Intermediate Operations: filter(), map(), flatMap(), sorted(), distinct()0%

Terminal Operations: collect(), forEach(), reduce(), count(), anyMatch()

Intermediate Operations: filter(), map(), flatMap(), sorted(), distinct()

Advanced16 min read•Updated: 2025-01-15

⚙️ Intermediate Operations: filter(), map(), flatMap(), sorted(), distinct()

Introduction

Intermediate operations return a new Stream<T>. Because they return a stream, they can be chained into an expressive transformation pipeline. They are stateless or stateful, and always lazy.

🛠️ Detailed Breakdown of Core Operations

1. `filter(Predicate<T>)`

Discards elements that do not satisfy the condition:

1List<Integer> scores = List.of(45, 82, 91, 38, 77);
2scores.stream()
3      .filter(s -> s >= 75) // Keeps only scores >= 75
4      .forEach(System.out::println); // Output: 82, 91, 77

2. `map(Function<T, R>)`

Transforms each element 1-to-1 into another representation:

1List<String> cities = List.of("Delhi", "Agra", "Shikohabad");
2List<Integer> lengths = cities.stream()
3                              .map(String::length)
4                              .toList(); // [5, 4, 10]

3. `flatMap(Function<T, Stream<R>>)`

Flattens multiple nested collections or streams (1-to-N) into a single unified stream:

1List<List<String>> courseModules = List.of(
2    List.of("Variables", "Operators"),
3    List.of("Classes", "Objects"),
4    List.of("Threads", "Generics")
5);
6 
7// Flatten into 1 flat stream:
8List<String> allTopics = courseModules.stream()
9                                      .flatMap(List::stream)
10                                      .toList();
11System.out.println(allTopics); 
12// [Variables, Operators, Classes, Objects, Threads, Generics]

4. `distinct()` & `sorted()`

1List<Integer> duplicates = List.of(5, 2, 9, 2, 5, 1);
2duplicates.stream()
3          .distinct()                   // Removes duplicates
4          .sorted()                     // Natural sorting (1, 2, 5, 9)
5          .forEach(System.out::println);

5. `limit(n)` & `skip(n)`

Used for stream pagination:

1List<String> page2 = allTopics.stream()
                            .skip(2)  // Skip first 2 items
                            .limit(2) // Take next 2 items
                            .toList();

Next Lesson

Terminal Operations: collect(), forEach(), reduce(), count(), anyMatch()

Continue learning with hands-on practice, examples, and exercises in the upcoming topic.

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Stream Pipeline Lifecycle: Source -> Intermediate Operations -> Terminal Operation	Terminal Operations: collect(), forEach(), reduce(), count(), anyMatch()

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Terminal Operations: collect(), forEach(), reduce(), count(), anyMatch()

Intermediate Operations: filter(), map(), flatMap(), sorted(), distinct()

Advanced16 min read•Updated: 2025-01-15

Study Materials

⚙️ Intermediate Operations: filter(), map(), flatMap(), sorted(), distinct()

Introduction

Intermediate operations return a new Stream<T>. Because they return a stream, they can be chained into an expressive transformation pipeline. They are stateless or stateful, and always lazy.

🛠️ Detailed Breakdown of Core Operations

1. `filter(Predicate<T>)`

Discards elements that do not satisfy the condition:

1List<Integer> scores = List.of(45, 82, 91, 38, 77);
2scores.stream()
3      .filter(s -> s >= 75) // Keeps only scores >= 75
4      .forEach(System.out::println); // Output: 82, 91, 77

2. `map(Function<T, R>)`

Transforms each element 1-to-1 into another representation:

1List<String> cities = List.of("Delhi", "Agra", "Shikohabad");
2List<Integer> lengths = cities.stream()
3                              .map(String::length)
4                              .toList(); // [5, 4, 10]

3. `flatMap(Function<T, Stream<R>>)`

Flattens multiple nested collections or streams (1-to-N) into a single unified stream:

1List<List<String>> courseModules = List.of(
2    List.of("Variables", "Operators"),
3    List.of("Classes", "Objects"),
4    List.of("Threads", "Generics")
5);
6 
7// Flatten into 1 flat stream:
8List<String> allTopics = courseModules.stream()
9                                      .flatMap(List::stream)
10                                      .toList();
11System.out.println(allTopics); 
12// [Variables, Operators, Classes, Objects, Threads, Generics]

4. `distinct()` & `sorted()`

1List<Integer> duplicates = List.of(5, 2, 9, 2, 5, 1);
2duplicates.stream()
3          .distinct()                   // Removes duplicates
4          .sorted()                     // Natural sorting (1, 2, 5, 9)
5          .forEach(System.out::println);

5. `limit(n)` & `skip(n)`

Used for stream pagination:

1List<String> page2 = allTopics.stream()
                            .skip(2)  // Skip first 2 items
                            .limit(2) // Take next 2 items
                            .toList();

Next Lesson

Terminal Operations: collect(), forEach(), reduce(), count(), anyMatch()

Continue learning with hands-on practice, examples, and exercises in the upcoming topic.

Related Lessons

Previous Lesson	Next Lesson
Stream Pipeline Lifecycle: Source -> Intermediate Operations -> Terminal Operation	Terminal Operations: collect(), forEach(), reduce(), count(), anyMatch()

Practice Quiz

Test your understanding of this lesson with 1 questions. Each question has one correct answer.

Previous Next

⚙️ Intermediate Operations: filter(), map(), flatMap(), sorted(), distinct()

Introduction

🛠️ Detailed Breakdown of Core Operations

1. filter(Predicate<T>)

2. map(Function<T, R>)

3. flatMap(Function<T, Stream<R>>)

4. distinct() & sorted()

5. limit(n) & skip(n)

Terminal Operations: collect(), forEach(), reduce(), count(), anyMatch()

Related Lessons

Practice Quiz

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⚙️ Intermediate Operations: filter(), map(), flatMap(), sorted(), distinct()

Introduction

🛠️ Detailed Breakdown of Core Operations

1. filter(Predicate<T>)

2. map(Function<T, R>)

3. flatMap(Function<T, Stream<R>>)

4. distinct() & sorted()

5. limit(n) & skip(n)

Terminal Operations: collect(), forEach(), reduce(), count(), anyMatch()

Related Lessons

Practice Quiz

1. `filter(Predicate<T>)`

2. `map(Function<T, R>)`

3. `flatMap(Function<T, Stream<R>>)`

4. `distinct()` & `sorted()`

5. `limit(n)` & `skip(n)`

1. `filter(Predicate<T>)`

2. `map(Function<T, R>)`

3. `flatMap(Function<T, Stream<R>>)`

4. `distinct()` & `sorted()`

5. `limit(n)` & `skip(n)`