Guava : Throwables

1. 메소드 목록

2. 메소드 설명

1. throwIfInstanceOf : declaredType의 인스턴스인 경우에만 throwable을 던진다

 for (Foo foo : foos) {
   try {
     foo.bar();
   } catch (BarException | RuntimeException | Error t) {
     failure = t;
   }
 }
 if (failure != null) {
   throwIfInstanceOf(failure, BarException.class);
   throwIfUnchecked(failure);
   throw new AssertionError(failure);
 }

2. throwIfUnchecked : RuntimeException이나 Error의 경우에만 throwable을 던진다.

 for (Foo foo : foos) {
   try {
     foo.bar();
   } catch (RuntimeException | Error t) {
     failure = t;
   }
 }
 if (failure != null) {
   throwIfUnchecked(failure);
   throw new AssertionError(failure);
 }

3. propagateIfPossible : 정확히 RuntimeException, Error나 declaredType의 인스턴스인 경우에만 예외를 전파한다.

try {
   someMethodThatCouldThrowAnything();
 } catch (IKnowWhatToDoWithThisException e) {
   handle(e);
 } catch (Throwable t) {
   Throwables.propagateIfPossible(t, OtherException.class);
   throw new RuntimeException("unexpected", t);
 }

3. 동작 원리

public void doSomething() 
    throws IOException, SQLException {

    try {
        someMethodThatCouldThrowAnything();
    } catch (IKnowWhatToDoWithThisException e) {
        handle(e);
    } catch (Throwable t) {
        Throwables.propagateIfInstanceOf(t, IOException.class);
        Throwables.propagateIfInstanceOf(t, SQLException.class);
        throw Throwables.propagate(t);
    }  
}

public void doSomething() 
    throws IOException, SQLException {

    try {
        someMethodThatCouldThrowAnything();
    } catch (IKnowWhatToDoWithThisException e) {
        handle(e);
    } catch (SQLException ex) {
        throw ex;
    } catch (IOException ex) {
        throw ex;
    } catch (Throwable t) {
        throw new RuntimeException(t);
    }  
}

참고

• https://guava.dev/releases/snapshot/api/docs/com/google/common/base/Throwables.html#propagateIfPossible-java.lang.Throwable-java.lang.Class-
• https://stackoverflow.com/questions/5090417/how-do-i-use-throwables-propagateifinstanceof-from-google-guava