Find the number which occurs odd number of time. All numbers occur even number of times except one.

import java.util.HashMap;
import java.util.Map;

public class Test {

 public static void main(String[] args) {

  //integer array declared with values
  int array[] = { 20, 40, 50, 40, 50, 20, 30, 30, 50, 20, 40, 40, 20};

  //declared map
  Map<Integer, Integer> map = new HashMap<>();

  //iterating int array to get the frequency of numbers
  for (int i = 0; i < array.length; i++) {
   if (map.containsKey(array[i])) {
    Integer value = (Integer) map.get(array[i]);

    map.put(array[i], ++value);
   } else {
    int key = array[i];

    map.put(key, 1);
   }
  }
  //iterating map to get the number which is present odd times
  map.forEach((key, value) -> {
      if(value % 2 != 0) {
       System.out.print("Number which occurs odd number of times is : 
       "+key);
      }
  });
 }
}

Read More

How to parse data from String in java.

package com.problem;



import java.util.regex.Pattern;



import org.apache.commons.lang3.StringUtils;



public class Solution {



 public static void main(String[] args) {



  String str = "234$$##Shivaji$$##22.00";

  String patternStr = "[^A-Za-z0-9.]";



  Pattern pattern = Pattern.compile(patternStr);



  String[] s = pattern.split(str);

  String name = null;

  Double doub = null;

  Integer in = null;

  for (String ss : s) {



   if (StringUtils.isAlpha(ss)) {

    name = ss;

   } else if (StringUtils.isBlank(ss)) {



   } else if (StringUtils.isAlphanumeric(ss)) {

    in = Integer.valueOf(ss);

   } else {

    doub = Double.valueOf(ss);

   }

  }

  System.out.println(name);

  System.out.println(doub);

  System.out.println(in);



 }

}

Read More

Java program to find the occurence of integer in a given integer array.

package com.javatechtube;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class IntegerOccurence {

  public static void main(String[] args) {

 int[] arr = {1,2,3,2,4,5};

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

 Map<Integer, Integer> map = new HashMap<>();

 for(int i=0; i<arr.length;i++)
        {
    if(map.containsKey(arr[i]))
           {
  Integer value = (Integer)map.get(arr[i]);

  map.put(arr[i],++value);
    }
           else
           {
                int key = arr[i];

  map.put(key, 1);

  list.add(arr[i]);
    }
  }
         System.out.println(map);
     }
}

Read More

Java program to add all numbers present in AlphaNumeric String

First Approach

package com.nt.logical;

import java.util.Scanner;

public class AddNoFromString 
{
 public static void main(String[] args) 
 {
  //getting the dynamic values from keyboard
  Scanner sc=new Scanner(System.in);
  System.out.println("Enter the String with number: ");
  String str=sc.nextLine();

  //logic for removing the alpha characters
  String[] s=str.split("[A-Za-z]");
  String ss="";

  //logic to remove white spaces
  for(int i=0;i<s.length;i++)
  {
   ss=ss+String.valueOf(s[i]);
  }
  
  //getting number from ss obj
  int num=Integer.valueOf(ss);
  int sum=0;
  
  //logic to add the numbers
  while(num>0)
  {
    sum=sum+num%10;
    num=num/10;
  }
  //printing the value after adding
  System.out.println("Value :"+sum);
 }
}

Second Approach

package com.nt.logical;

import java.util.Scanner;

public class AddNoFromString 
{
 public static void main(String[] args) 
 {
  //getting the dynamic values from keyboard
  Scanner sc=new Scanner(System.in);
  System.out.println("Enter the String with number: ");
  String str=sc.nextLine();

  //logic for removing the characters
  String[] s=str.split("[A-Za-z]");
  int sum=0;

  //logic to add the numbers
  for(int i=0;i<s.length;i++)
  {
    if(!(sArr[i].equals("")||(sArr[i].isBlank())))
    {
      sum=sum+Integer.parseInt(s[i]);
    }
  }
  //printing the value after adding
  System.out.println("Value :"+sum);
 }
}

Read More

Java program to create a custom Collection(ArrayList)

