Core Java - Interview Questions and Answers for 'Core Java' | Search Interview Question - javasearch.buggybread.com

Javasearch.buggybread.com

Search Interview Questions

More than 3000 questions in repository.

There are more than 900 unanswered questions.
Click here and help us by providing the answer.

Have a video suggestion.
Click Correct / Improve and please let us know.

Submit Question

Interview Questions and Answers - Order By Newest

next 30

Q641. Write a Program to print duplicate words in a String

Ans. public class BuggyBread {
public static void main(String args[]) {
String str = "we are what we repeatedly Do excellence, then, is not an act but a haBit";
Set<String> words = new HashSet();
for(String word:str.split(" ")){
if(words.contains(word)){
System.out.println(word);
} else {
words.add(word);
}
}
}
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve Asked in 1 Companies}

Q642. Write a Program to print words of a String starting with character w

Ans. public class BuggyBread {
   public static void main(String args[]) {
       String str = "we are what we repeatedly Do excellence, then, is not an act but a haBit";
       for(String word:str.split(" ")){
          if(word.startsWith("w")){
             System.out.println(word);
          }
       }
   }
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve}

Q643. Write a Program to print words of a String containing the specified String.

For example - Print all words having characters ha

Ans. public class BuggyBread {
   public static void main(String args[]) {
       String str = "we are what we repeatedly Do excellence, then, is not an act but a haBit";
       for(String word:str.split(" ")){
          if(word.contains("ha")){
             System.out.println(word);
          }
       }
   }
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve}

Q644. Write a Program to print words in a string having length greater than 2 and third characters being p

Ans. public class BuggyBread {
   public static void main(String args[]) {
       String str = "we are what we repeatedly Do excellence, then, is not an act but a haBit";
       for(String word:str.split(" ")){
          if(word.length() > 2 && word.charAt(2) == 'p'){
             System.out.println(word);
          }
       }
   }
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve}

Q645. Write a Program to print words of a String having length greater than 2 and ending with it

Ans. public class BuggyBread {
   public static void main(String args[]) {
       String str = "we are what we repeatedly Do excellence, then, is not an act but a haBit";
       for(String word:str.split(" ")){
          if(word.length() > 2 && word.endsWith("it")){
             System.out.println(word);
          }
       }
   }
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve}

Q646. Write code to find second largest number in an array of integers.

Ans. int arr[]={1,3,5,6,4,8,9,2,10};
Arrays.sort();
System.out.println(arr[arr.length-1]);

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve code coding find in array Asked in 1 Companies}

Q647. Write a Program to find common words in 2 separate strings

Ans. public class BuggyBread {
   public static void main(String args[]) {
       String str1 = "we are what we repeatedly Do excellence, then, is not an act but a haBit";
       String str2 = "we are what we repeatedly Do is";
       String[] str1Words = str1.split(" ");
       String[] str2Words = str2.split(" ");

       Set str1WordsSet = new HashSet();

       for(String word:str1Words){
          str1WordsSet.add(word);
       }

       for(String word:str2Words){
          if(str1WordsSet.contains(word)){
             System.out.println(word);
          }
       }

   }
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve String coding code}

Q648. Write a program to print count / no of common words in 2 separate strings

Ans. public class BuggyBread {
   public static void main(String args[]) {
       String str1 = "we are what we repeatedly Do excellence, then, is not an act but a haBit";
       String str2 = "we are what we repeatedly Do is";
       String[] str1Words = str1.split(" ");
       String[] str2Words = str2.split(" ");

       Set str1WordsSet = new HashSet();

       for(String word:str1Words){
          str1WordsSet.add(word);
       }

       int commonWordsCount = 0;

       for(String word:str2Words){
          if(str1WordsSet.contains(word)){
             commonWordsCount++;
          }
       }

       System.out.println(commonWordsCount);
   }
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve String coding code}

Q649. Write a Program to remove duplicate words from the String

Ans.
public class BuggyBread {
public static void main(String args[]) {
String str = "we are what we repeatedly Do excellence, then, is not an act but a haBit";
Set<String> wordSet = new LinkedHashSet(); // Using Linked Hash Set as we would like to retrieve words in the insertion order

for(String word: str.split(" ")){
wordSet.add(word);
}

for(String word: wordSet){
System.out.print(word);
System.out.print(" ");
}
}
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve String coding code Asked in 1 Companies basic}

Q650. Write a Program to display the words of a String in alpahbetical or Dictionary Order

Ans. public class BuggyBread {
   public static void main(String args[]) {
       String str = "we are what we repeatedly do excellence then is not an act but a haBit";
       Set<String> wordSet = new TreeSet(); // Using Linked Hash Set as we would like to retrieve words in the insertion order

       for(String word: str.split(" ")){
          wordSet.add(word);
       }

       for(String word: wordSet){
          System.out.print(word);
          System.out.print(" ");
       }
   }
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve String coding code}

Q651. Write a program to print sum of numbers between the start and end number

For example - Passing start number as 2 and end number as 10, it should print 2+3+4+5+6+7+8+9+10 = 54

Ans.
public class BuggyBread {
   public static void main(String args[]) {
       System.out.println(sum(2,10));
   }

   private static int sum(int start,int end){
      if(start > end){
         return 0;
      } else {
         return start + sum(start+1,end);
      }
   }
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve recursion}

Q652. Write a program using Recursion to print multiplication of numbers between the start and end number

For example - Passing start number as 2 and end number as 10, it should print 2*3*4*5*6*7*8*9*10 = 3628800

Ans.
public class BuggyBread {
   public static void main(String args[]) {
       System.out.println(multiply(2,5));
   }

   private static int multiply(int start,int end){
      if(start > end){
         return 1;
      } else {
         return start * multiply(start+1,end);
      }
   }
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve recursion}

