Organized notes in the head (Java-Exceptions)

My Java environment

• Java11

try-catch-finally

• Describe in the order of try-catch-finally. It's OK without the catch clause.
• Only one try clause and one finally clause can be described. You can write multiple catch clauses.
• Example of writing a return statement in both the catch clause and the finally clause ↓

public class Test {
    public static void main(String... args) {
        System.out.println(getException());
    }

    private static String getException() {
        try {
            throw new Exception();
        } catch (Exception e) {
            return "catch!";
        } finally {
            return "finally!";
        }
    }
}

The execution result is

finally!

Exception class

• Inheritance relationship

Throwable
        -> Error
        -> Exception
            -> RuntimeException

Error

• Events that cannot be dealt with by the program
• Subclasses include StackOverFlow
• Inherit ʻError` to be classified as an error
• try-catch and throws are not enforced, can be written

ʻExceptionandRuntimeException`

• Events that the program can handle

Exception

• Inspection exception
• The compiler checks if exception handling is written
• Excluding RuntimeException and its subclasses
• Force either try-catch or throws

RuntimeException

• Unchecked exception
• The compiler does not check if exception handling is written
• try-catch and throws are not enforced, can be written