EASYTUTORGUIDEJava • Java 26

JVM Memory, Garbage Collection, and Performance

Chapter 58 of 60 • beginner to advanced • code example for every topic

5 topics5 code examples10 Q&A

58.1 Creating Collections 58.2 Adding and Removing 58.3 Searching and Iterating 58.4 Sorting/Transforming 58.5 Choosing the Right Collection

58.1 Creating Collections

This topic teaches Creating Collections as part of JVM Memory, Garbage Collection, and Performance. 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){ List<Integer> xs=new ArrayList<>(List.of(3,1,2)); Collections.sort(xs); System.out.println(xs); } }

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 Collections. 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.

58.2 Adding and Removing

This topic teaches Adding and Removing as part of JVM Memory, Garbage Collection, and Performance. 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) { // Adding and Removing
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 Adding and Removing. 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.

58.3 Searching and Iterating

This topic teaches Searching and Iterating as part of JVM Memory, Garbage Collection, and Performance. 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) { // Searching and Iterating
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 Searching and Iterating. 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.

58.4 Sorting/Transforming

This topic teaches Sorting/Transforming as part of JVM Memory, Garbage Collection, and Performance. 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) { // Sorting/Transforming
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 Sorting/Transforming. 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.

58.5 Choosing the Right Collection

This topic teaches Choosing the Right Collection as part of JVM Memory, Garbage Collection, and Performance. 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){ List<Integer> xs=new ArrayList<>(List.of(3,1,2)); Collections.sort(xs); System.out.println(xs); } }

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 Choosing the Right Collection. 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.