Core Java - Interview Questions and Answers for 'Collectors' | Search Interview Question

Core Java - Interview Questions and Answers for 'Collectors' - 6 question(s) found - Order By Newest

Q1. Write a Program that gets a set of numbers , filters out the non prime numbers , calculate the factorial of each prime number and then finds the average of all factorials using Lambda expressions

Ans. public class BuggyBread1 {

   public static void main(String args[]) {

      // Declare and Initialize the Collection
      Set<Integer> intSet = new HashSet<Integer>();

      // Add Elements
      intSet.add(1);
      intSet.add(2);
      intSet.add(3);
      intSet.add(4);
      intSet.add(5);

      double averageOfNonPrimeFactorials = intSet.stream().filter(p->checkIfPrime(p)).collect(Collectors.averagingInt(p->calculateFactorial(p)));

      System.out.println(averageOfNonPrimeFactorials );
   }

   static private boolean checkIfPrime(int num){
      for(int count=2;count < num;count++){
         if(num % count == 0){
            return false;
         }
      }
      return true;
   }

   static private int calculateFactorial(int num){
      int factorial = 1;
      for(int count=num;count > 0;count--){
         factorial = factorial * count;
      }
      return factorial;
   }
}

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Q2. Write a class / program that takes few numbers from the input and then output the average ?

Core Java

Ans. public class Class{
   public static void main(String[] args){
      List<Integer> collector = new ArrayList();

      Scanner scanner = new Scanner(System.in);
      int x = scanner.nextInt();
      while(x != 0){
         collector.add(x);
         x = scanner.nextInt();
      }
      System.out.println(collector.stream().collect(Collectors.averagingInt(p->((Integer)p))));
   }
}

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Q3. What are we doing here

list.stream().collect(Collectors.groupingBy(ClassA::getElement1,
Collectors.averagingDouble(ClassA::getelement2)));

Core Java

Ans. We are averaging elements of a collection by element1 grouped by element1

* list is the reference of collection
* element1 is the member element returned by getElement1 method of ClassA
* element2 is the member element returned by getElement2 method of ClassA

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Q4. Write code to get count of every 5 letter word in a string using lambda expression

Core Java

Ans. String str = "I had been saying that he had been there";

Map<String,Long> countWords = Arrays.asList(str.split(" ")).stream().filter(p->p.length() = 5).collect(Collectors.groupingBy(p->p,Collectors.counting()));

System.out.println(countWords);

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Q5. Can you explain filter and collectors in java 8 ?

Core Java

^{This question is still unanswered. Can you please provide an answer.}

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Q6. Can you explain filter and collectors in java 8 ?

Core Java

^{This question is still unanswered. Can you please provide an answer.}

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