loved this post kindly consider to donate at UPI chaudhariusuresh997@okhdfcbank Find Source Code at https://github.com/shivapreals/Data-Structure/blob/master/StackUtil.java

April 12, 2018 admin mobile development angular4, ionic2, mobile development, step by step Leave a Comment

How to navigate to other page Navigation tutorial-ionic2 and angular4

How to navigate to other page Navigation tutorial-ionic2 and angular4 While developing some app you most frequently have the requirement to navigate back and forth between the views. In ionic the NavController from ‘ionic-angular’ comes handy.

import { Component } from '@angular/core';
import { NavController } from 'ionic-angular';
import {ContactPage} from '../contact/contact';
@Component({
  selector: 'page-about',
  templateUrl: 'about.html'
})
export class AboutPage {

  constructor(public navCtrl: NavController) {

  }
navigate(){
  this.navCtrl.push(ContactPage);
}
}

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import { Component } from '@angular/core';

import { NavController } from 'ionic-angular';

import {ContactPage} from '../contact/contact';

@Component({

selector: 'page-about',

templateUrl: 'about.html'

})

export class AboutPage {

constructor(public navCtrl: NavController) {

}

navigate(){

this.navCtrl.push(ContactPage);

}

this.navCtrl.push method accepts page where you wish to navigate. About.html

<ion-header>
  <ion-navbar>
    <ion-title>
      
      About
    </ion-title>
  </ion-navbar>
</ion-header>

<ion-content padding>
  <button ion-button (click)="navigate()">Default</button>
    
  

</ion-content>

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<ion-header>

<ion-navbar>

<ion-title>

About

</ion-title>

</ion-navbar>

</ion-header>

<ion-content padding>

<button ion-button (click)="navigate()">Default</button>

</ion-content>

<button ion-button> directive is used in ionic to create button. click event is…

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April 11, 2018April 11, 2018 admin mobile development angular4, ionic Leave a Comment

How to iterate items in ionic2 with angular4 tutorial

Hi Everybody,Ever dreamed of developing mobile app on your own.So good news for you is you can develop mobile app if you know little bit of angular.So today we are going to iterate list of items using ionic2 and angular4. Please have a look at below code.It is self explanatory.

import { Component } from '@angular/core';
import { NavController } from 'ionic-angular';

@Component({
  selector: 'page-about',
  templateUrl: 'about.html'
})
export class AboutPage {
  one1(one:string)
  {
    alert(one);
  }
list=["Shiv","ganesh"]
  constructor(public navCtrl: NavController) {

  }

}

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import { Component } from '@angular/core';

import { NavController } from 'ionic-angular';

@Component({

selector: 'page-about',

templateUrl: 'about.html'

})

export class AboutPage {

one1(one:string)

{

alert(one);

}

list=["Shiv","ganesh"]

constructor(public navCtrl: NavController) {

}

<ion-header>
  <ion-navbar>
    <ion-title>
      About
    </ion-title>
  </ion-navbar>
</ion-header>

<ion-content padding>
<ion-list>
  <ion-item *ngFor="let one of list" (click)="one1(one)">
{{one}}

  </ion-item>
</ion-list>
</ion-content>

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<ion-header>

<ion-navbar>

<ion-title>

About

</ion-title>

</ion-navbar>

</ion-header>

<ion-content padding>

<ion-list>

<ion-item *ngFor="let one of list" (click)="one1(one)">

</ion-item>

</ion-list>

</ion-content>

Live Example https://ionic-fwbhvk.stackblitz.io

February 28, 2018February 28, 2018 admin java tutorial HashMap, Java Collection, java tutorial, Map, Step By Step Tutorial for collection, TreeMap, WeakHashMap Leave a Comment

Map Java Collection Tutorial

Map Stores values in key and value. map does not allow duplicate key. only one null key but any number of null values To synchronize the Map use. Collections.synchronizedMap(yourMapObject) Hashmap Hashmap allows random storage sequence is not maintained. Stores values in key and value. Hashmap is not synchronized. Collections.synchronizedHashset Hashmap does not allow duplicate key. Hashmap allows only one null…

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February 28, 2018 admin java tutorial collection, hashset, java in 24 hours, set tutorial in java, treeset Leave a Comment

Java Collection -Set

<I>Set does not contain duplicates. randomly stores elements. does not permits null elements. How to make your list synchronised? Collections.synchronizedSet(yourSetObject) Classes <C>TreeSet Sorts element by natural order. rest of the properties are same as specified by interface Set Internally it is implemented using the TreeMap. Main purpose is for sorting the stores elements. …

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February 14, 2018February 14, 2018 admin Data Structure Data structure algorithm in java, Doubly Linked List in java Leave a Comment

Doubly Linked list in java

Doubly Linked List Tutorial in Java

class DoublyList
{
	DoublyList prev;
	DoublyList next;
	String data;
	
}
class DoublyAPI
{
	DoublyList head;
	
