#Java - Code Snippets for '#Collector'

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

Sample 1. 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 2. 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 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

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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}

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. 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 7. 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}

Sample 8. 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 9. 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}

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Sample 10. 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);

  }

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Sample 11. 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));

  }

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