EASYTUTORGUIDEJava • Java 26

Streams

Chapter 31 of 60 • beginner to advanced • code example for every topic

5 topics5 code examples10 Q&A

31.1 Stream Concepts 31.2 Creating Pipelines 31.3 Filtering/Mapping 31.4 Collecting/Aggregating 31.5 Performance and Side Effects

31.1 Stream Concepts

This topic teaches Stream Concepts as part of Streams. Learn the purpose first, then inspect the syntax and test it with small inputs before using it in production.

Code example

import java.util.*;
public class Main { public static void main(String[] args){ var out=List.of(1,2,3,4,5,6).stream().filter(n->n%2==0).map(n->n*10).toList(); System.out.println(out); } }

Step-by-step explanation

Identify the values, objects, tables, or resources used by the example.
Read each statement in execution order.
Predict what the program or query should produce.
Run it in a safe local/test environment.
Change one input and explain the new result.

Expected output/result

You should see a small result that demonstrates Stream Concepts. Exact formatting can differ by runtime, client, database state, operating system, or tool version.

Common mistakes

Watch for invalid input, unchecked errors, incorrect type assumptions, missing cleanup, unsafe permissions, injection risks, or code/query logic that handles only the happy path.

Practice exercise

Rebuild this example with your own data. Add one edge case, predict the result before running it, and explain why the final result is correct.

31.2 Creating Pipelines

This topic teaches Creating Pipelines as part of Streams. Learn the purpose first, then inspect the syntax and test it with small inputs before using it in production.

Code example

public class Main { public static void main(String[] args) { // Creating Pipelines
System.out.println("Java example"); } }

Step-by-step explanation

Identify the values, objects, tables, or resources used by the example.
Read each statement in execution order.
Predict what the program or query should produce.
Run it in a safe local/test environment.
Change one input and explain the new result.

Expected output/result

You should see a small result that demonstrates Creating Pipelines. Exact formatting can differ by runtime, client, database state, operating system, or tool version.

Common mistakes

Watch for invalid input, unchecked errors, incorrect type assumptions, missing cleanup, unsafe permissions, injection risks, or code/query logic that handles only the happy path.

Practice exercise

Rebuild this example with your own data. Add one edge case, predict the result before running it, and explain why the final result is correct.

31.3 Filtering/Mapping

This topic teaches Filtering/Mapping as part of Streams. Learn the purpose first, then inspect the syntax and test it with small inputs before using it in production.

Code example

public class Main { public static void main(String[] args) { // Filtering/Mapping
System.out.println("Java example"); } }

Step-by-step explanation

Identify the values, objects, tables, or resources used by the example.
Read each statement in execution order.
Predict what the program or query should produce.
Run it in a safe local/test environment.
Change one input and explain the new result.

Expected output/result

You should see a small result that demonstrates Filtering/Mapping. Exact formatting can differ by runtime, client, database state, operating system, or tool version.

Common mistakes

Watch for invalid input, unchecked errors, incorrect type assumptions, missing cleanup, unsafe permissions, injection risks, or code/query logic that handles only the happy path.

Practice exercise

Rebuild this example with your own data. Add one edge case, predict the result before running it, and explain why the final result is correct.

31.4 Collecting/Aggregating

This topic teaches Collecting/Aggregating as part of Streams. Learn the purpose first, then inspect the syntax and test it with small inputs before using it in production.

Code example

public class Main { public static void main(String[] args) { // Collecting/Aggregating
System.out.println("Java example"); } }

Step-by-step explanation

Identify the values, objects, tables, or resources used by the example.
Read each statement in execution order.
Predict what the program or query should produce.
Run it in a safe local/test environment.
Change one input and explain the new result.

Expected output/result

You should see a small result that demonstrates Collecting/Aggregating. Exact formatting can differ by runtime, client, database state, operating system, or tool version.

Common mistakes

Watch for invalid input, unchecked errors, incorrect type assumptions, missing cleanup, unsafe permissions, injection risks, or code/query logic that handles only the happy path.

Practice exercise

Rebuild this example with your own data. Add one edge case, predict the result before running it, and explain why the final result is correct.

31.5 Performance and Side Effects

This topic teaches Performance and Side Effects as part of Streams. Learn the purpose first, then inspect the syntax and test it with small inputs before using it in production.

Code example

public class Main { public static void main(String[] args) { // Performance and Side Effects
System.out.println("Java example"); } }

Step-by-step explanation

Identify the values, objects, tables, or resources used by the example.
Read each statement in execution order.
Predict what the program or query should produce.
Run it in a safe local/test environment.
Change one input and explain the new result.

Expected output/result

You should see a small result that demonstrates Performance and Side Effects. Exact formatting can differ by runtime, client, database state, operating system, or tool version.

Common mistakes

Watch for invalid input, unchecked errors, incorrect type assumptions, missing cleanup, unsafe permissions, injection risks, or code/query logic that handles only the happy path.

Practice exercise

Rebuild this example with your own data. Add one edge case, predict the result before running it, and explain why the final result is correct.