Java Interview Questions - 4

In this tutorial we will see about few simple interview programming questions.

1. Sort 3 numbers without IF condition or looping.

public class Sort3No {
 public static void main(String[] args) {
  int x = 9;
  int y = 3;
  int z = 7;

  int first = Math.min(x, Math.min(y, z));
  int third = Math.max(x, Math.max(y, z));
  int second = x + y + z - first - third;

  System.out.println("SORTED NO's : " + first + ", " + second + ", "+ third);
 }
}

OUTPUT:

SORTED NO's : 3, 7, 9

2. Reverse the number without using String

public class ReverseNumber {
 
 public static void main(String[] args) {
  
  int number = 123456;

  int revNo = 0;
  while(number > 0){
   revNo = (10 * revNo) + (number % 10);
   number = number / 10;
  }
  
  System.out.println("REVERSED NO : "+revNo);
 }
}

OUTPUT:

REVERSED NO : 654321

3. Print first N Fibonacci numbers.

public class Fibonacci {

  public static void main(String[] args) { 
       int input = 10;
       int fib = 0,  val= 1;
       System.out.print("First "+input+" Fibonacci Numbers : ");
       for (int i = 0; i < input; i++) {
          fib = fib + val;
          val = fib - val;
          System.out.print(fib+", "); 
       }
  }
}

OUTPUT:

First 10 Fibonacci Numbers : 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 

4. Convert String to Date Object 

public class StringToDate {
 
 public static void main(String args[]) {
  try{
         String strDate = "23-5-2013";

         SimpleDateFormat format = new SimpleDateFormat("dd-MM-yyyy");
         Date date = format.parse(strDate);
         System.out.println("DATE : "+date);
  }catch (ParseException e) {
   e.printStackTrace();
  }
    }
}

OUTPUT:

DATE : Thu May 23 00:00:00 IST 2013

5. Find entered date is valid or not

public class ValidDate {

 public static void main(String[] args) {

  int day = 29;
  int month = 2;
  int year = 1984;

  int[] leapYearDays = { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
  int[] nonLeapYearDays = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

  if (month >= 1 && month <= 12) {
   if (year % 4 == 0) {
    if (day >= 1 && day <= leapYearDays[month - 1]) {
     System.out.println("Valid Date...");
    } else {
     System.out.println("Invalid Date");
    }
   } else {
    if (day >= 1 && day <= nonLeapYearDays[month - 1]) {
     System.out.println("Valid Date...");
    } else {
     System.out.println("Invalid Date");
    }
   }
  } else {
   System.out.println("Invalid Date");
  }
 }
}

OUTPUT:

Valid Date...

6. Find the day of week by given date.

public class DayOfWeek {

 public static void main(String[] args) {

  int day = 23;
  int month = 5;
  int year = 2013;

  String days[] = { "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" };

  int a = year - (14 - month) / 12;
  int x = a + a / 4 - a / 100 + a / 400;
  int b = month + 12 * ((14 - month) / 12) - 2;
  int c = (day + x + (31 * b) / 12) % 7;

  System.out.println(days[c]);
 }
}

OUTPUT:

Thursday

7. Print 5 random numbers between 2 numbers

public class PrintRandom {
 
 public static void main(String[] args) {
  
  int min = 100;
  int max = 200;
  
  for(int i=0;i<5;i++){
   int rand = new Random().nextInt(max);
   if(rand > min){
    System.out.println(rand);
   }else{
    i--;
   }
  }
 }
}

OUTPUT:

122
180
193
114
187

8. Replace character in a string without using Java API functions

public class ReplaceChar {

 public static void main(String[] args) {
  String str = "This document is the API specification for version 6 of the Java";
  System.out.println("INPUT              : "+str);
  str = replaceChar(str, 'Q', 'i'); // Change all 'i' to 'Q' 
  System.out.println("AFTER CHAR REPLACE : "+str);
 }
 
 public static String replaceChar(String str, char newChar, char oldChar){
  try{
   char[] charAry = str.toCharArray();
   for(int i=0;i<str.length();i++){
    if(charAry[i] == oldChar){
     charAry[i] = newChar;
    }
   }
   str = new String(charAry);
  }catch (Exception e) {
   e.printStackTrace();
  }
  return str;
 }
}

OUTPUT:

INPUT               : This document is the API specification for version 6 of the Java
AFTER CHAR REP: ThQs document Qs the API specQfQcatQon for versQon 6 of the Java

9. Write a Java program to find given number is odd or even without / or % operators. 

public class OddOrEven {
 
 public static void main(String[] args) {
  int no = 25;
  while(no>2){
   no -= 2;
  }
  if(no == 1){
   System.out.println("Given no. is Odd Number...");
  }else{
   System.out.println("Given no. is Even Number...");
  }
 }
}

OUTPUT:

Given no. is Odd Number...

10.  This is a simple mathematical calculation program. 
    
Example: Raj purchased the bag for Rs.2750 which includes 10% tax of bag price. So what will be the price of bag and tax amount?. Program should work for whatever be the amount as input.

public class CalculatePrice {
 
 public static void main(String[] args) {
  int price = 2750;
  float bagPrice = ((price/11f)*10f);
  float taxAmt = (price/11f);
  System.out.println("BAG PRICE   : "+bagPrice);
  System.out.println("TAX AMOUNT  : "+taxAmt);
  System.out.println("TOTAL PRICE : "+(bagPrice+taxAmt));
 }
}

OUTPUT:

BAG PRICE   : 2500.0
TAX AMOUNT  : 250.0
TOTAL PRICE : 2750.0