Java program to find the biggest palindrome from the given string.

  package com.demo;

import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;

public class PlaindromTest {

	public static void main(String[] args) {

		String str = "my as a aaaaaa mom madam";
		biggestPlainDrom(str);
	}

	private static void biggestPlainDrom(String str) {

		StringBuilder builder = new StringBuilder();
		int size = 0;
		List list = new CopyOnWriteArrayList();

		String[] strArr = str.split(" ");
		
		for (String st : strArr) {

			for (int i = st.length() - 1; i >= 0; i--) {

				builder.append(st.charAt(i));
			}
			if (builder.toString().equals(st)) {
				if (size < st.length()) {

					if (list.size() > 0) {
						list.remove(list.size()-1);
					}
					size = st.length();
					list.add(st);
				}
			}
			builder = new StringBuilder();
		}
		System.out.println(list);
	}
}

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Java program to print the output like- input will be "a4k3b2" and output should be after 'a' 4th character, after 'k' 3rd character and the final output : "aeknbd"

public class StringTest {

    public static void main(String[] args) {

        String str = "a4k3b2";// output aeknbd


        System.out.println(replaceChar(str));;
    }

    private static StringBuilder replaceChar(String str) {

        StringBuilder stB = new StringBuilder();

        char[] c = str.toCharArray();

        for (int i = 0; i < c.length; i++) {
            char cha = c[i];
            
            if(Character.isAlphabetic(c[i])) {
                stB.append(cha);
            }else{
                
                int v = c[i-1];
                char value = c[i];
                char digitChar = (char) (v + (value-48));
                stB.append(digitChar);
            }
        }
        return stB;

    }
}

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Sample Questions: Java Test

 Please read all the questions and select the correct option in the form below. 

 1. Given the code fragment:

    public class App {
      void calcBill() {
        // Line n1
        new Invoice().print();
      }
    }

    Which code fragment can be inserted at Line n1 to enable the class compile?
    A) private class Invoice {
         void print() {System.out.println("Invoice Printed");}
       }
    B) public class Invoice {
         void print() {System.out.println("Invoice Printed");}
       }
    C) class Invoice {
         void print() {System.out.println("Invoice Printed");}
       }
    D) protected class Invoice {
         void print() {System.out.println("Invoice Printed");}
       }


 2. Given:

    public interface MyInt {
      public void method1() {
        System.out.println("method1");
      }
      public default void method2() {
        System.out.println("method2");
      }
      public static void method3() {
        System.out.println("method3");
      }
      public abstract void method4();
    }

    Which statement is true?
    A) Only method4() compiles
    B) Only method2() and method4() compiles.
    C) Only method2(), method3(), and method4() compiles.
    D) MyInt.java compiles.



 3. Given the code fragment:

    public static void main(String[] args) {
      List courses = Arrays.asList("Java", "Oracle", "JSF", "EJB");
      // Line n1
      System.out.println(count);
    }

    Which code fragment can be inserted at Line n1 to enable the code to print 2?
    A) int count = courses.stream().filter(s -> s.startsWith("J")).count();
    B) long count = courses.stream().filter(s -> s.startsWith("J")).count();
    C) int count = courses.filter(s -> s.startsWith("J")).stream().count();
    D) long count = courses.filter(s -> s.startsWith("J")).stream().count();


 3. Given the code fragment:

    public static void main(String[] args) {
      List courses = Arrays.asList("Java", "Oracle", "JSF", "EJB");
      // Line n1
      System.out.println(count);
    }

    Which code fragment can be inserted at Line n1 to enable the code to print 2?
    A) int count = courses.stream().filter(s -> s.startsWith("J")).count();
    B) long count = courses.stream().filter(s -> s.startsWith("J")).count();
    C) int count = courses.filter(s -> s.startsWith("J")).stream().count();
    D) long count = courses.filter(s -> s.startsWith("J")).stream().count();


 4. Given the code fragment:

    public class App{
      public static void main(String[] args) {
        String[] fruits = {"banana", "apple", "pears", "grapes"};
        Arrays.sort(fruits, (a, b) -> a.compareTo(b));
        for (String s : fruits) {
          System.out.print(" "+s);
        }
      }
    }

    What is the result?
    A) apple banana grapes pears
    B) pears grapes banana apple
    C) banana apple pears grapes
    D) Compilation fails.


 5. Given the code fragment:

    LocalDate date1 = LocalDate.of(2016, Month.JANUARY, 1);
    LocalDateTime date2 = LocalDateTime.of(2017, Month.JUNE, 1, 1, 1);
    Period p = Period.between(date1, date2);
    System.out.print(p.getYears() + ":" + p.getMonths() + ":" + p.getDays());

    What is the result?
    A) 1:5:0
    B) 1:6:0
    C) 0:0:0
    D) Compilation fails.


 6. Given that /report/jun.txt and report/data/jundata.txt files are accessible
and given the code fragment:

    public static void main(String[] args) {
      try (Stream st1 = Files.find(Paths.get("/report"), 2, (p, a) ->
      p.toString().endsWith("txt"));
      Stream st2 = Files.walk(Paths.get("/report"), 2);) {
        st1.forEach(s -> System.out.println("Found: " + s));
        st2.filter(s -> s.toString()
        .endsWith("txt"))
        .forEach(s -> System.out.println("Walked: " + s));
      } catch (IOException ioe) {
            System.out.println("Exception");
        }
    }

    What is the result?
    A) Found: \report\data\jundata.txt
       Found: \report\jun.txt
       Walked: \report\data\jundata.txt
       Walked: \report\jun.txt
    B) Found: \report\data\jundata.txt
       Found: \report\jun.txt
       Walked: \report\data\jundata.txt
       Walked: \report
       Walked: \report\jun.txt
       Walked: \report\data\
    C) Found: \report\jun.txt
       Walked: \report\data\jundata.txt
       Walked: \report\jun.txt
    D) Found: \report\jun.txt
       Walked: \report
       Walked: \report\jun.txt
       Walked: \report\data\
       Walked: \report\data\jundata.txt


 7. Given the code fragment:

    public static void main(String[] args) {
      Stream nums = Stream.of(1, 2, 3, 4, 5);
      nums.filter(n -> n % 2 == 1);
      nums.forEach(p -> System.out.print(p));
    }

    What is the result?
    A) 135
    B) 12345
    C) Compilation fails.
    D) An exception is thrown at runtime.


 8. Given the code fragment:

   class MyResource1 implements Closeable {
     public void close() {
       System.out.print("r1 ");
     }
   }
   class MyResource2 implements AutoCloseable {
     public void close() throws IOException {
       System.out.print("r2 ");
       throw new IOException();
     }
   }
   public class App2 {
     public static void main(String[] args) {
       try (MyResource1 r1 = new MyResource1(); 
              MyResource2 r2 = new MyResource2();) {
           System.out.print("try ");
       } catch (Exception e) {
           System.out.print("catch ");
           for (Throwable t : e.getSuppressed()) {
             System.out.println(t.getClass().getName());
           }
         }
     }
   }
    What is the result?
    A) try r2 r1 catch java.io.IOException
    B) try r2 r1 catch
    C) try r1 r2 catch
    D) Compilation fails.

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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);
      }
  });
 }
}

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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);



 }

}

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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);
     }
}

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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);
 }
}

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