#Java - Code Snippets for '#Lambda Expression'

#Java - Code Snippets for '#Lambda Expression' - 16 code snippet(s) found

Sample 1. Get count of elements greater than 1 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 Stream, Predicate and Filter to get the count of elements more than 1



System.out.println(intSet.stream().filter(moreThan2Pred).count()); // Prints 3

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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]

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Sample 3. Find, if all elements of a collection matches the specified condition ( Using Lambda expressions )

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// 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);



// Specify the Predicate or the Condition using Lambda expressions



Predicate<Integer> moreThan2Pred = (p) -> (p > 2); 



// Use the stream method allMatch to see if all elements fulfils the Predicate.

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Sample 4. 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 5. 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 6. Count number of 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 method count to see if all elements fulfils the Predicate.



System.out.println(intSet.stream().count); // Prints 4.

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Sample 7. 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]}

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Sample 8. 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 9. 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}

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Sample 10. Calculate square of a number using Lambda Expression

public interface Calc {

    int square(int value);

}



public static void main(String[] args){

    Calc calc = (int val) -> val * val;

    System.out.println(calc.square(5));

}

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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;

   }

}

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Sample 12. Find, if any element of the collection matches the specified condition ( Using Lambda Expressions )

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// 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);



// Specify the Predicate or the Condition using Lambda expressions



Predicate<Integer> moreThan2Pred = (p) -> (p > 2); 



// Use the stream method anyMatch to see if all elements fulfils the Predicate.



System.out.println(intSet.stream().anyMatch(moreThan2Pred)); // Prints True.

_{Like Feedback lambda expression collections set hashset generics predicate}

Sample 13. Find, if no element of the collection matches the specified condition ( Inverse of anyMatch )

// 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);



// Specify the Predicate or the Condition using Lambda expressions



Predicate<Integer> moreThan2Pred = (p) -> (p > 2); 



// Use the stream method noneMatch to see if all elements fulfils the Predicate.



System.out.println(intSet.stream().noneMatch(moreThan2Pred)); // Prints False.

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Sample 14. 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 15. 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 16. Get the Maximum number out of the Integer List, using Lambda Expression

// Declare and Initialize the Collection



List<Integer> intList = new ArrayList<Integer>();



// Add Elements



intList.add(1);

intList.add(2);

intList.add(3);

intList.add(4);





System.out.println(intList.stream().reduce(Math::max).get()); // Prints 1

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