Throwable, Exception Class

https://codedragon.tistory.com/4447#:~:text=%C2%B7%20Throwable%20%ED%81%B4%EB%9E%98%EC%8A%A4%EB%8A%94%20%EB%AA%A8%EB%93%A0%20%EC%98%88%EC%99%B8,%ED%81%B4%EB%9E%98%EC%8A%A4%EC%9D%98%20%EB%B6%80%EB%AA%A8%20%ED%81%B4%EB%9E%98%EC%8A%A4%EC%9E%85%EB%8B%88%EB%8B%A4.&text=RuntimeException%20%ED%81%B4%EB%9E%98%EC%8A%A4%EB%A5%BC%20%EC%83%81%EC%86%8D%EB%B0%9B%EB%8A%94,%EC%98%88%EC%99%B8%EB%93%A4%EB%A1%9C%20%EA%B5%AC%EC%84%B1%EB%90%A9%EB%8B%88%EB%8B%A4.

java.lang.Throwable 클래스, JAVA의 예외 종류 및 구조도, 자바프로그램의 예외 처리 과정

 

간략화 해서 표현한 클래스 구조

Throwable 클래스는

 

자바에서 예외를 처리하기 위한 최상위 클래스

Throwable 클래스를 상속받은 자식들을 예외처리에서 사용하게 된다.

 * The {@code Throwable} class is the superclass of all errors and
 * exceptions in the Java language. Only objects that are instances of this
 * class (or one of its subclasses) are thrown by the Java Virtual Machine or
 * can be thrown by the Java {@code throw} statement. Similarly, only
 * this class or one of its subclasses can be the argument type in a
 * {@code catch} clause.

 

Exception 클래스

try-catch를 통해 잡을 수 있는 상황에서 사용되는 클래스.

 * The class {@code Exception} and its subclasses are a form of
 * {@code Throwable} that indicates conditions that a reasonable
 * application might want to catch.
 *
 * <p>The class {@code Exception} and any subclasses that are not also
 * subclasses of {@link RuntimeException} are <em>checked
 * exceptions</em>.  Checked exceptions need to be declared in a
 * method or constructor's {@code throws} clause if they can be thrown
 * by the execution of the method or constructor and propagate outside
 * the method or constructor boundary.
 *

 

 

Error 클래스

Thorwable의 서브 클래스이고, try나 catch로 잡으면 안되는 심각한 문제에 대비하여 사용함.

 

 * An {@code Error} is a subclass of {@code Throwable}
 * that indicates serious problems that a reasonable application
 * should not try to catch. Most such errors are abnormal conditions.
 * The {@code ThreadDeath} error, though a "normal" condition,
 * is also a subclass of {@code Error} because most applications
 * should not try to catch it.
 * <p>
 * A method is not required to declare in its {@code throws}
 * clause any subclasses of {@code Error} that might be thrown
 * during the execution of the method but not caught, since these
 * errors are abnormal conditions that should never occur.
 *
 * That is, {@code Error} and its subclasses are regarded as unchecked
 * exceptions for the purposes of compile-time checking of exceptions.
 *

 

 

RuntimeException

 * {@code RuntimeException} is the superclass of those
 * exceptions that can be thrown during the normal operation of the
 * Java Virtual Machine.
 *
 * <p>{@code RuntimeException} and its subclasses are <em>unchecked
 * exceptions</em>.  Unchecked exceptions do <em>not</em> need to be
 * declared in a method or constructor's {@code throws} clause if they
 * can be thrown by the execution of the method or constructor and
 * propagate outside the method or constructor boundary.
 *

 

Exception의 서브 클래스. UncheckedException은 이 클래스를 통해서 잡아야 한다.

 

 

더 알아보기

+ 자바7에서는 or을 의미하는 파이프로 연결하여 간단하게 처리할 수 있다.

try{

}catch(IllegalArgumentException | FileNotFoundException){

}

 

그리고 AutoCloseable이라는 인터페이스가 추가되어, try-with-resource를 사용할 때에는 이 인터페이스를 구현한 클래스는 별도로 close()를 호출해줄 필요가 없다. 즉 finally 문장에서 close()를 처리하기 위해서 코드의 가독성을 떨어뜨릴 필요가 없다.

 

즉 AutoCloseable을 구현한 객체는 Fainlly 문장안에서 별도로 처리할 필요가 없다.