EASYTUTORGUIDEJava • Java 26

Exceptions

Chapter 34 of 60 • beginner to advanced • code example for every topic

5 topics5 code examples10 Q&A

34.1 Throwing Errors 34.2 Catching Errors 34.3 Finally/Cleanup 34.4 Custom Errors 34.5 Error-Handling Best Practices

34.1 Throwing Errors

This topic teaches Throwing Errors as part of Exceptions. 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) { // Throwing Errors
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 Throwing Errors. 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.

34.2 Catching Errors

This topic teaches Catching Errors as part of Exceptions. 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) { // Catching Errors
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 Catching Errors. 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.

34.3 Finally/Cleanup

This topic teaches Finally/Cleanup as part of Exceptions. 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) { // Finally/Cleanup
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 Finally/Cleanup. 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.

34.4 Custom Errors

This topic teaches Custom Errors as part of Exceptions. 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) { // Custom Errors
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 Custom Errors. 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.

34.5 Error-Handling Best Practices

This topic teaches Error-Handling Best Practices as part of Exceptions. 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) { // Error-Handling Best Practices
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 Error-Handling Best Practices. 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.