Author: Editorial Team
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Collectors.groupingBy
Collectors.groupingBy is a powerful collector in Java Streams used to group elements of a stream based on a classifier function. It is commonly used for aggregation tasks like counting, summing, or finding max/min per group. 1. Basic Concept Collectors.groupingBy groups stream elements based on a classifier function: 2. Example 1: Group Strings by Length Output:…
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Create a Map of Department to Highest-Paid Employee Using Streams
When working with a list of employees, a common requirement is to find the highest-paid employee in each department. Java Streams provide concise ways to do this using groupingBy and maxBy. Assume the following Employee class: And a list of employees: Approach 1: Using groupingBy + maxBy (Optional Result) Explanation: Approach 2: Using collectingAndThen to…
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Find Difference Between Two Lists Using Java Streams
Assume two lists: Elements in list1 but not in list2 Output: Summary:
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Find Difference Between Two Lists Using Java Streams
Assume two lists: Elements in list1 but not in list2 Output: Summary:
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Find Union of Two Lists Using Java Streams
Assume two lists: Using Stream.concat() + distinct() Output: Summary:
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Find Intersection of Two Lists Using Java Streams
Assume two lists: Using filter() and collect() Output:
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Find Maximum Element Using reduce() in Java
Assume a list of integers: Using reduce() Output: Summary: This is a functional alternative to Collections.max() or stream().max().
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Generate Fibonacci Numbers Using Java Streams
Approach 1: Using Stream.iterate() Generate the first n Fibonacci numbers: Output: Explanation: This approach is functional, lazy, and efficient for generating Fibonacci numbers with Java Streams.
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Get Prime Numbers from a List Using Java Streams
Assume a list of integers: Approach: Using filter() with a Prime Check Output: Summary: This approach works efficiently for small to moderate-sized lists of integers.