Q653. Write a Program to display numbers between 2 numbers using recursion

Ans. public class BuggyBread {
   public static void main(String args[]) {
       displayNumbersBetween(2,10);
   }

   private static void displayNumbersBetween(int start,int end){
      if(start > end){
         return ;
      } else {
         System.out.println(start);
         displayNumbersBetween(start+1,end);
      }
   }
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve recursion code coding}

Q654. Write a Program to print asterix like following using Recursion

**
***
****
*****
******
*******
********
*********
**********

Program should set the start and end index and then display this accordingly. For example the above pattern is for displayNumbersBetween(2,10) and following is for displayNumbersBetween(5,7)

*****
******
*******

Ans. public class BuggyBread {
   public static void main(String args[]) {
       displayNumbersBetween(5,7);
   }

   private static void displayNumbersBetween(int start,int end){
      if(start > end){
         return ;
      } else {
         for(int x=1;x<=start;x++){
            System.out.print("*");
         }
         System.out.println("");
         displayNumbersBetween(start+1,end);
      }
   }
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve recursion code coding}

Q655. Write a Program to print pattern like following

*
**
***
****
*****
******
*******
********
*********
**********

Ans. public class BuggyBread {
   public static void main(String args[]) {
      for(int x=1;x<=10;x++){
         for(int y=1;y<=x;y++){
            System.out.print("*");
         }

         System.out.println("");
      }
   }
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve coding code}

Q656. Write a Program to print pattern like following

*_**_***_****_*****_***************

Ans. public class BuggyBread {
   public static void main(String args[]) {
      for(int x=1;x<=5;x++){
         for(int y=1;y<=x;y++){
            System.out.print("*");
         }

         System.out.print("_");
      }

      for(int x=5;x>=1;x--){
         for(int y=1;y<=x;y++){
            System.out.print("*");
         }

         System.out.print("");
      }
   }
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve}

Q657. Write a Program to print numbers like following

1
12
123
1234
12345

Ans. public class BuggyBread {
   public static void main(String args[]) {
      for(int x=1;x<=5;x++){
         for(int y=1;y<=x;y++){
            System.out.print(y);
         }

         System.out.println(" ");
      }
   }
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve}

Q658. Write a Program to print numbers like following

1
22
333
4444
55555

Ans. public class BuggyBread {
   public static void main(String args[]) {
      for(int x=1;x<=5;x++){
         for(int y=1;y<=x;y++){
            System.out.print(x);
         }

         System.out.println(" ");
      }
   }
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve}

Q659. Difference between concurrentHashMap and HashTable ?

Ans. HashTable locks the complete collection to provide synchronization whereas ConcurrentHashMap only locks segments to achieve synchronization and hence better efficient and faster.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve concurrentHashMap HashTable Map Collections Asked in 2 Companies}

Q660. isnt the use of HashTable and ConcurrentHashMap the same, i.e providing synchronized map collection ?

Ans. Yes, they both aim at providing synchronized access to the Map collection. The only difference is in their implementation. ConcurrentHashMap came after HashTable and hence technically more efficient as it doesn't lock the complete map while accessing it.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve HashTable ConcurrentHashMap map Collections}

Q661. Upon compiling the following class, What .class files will get created

public class OuterClass{
class InnerClass{
}
}

Ans. OuterClass.class AND OuterClass$InnerClass.class

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve class files compilation compile inner classes nested classes}

Q662. Write a Program to validate an email address

Ans. public class Class{
public static void main(String[] args){
String str = "xyz@123.com";

if(!str.contains("@") && !str.contains(".") && (str.indexOf('.') < str.indexOf('@'))){
System.out.println("Not a Valid Email Address");
}
}
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve validate an email address coding code Asked in 3 Companies}

Q663. Write a Program to validate if a particular character occurs after another in a string

Ans. public class Class{
   public static void main(String[] args){
      String str = "xyz123.co@m";

      if(str.indexOf('.') < str.indexOf('@')){
         System.out.println("Not a Valid Email Address");
      }
   }
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve string string.indexOf coding code}

Q664. Write a Program to find the missing integer in an array of consecutive numbers?

^{This question was recently asked at 'Knight Capital'.This question is still unanswered. Can you please provide an answer.}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve Asked in 1 Companies}

Q665. How to find the median number in an array of integers ?

Ans.

Arrays.sort(numArray);
double median;
if (numArray.length % 2 == 0)
median = ((double)numArray[numArray.length/2] (double)numArray[numArray.length/2 - 1])/2;
else
median = (double) numArray[numArray.length-1/2];

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve coding Asked in 2 Companies}

Q666. Write a Java program to print 10 random numbers between 1 to 100?

^{This question was recently asked at 'karya technology'.This question is still unanswered. Can you please provide an answer.}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve coding code Asked in 1 Companies}

Q667. Why don't Java objects have destructors ?

Ans. Java manages memory using built-in garbage collector

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve destructor garbage collection}

Q668. What is the difference between && and & in Java ?

Ans. && is a Logical whereas & is a bitwise operator

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve operators logical vs bitwise operator}

Q669. Why is it important to close files and streams ?

Ans. Optimizing Resource utilization. When you open a file using any programming language , that is actually a request to operating system to access the file. When such a request is made , resources are allocated by the OS. When you gracefully close those files, those resources are set free.

In Java if you don’t close the streams and files, Garbage collection identifies the open files which have lost the reference and hence will close them.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve file handling}

Q670. Write a method / program that will determine if the parenthesis are balanced in a given string.

Ans. https://www.geeksforgeeks.org/check-for-balanced-parentheses-in-an-expression/

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve string code coding Asked in 14 Companies}

previous 30

next 30