Share

Search Java Code Snippets


  Help us in improving the repository. Add new snippets through 'Submit Code Snippet ' link.





#Java - Code Snippets for '#Collectors' - 11 code snippet(s) found

 Sample 1. Combine two Summaries and Generate a new Summary using Lambda Expression

// Populate a List using Set elements.

// Declare and Initialize the Collection

Set<Integer> intSet = new HashSet<Integer>();
Set<Integer> intSet2 = new HashSet<Integer>();

// Add Elements

intSet.add(1);
intSet.add(2);
intSet.add(3);
intSet.add(4);
intSet2.add(1);
intSet2.add(2);
intSet2.add(3);
intSet2.add(4);

// Use the stream and collectors to Summarize all Integer elements

IntSummaryStatistics summary = intSet.stream().collect(Collectors.summarizingInt(p->((Integer)p)));

summary.combine(intSet2.stream().collect(Collectors.summarizingInt(p->((Integer)p))));

System.out.println(summary); // Prints IntSummaryStatistics{count=8, sum=20, min=1, average=2.500000, max=4}

   Like      Feedback     lambda expression   collections   set  hashset  generics  stream   collectors   Collectors.summarizingInt   summary.combine  java.util.hashset  java.util.stream.Collectors  java.util.IntSummaryStatistics


 Sample 2. Get all elements greater than 2, sort them and then push them to a new set, using Lambda Expression

// 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);

// Set the predicate or the condition for filtering the elements.

Predicate<Integer> moreThan2Pred = (p) -> (p > 1);

// Use Filter to refine the element set, sort to Sort and Collectors.toSet to get a set out of Stream.

intSet = intSet.stream().filter(moreThan2Pred).sorted().collect(Collectors.toSet());

System.out.println(intSet); // Prints [2, 3, 4]

   Like      Feedback     lambda expression   collections   set  hashset  generics  stream   predicate   filter   sort  java.util.hashset  java.util.stream.Collectors


 Sample 3. Find the Average of all collection elements using Lambda Expressions

// 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);

// Use the stream and Collector to find the average of all elements.

System.out.println(intSet.stream().collect(Collectors.averagingInt(p->((Integer)p))));  Prints 2.5

   Like      Feedback     lambda expression   collections   set  hashset  generics  stream   collector


 Sample 4. Group Elements by even or Odd using Lambda Expressions

// 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);

// Use the stream and Collector to Group by Even and Odd

System.out.println(intSet.stream().collect(Collectors.groupingBy(p->((Integer)p)%2)));  Prints {0=[2, 4], 1=[1, 3]}

   Like      Feedback     lambda expression   collections   set  hashset  generics  stream   collectors   Collectors.groupingBy


Subscribe to Java News and Posts. Get latest updates and posts on Java from Buggybread.com
Enter your email address:
Delivered by FeedBurner
 Sample 5. Sum all collection elements using Lambda Expressions

// 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);

// Use the stream and collectors to sum all elements.

System.out.println(intSet.stream().collect(Collectors.summingInt(p->(Integer)p)));

   Like      Feedback     lambda expression   collections   set  hashset  generics  stream   collectors   Collectors.groupingBy


 Sample 6. Populate a List using Set elements and Lambda Expression

// 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);

// Use the stream and collectors to get List out of Set

List li = intSet.stream().collect(Collectors.toList());
System.out.println(li); // Prints [1, 2, 3, 4]

   Like      Feedback     lambda expression   collections   set  hashset  generics  stream   collectors   Collectors.toList


 Sample 7. Get the complete Summary of Collection Elements using Lambda Expressions

// Populate a List using Set elements.

// 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);

// Use the stream and collectors to Summarize all Integer elements 

System.out.println(intSet.stream().collect(Collectors.summarizingInt(p->((Integer)p)))); // Prints IntSummaryStatistics{count=4, sum=10, min=1, average=2.500000, max=4}

   Like      Feedback     lambda expression   collections   set  hashset  generics  stream   collectors   Collectors.summarizingInt


 Sample 8. Create a Map using Set elements using Lambda Expression

// 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);

// Use the stream and collectors to get a Map out of Set 

System.out.println(intSet.stream().collect((Collectors.toMap(p->(Integer)p,q->((Integer)q)*500)))); // Prints {1=500, 2=1000, 3=1500, 4=2000} 

   Like      Feedback     lambda expression   collections   set  hashset  generics  stream   collectors


 Sample 9. Code Sample / Example / Snippet of org.apache.storm.task.OutputCollector

  public void shouldEmitNothingIfNoObjectHasBeenCountedYetAndTickTupleIsReceived() {

Tuple tickTuple = MockTupleHelpers.mockTickTuple();

RollingCountBolt bolt = new RollingCountBolt();

Map conf = mock(Map.class);

TopologyContext context = mock(TopologyContext.class);

OutputCollector collector = mock(OutputCollector.class);

bolt.prepare(conf, context, collector);



bolt.execute(tickTuple);



verifyZeroInteractions(collector);

}


   Like      Feedback      org.apache.storm.task.OutputCollector


Subscribe to Java News and Posts. Get latest updates and posts on Java from Buggybread.com
Enter your email address:
Delivered by FeedBurner
 Sample 10. Code Sample / Example / Snippet of org.apache.storm.topology.BasicOutputCollector

  public void shouldEmitSomethingIfTickTupleIsReceived() {

Tuple tickTuple = MockTupleHelpers.mockTickTuple();

BasicOutputCollector collector = mock(BasicOutputCollector.class);

TotalRankingsBolt bolt = new TotalRankingsBolt();



bolt.execute(tickTuple, collector);



verify(collector).emit(any(Values.class));

}


   Like      Feedback      org.apache.storm.topology.BasicOutputCollector


 Sample 11. 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

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;
   }
}

   Like      Feedback     java 8  lambda expressions  lambda  filter  Collectors  factorial  prime number



Subscribe to Java News and Posts. Get latest updates and posts on Java from Buggybread.com
Enter your email address:
Delivered by FeedBurner



comments powered by Disqus