public final class

Throwables

extends Object
java.lang.Object
   ↳ com.facebook.common.internal.Throwables

Class Overview

Static utility methods pertaining to instances of Throwable.

See the Guava User Guide entry on Throwables.

Summary

Public Methods
static List<Throwable> getCausalChain(Throwable throwable)
Gets a Throwable cause chain as a list.
static Throwable getRootCause(Throwable throwable)
Returns the innermost cause of throwable.
static String getStackTraceAsString(Throwable throwable)
Returns a string containing the result of toString(), followed by the full, recursive stack trace of throwable.
static RuntimeException propagate(Throwable throwable)
Propagates throwable as-is if it is an instance of RuntimeException or Error, or else as a last resort, wraps it in a RuntimeException then propagates.
static <X extends Throwable> void propagateIfInstanceOf(Throwable throwable, Class<X> declaredType)
Propagates throwable exactly as-is, if and only if it is an instance of declaredType.
static <X1 extends Throwable, X2 extends Throwable> void propagateIfPossible(Throwable throwable, Class<X1> declaredType1, Class<X2> declaredType2)
Propagates throwable exactly as-is, if and only if it is an instance of RuntimeException, Error, declaredType1, or declaredType2.
static void propagateIfPossible(Throwable throwable)
Propagates throwable exactly as-is, if and only if it is an instance of RuntimeException or Error.
static <X extends Throwable> void propagateIfPossible(Throwable throwable, Class<X> declaredType)
Propagates throwable exactly as-is, if and only if it is an instance of RuntimeException, Error, or declaredType.
[Expand]
Inherited Methods
From class java.lang.Object

Public Methods

public static List<Throwable> getCausalChain (Throwable throwable)

Gets a Throwable cause chain as a list. The first entry in the list will be throwable followed by its cause hierarchy. Note that this is a snapshot of the cause chain and will not reflect any subsequent changes to the cause chain.

Here's an example of how it can be used to find specific types of exceptions in the cause chain:

 Iterables.filter(Throwables.getCausalChain(e), IOException.class));
 

Parameters
throwable the non-null Throwable to extract causes from
Returns
  • an unmodifiable list containing the cause chain starting with throwable

public static Throwable getRootCause (Throwable throwable)

Returns the innermost cause of throwable. The first throwable in a chain provides context from when the error or exception was initially detected. Example usage:

   assertEquals("Unable to assign a customer id",
       Throwables.getRootCause(e).getMessage());
 

public static String getStackTraceAsString (Throwable throwable)

Returns a string containing the result of toString(), followed by the full, recursive stack trace of throwable. Note that you probably should not be parsing the resulting string; if you need programmatic access to the stack frames, you can call getStackTrace().

public static RuntimeException propagate (Throwable throwable)

Propagates throwable as-is if it is an instance of RuntimeException or Error, or else as a last resort, wraps it in a RuntimeException then propagates.

This method always throws an exception. The RuntimeException return type is only for client code to make Java type system happy in case a return value is required by the enclosing method. Example usage:

   T doSomething() {
     try {
       return someMethodThatCouldThrowAnything();
     } catch (IKnowWhatToDoWithThisException e) {
       return handle(e);
     } catch (Throwable t) {
       throw Throwables.propagate(t);
     }
   }
 

Parameters
throwable the Throwable to propagate
Returns
  • nothing will ever be returned; this return type is only for your convenience, as illustrated in the example above

public static void propagateIfInstanceOf (Throwable throwable, Class<X> declaredType)

Propagates throwable exactly as-is, if and only if it is an instance of declaredType. Example usage:

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

Throws
Throwable

public static void propagateIfPossible (Throwable throwable, Class<X1> declaredType1, Class<X2> declaredType2)

Propagates throwable exactly as-is, if and only if it is an instance of RuntimeException, Error, declaredType1, or declaredType2. In the unlikely case that you have three or more declared checked exception types, you can handle them all by invoking these methods repeatedly. See usage example in propagateIfPossible(Throwable, Class).

Parameters
throwable the Throwable to possibly propagate
declaredType1 any checked exception type declared by the calling method
declaredType2 any other checked exception type declared by the calling method
Throws
Throwable
Throwable

public static void propagateIfPossible (Throwable throwable)

Propagates throwable exactly as-is, if and only if it is an instance of RuntimeException or Error. Example usage:

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

public static void propagateIfPossible (Throwable throwable, Class<X> declaredType)

Propagates throwable exactly as-is, if and only if it is an instance of RuntimeException, Error, or declaredType. Example usage:

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

Parameters
throwable the Throwable to possibly propagate
declaredType the single checked exception type declared by the calling method
Throws
Throwable