MyList.java(Interface)

package com.nt.util;

public interface MyList {

 public void add(Object obj);
}

MyArrayList.java(Class)

package com.nt.util;

public class MyArrayList implements MyList{

 private Object[] objArray;
 private static int elementCount=0;
 
 //default constructor
 public MyArrayList() {
  
  //initial size
  this.objArray=new Object[4];
 }
 
 //Logic to add elements
 public void add(Object obj) {
  
  //checks if capacity is == size
  if(this.capacity()==this.size())
  {
   //then it will create a new array
   Object[] tempArray=new Object[this.capacity()*2];
   int i=0;
   
   //it will copy all the element to new array
   for(;i<(this.size());i++)
   {
    tempArray[i]=this.objArray[i];
    
   }
   
   //it will insert the last element
   tempArray[elementCount++]=obj;
   
   //it will copy tempArray to objArray
   this.objArray=tempArray;
  }
  else
  {
   
   this.objArray[elementCount++]=obj;
   
  }
 }
 
 //returns the capacity
 private int capacity() {
  return this.objArray.length;
 }
 
 //returns the size
 private int size()
 {
  return elementCount;
 }
 
 @Override
 public String toString()
 {
  String str=java.util.Arrays.toString(this.objArray);

  return str.replaceAll("null","");
 }

}

ArrayListTest.java

package com.nt.test;

import com.nt.util.MyArrayList;
import com.nt.util.MyList;

public class ArraylistTest {

 public static void main(String[] args) {
  
  MyList list=new MyArrayList();
  list.add(23);
  list.add(45);
  list.add(43);
  list.add(3);
  list.add(55);
  System.out.println(list);
  
 }
}

Read More

Java program to create upto 3 object for a class and throw Userdefined Exception if trying to create 4th one

ObjectCreation.java

package com.nt.object;

public class ObjectCreation{

 private static int count=0;
 private ObjectCreation()
 {
  count++;
 }
 public static ObjectCreation getInstance()
 {
  if(count<3)
   return new ObjectCreation();
  else
   throw new ObjectCreationOutOfBoundException("Can't create more than three objects!!!");
 }
}

ObjectCreationOutOfBoundException.java

package com.nt.object;

public class ObjectCreationOutOfBoundException extends RuntimeException {

 public ObjectCreationOutOfBoundException(String s)
 {
  super(s);
 }
}

Test.java

package com.nt.object;

public class Test {

 public static void main(String[] args) {
 
  ObjectCreation obj1=ObjectCreation.getInstance();
  System.out.println("Created first object : "+obj1);
  
  ObjectCreation obj2=ObjectCreation.getInstance();
  System.out.println("Created second object : "+obj2);
  
  ObjectCreation obj3=ObjectCreation.getInstance();
  System.out.println("Created third object : "+obj3);
  
  //here exception will generate
  ObjectCreation obj4=ObjectCreation.getInstance();
 }
}

Read More

Generate Alpha Numeric String for the given size

import java.util.Random;
import java.util.Scanner;

public class GenerateAlphaNumericStringUsingGivenNo {

 public static void main(String[] args) {
  
  Scanner sc=null;
  int size=0; 
  System.out.println("Enter the size");
  sc=new Scanner(System.in);
  //taking the size from the keyboard
  size=sc.nextInt();
  
  //calling the method to generate AlphaNumericString
  System.out.println(generate(size));
  
  
 }
 
 //method for generating AlphaNumericString 
 public static String generate(int size)
 {
  Random rand=null;
  StringBuffer sb=null;
  String numAndChars=null;
  
  //all string which will be choosen to generate
  numAndChars="abcdefghijklmnopqrstuvwxyz"
     +"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
     +"0123456789";
  
  rand=new Random();
  sb=new StringBuffer("");
  
  for(int i=0;i<(size);i++)
   {
    //logic to generate AlphaNumeric String
    int index=(int)(numAndChars.length()*Math.random());
    
    //appending the characters one by one 
    sb.append(numAndChars.charAt(index));
   }
  //returning the AlphaNumeric String
  return sb.toString();
 }
}

Read More