Exceptions without confusion

Catch only what you can recover from; let everything else carry context.

Beginner 13 min read Lesson 8 of 300 Challenge included

What you will be able to do

Do not use exceptions for ordinary control flow.
Wrap low-level exceptions in a domain exception with context.
Use try-with-resources for files and connections.

In plain English

Checked exceptions are part of a method signature; unchecked exceptions usually indicate programming errors. A catch block should either recover, translate or add context. Never swallow an exception with an empty catch.

ReadFile.javaJava

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;

public String readNotes(Path path) {
    try {
        return Files.readString(path);
    } catch (IOException error) {
        throw new IllegalStateException("Could not read " + path, error);
    }
}

Your turn

Translate an IOException

Medium

Catch an IOException while reading a path and throw an IllegalStateException with context.

JAVA · starter

try {
    return Files.readString(path);
} catch (IOException error) {
}

Check your understanding before moving on.

Knowledge checkQuestion 1

What does try-with-resources guarantee?

Select an answer to continue

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