	/**
	 * Append at last
	 * @param data
	 */
	public void appendToDoublyList(String data)
	{
		if(head==null)
		{
			head=createNode(data);			
		}
		else
		{
			DoublyList traverseNode;
			traverseNode=head;
			//traverse till end
			while(traverseNode.next!=null)
			{
				traverseNode=traverseNode.next;
			}
			DoublyList newNode=createNode(data);
			
			traverseNode.next=newNode;
			newNode.prev=traverseNode;
			newNode.next=null;
		}
	}
	public void insertInMiddle(int loc,String data)
	{	
		DoublyList traverseNode = head;
		for(int i=0;i<loc;i++)
		{
			traverseNode=traverseNode.next;
		}
		DoublyList newNode=createNode(data);
	
		newNode.next=traverseNode.next;
		traverseNode.next=newNode;
		newNode.prev=traverseNode;
		newNode.next.prev=newNode;
		
		
	}
	/**
	 * Create A node
	 * @param data
	 * @return
	 */
	
	public DoublyList createNode(String data)
	{
		DoublyList doublyObj=new DoublyList();
		doublyObj.data=data;
		return doublyObj;
	}
	public void printAll()
	{
		while(head!=null)
		{
			System.out.println(head.data);
			head=head.next;
		}
		//System.out.println(head.data);
	}

}
public class DoublyLinkedList {




	public static void main(String[] args) {
		DoublyAPI apiObj=new DoublyAPI();
		apiObj.appendToDoublyList("A");
		apiObj.appendToDoublyList("B");
		apiObj.appendToDoublyList("C");
		apiObj.insertInMiddle(1, "Z");
		apiObj.printAll();
	}

}

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class DoublyList

{

DoublyList prev;

DoublyList next;

String data;

}

class DoublyAPI

{

DoublyList head;

/**

* Append at last

* @param data

*/

public void appendToDoublyList(String data)

{

if(head==null)

{

head=createNode(data);

}

else

{

DoublyList traverseNode;

traverseNode=head;

//traverse till end

while(traverseNode.next!=null)

{

traverseNode=traverseNode.next;

}

DoublyList newNode=createNode(data);

traverseNode.next=newNode;

newNode.prev=traverseNode;

newNode.next=null;

}

public void insertInMiddle(int loc,String data)

{

DoublyList traverseNode = head;

for(int i=0;i<loc;i++)

{

traverseNode=traverseNode.next;

}

DoublyList newNode=createNode(data);

newNode.next=traverseNode.next;

traverseNode.next=newNode;

newNode.prev=traverseNode;

newNode.next.prev=newNode;

}

/**

* Create A node

* @param data

* @return

*/

public DoublyList createNode(String data)

{

DoublyList doublyObj=new DoublyList();

doublyObj.data=data;

return doublyObj;

}

public void printAll()

{

while(head!=null)

{

System.out.println(head.data);

head=head.next;

}

//System.out.println(head.data);

}

public class DoublyLinkedList {

public static void main(String[] args) {

DoublyAPI apiObj=new DoublyAPI();

apiObj.appendToDoublyList("A");

apiObj.appendToDoublyList("B");

apiObj.appendToDoublyList("C");

apiObj.insertInMiddle(1, "Z");

apiObj.printAll();

}

This is just like a tip of the iceberg.I would strongly recommend to go through

February 13, 2018February 14, 2018 admin Data Structure Data structure algorithm in java, easy guide to data structure, java tutorial, linked list with java tutorial, step by step linkedlist tutorial Leave a Comment

Singly Linked List using java.

Singly Linked list using java Singly Linked List is created for adding the elements one after another where each Node is linked to the other Node sequentially. The operations covered in this post are Append to the end Add in the middle of linked list. Append to the end How we are going to create linked…

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February 13, 2018February 13, 2018 admin java tutorial each file read by new thread, java simple tutorial, multithreading, simplle mutilthreading example Leave a Comment

Files Read by Multiple Thread

How to read each file on separate thread. Step 1:Get List of all files in the specified folder

String[] files=new File("D:\\test\\").list();

Now pass the file to the seperate thread.

for(String file:files)
{
new Thread(new FileList("D:\\test\\"+file)).start();
}

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String[] files=new File("D:\\test\\").list();

Now pass the file to the seperate thread.

for(String file:files)

{

new Thread(new FileList("D:\\test\\"+file)).start();

}

Step 2:Create Class which will display contents of file and implements runnable. Note that I have created constructor to pass the filelocation to the thread,

class FileList implements Runnable
{
String fileLoc;
FileList(String file)
{
this.fileLoc=file;
}
Whatever process i need to do I will only write it in run()

public void run()
{

readFile(fileLoc);
}

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class FileList implements Runnable

{

String fileLoc;

FileList(String file)

{

this.fileLoc=file;

}

Whatever process i need to do I will only write it in run()

public void run()

{

readFile(fileLoc);

}

Now read file logic will only read contents of file using java8…

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