java 8 streams

Optional Class

The Optional class in Java, introduced in Java 8, is designed to address the problem of null references. It represents an object that may or may not contain a non-null value. This class encourages explicit handling of null values, reducing the likelihood of NullPointerExceptions and making code more robust and readable. The Optional class has …

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Numerical Streams and Special Stream Operations

Numerical streams in Java, part of the Stream API introduced in Java 8, are specialized streams for handling primitive numeric types (int, long, double) to avoid the overhead of boxing/unboxing in regular object streams. They include IntStream, LongStream, and DoubleStream, found in the java.util.stream package. These streams are optimized for numerical computations and provide specific …

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Lazy Evaluation and Short-Circuiting Operations

In Java 8 Streams, lazy evaluation and short-circuiting operations are key features that optimize performance by processing only the necessary data. Below, I explain both concepts, their mechanisms, and examples. Lazy Evaluation Lazy evaluation means that intermediate operations in a stream pipeline are not executed until a terminal operation is invoked. Each intermediate operation (e.g., …

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Partitioning Operations

In Java 8 Streams, partitioning is a way to split a stream’s elements into two groups based on a predicate (a condition that returns true or false). This is achieved using the Collectors.partitioningBy collector, which groups elements into a Map<Boolean, List<T>>, where the keys are true (elements matching the predicate) and false (elements not matching …

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Grouping Operations

In Java, grouping operations with the Stream API are powerful for organizing data into categories, typically using the Collectors.groupingBy collector. These operations allow you to group stream elements based on a classification function, similar to SQL’s GROUP BY. The result is often a Map where keys are categories and values are collections of elements (or …

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The Collector interface

The Collector interface in Java, part of the java.util.stream package, defines how elements of a Stream are collected into a final result, such as a List, Set, Map, or other data structure. It’s used with the Stream.collect() method and is highly flexible, allowing both predefined collectors (via Collectors class) and custom implementations. Below, I’ll explain …

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Reducing Operations

Reducing operations in Java Streams are used to combine elements of a stream into a single result using an associative accumulation function. These operations are also known as fold operations because they repeatedly apply a binary operator to the elements, progressively reducing them to a single value. 1. reduce() Method The reduce() method performs a …

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