#Java - Code Snippets for '#Collectors.groupingBy'

#Java - Code Snippets for '#Collectors.groupingBy' - 3 code snippet(s) found

Sample 1. 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 2. 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)));

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Sample 3. Averaging Group By using Java 8

<Collection_Reference>.stream().collect(Collectors.groupingBy(<Class_Name>::<Method_to_get_group_by_element>,

               Collectors.averagingDouble(<Class_Name>::<Method_to_get_element_to_perform_averaging_on>)));



Example -



Get Dept and it's average Salary



list..stream().collect(Collectors.groupingBy(Employee::getDept,

               Collectors.averagingDouble(Employee::getSalary)));

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