Filter a Map by Keys and Values using Java Stream
Learn to filter a Map by keys or values or both, using the Java 8 Stream filter() and collect() methods with examples.
Java Streams are a powerful feature introduced in Java 8 for processing sequences of data in a functional and declarative style. They provide a high-level abstraction over collections, arrays, and other data sources, enabling concise and expressive operations on data.
Java Streams are part of the java.util.stream package and are designed to work seamlessly with lambda expressions, which were also introduced in Java 8.
Related Tags
Tutorials
Java Stream contains, containsAny and containsAll Examples
Learn to create a Java Stream utility class with contains(), containsAll() or containsAny() methods and learn to use them with examples.
Filter Nested Collections with Stream in Java
Java Stream API provides excellent filtering capability on the elements in the Stream. Sometimes, the stream elements also contain the nested collections; we need to filter those elements in the nested collections. This Java tutorial discusses various approaches with examples to apply filtering on nested collections and collecting the filtered …
Java Stream mapMulti() Example
Stream mapMulti() is a specialized form of the map() method that transforms each element of a stream into one or multiple output elements or none at all.
Handle Exceptions Thrown in Java Streams
Learn to handle the checked exceptions thrown from the methods used in Stream operations in Java 8 using safe method extraction and Optional.
Java 8 Stream – Collectors GroupingBy with Examples
Learn to use Collectors.groupingBy() method to group and aggregate the Stream elements similar to ‘GROUP BY‘ clause in the SQL. Stream -> groupingBy() -> Map of elements after applying ‘group by’ operation 1. Collectors.groupingBy() Method 1.1. Syntax The groupingBy() method returns a Collector implementing a “GROUP BY” operation on Stream …
[Solved] “Stream has already been operated upon or closed” Exception
Learned the root cause and solution of the Java Stream exception “IllegalStateException: stream has already been operated upon or closed”.
How to Iterate Over a Stream With Indices
Java Streams have gained a lot of awareness and being able to iterate through with indices can be helpful. Learn a few ways with examples.
Java – Remove/Update Elements From List using Stream
Learn to remove and update elements of a Collection using Stream.filter() and Strea,map() methods in Java with examples.
How to Filter a Map by List of Keys in Java
Learn to filter a Java HashMap by List of keys and collect the matching entries into a submap or matching values in a List.
How To Debug Java Streams
Debugging Java streams can be challenging. In this post, learn to debug streams as their elements are processed in the chained method calls.
Java Stream Tutorials
This Java tutorial lists down the published tutorials on this blog related to Stream API, methods and its related concepts with examples.
Primitive Type Streams in Java
Learn to create and operate on the streams of primitive types (IntStream, LongStream and DoubleStream) in Java with examples.
Generic Functional Interfaces in Java
Learn to create generic functional interfaces with and without type restrictions in Java. Learn to create specialized functional interfaces.
Creating Streams in Java
Learn to create Streams of primitives and objects in Java using some most popular ways. We will learn to create finite as well as infinite streams.
Java Stream API: Real-world Examples for Beginners
Java Streams can be defined as a sequence of elements from a source that supports aggregate operations on them. The source refers to a collection or array.
Functional Interfaces in Java
Introduced in Java 8, a functional interface is simply an interface that has exactly one abstract method. Learn more about functional interfaces in this tutorial.