@GwtCompatible(emulated=true) public final class Throwables extends Object
Throwable
.
See the Guava User Guide entry on Throwables.
Modifier and Type | Method and Description |
---|---|
static List<Throwable> |
getCausalChain(Throwable throwable)
Gets a
Throwable cause chain as a list. |
static <X extends Throwable> |
getCauseAs(Throwable throwable,
Class<X> expectedCauseType)
Returns
throwable 's cause, cast to expectedCauseType . |
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 List<StackTraceElement> |
lazyStackTrace(Throwable throwable)
Returns the stack trace of
throwable , possibly providing slower iteration over the full
trace but faster iteration over parts of the trace. |
static boolean |
lazyStackTraceIsLazy()
Returns whether
lazyStackTrace(java.lang.Throwable) will use the special implementation described in its
documentation. |
static RuntimeException |
propagate(Throwable throwable)
Deprecated.
Use
throw e or throw new RuntimeException(e) directly, or use a
combination of throwIfUnchecked(java.lang.Throwable) and throw new RuntimeException(e) . For
background on the deprecation, read Why we deprecated
Throwables.propagate . |
static <X extends Throwable> |
propagateIfInstanceOf(@Nullable Throwable throwable,
Class<X> declaredType)
Deprecated.
Use
throwIfInstanceOf(java.lang.Throwable, java.lang.Class<X>) , which has the same behavior but rejects null . |
static void |
propagateIfPossible(@Nullable Throwable throwable)
Deprecated.
Use
throwIfUnchecked(java.lang.Throwable) , which has the same behavior but rejects null . |
static <X extends Throwable> |
propagateIfPossible(@Nullable Throwable throwable,
Class<X> declaredType)
Propagates
throwable exactly as-is, if and only if it is an instance of RuntimeException , Error , or declaredType . |
static <X1 extends Throwable,X2 extends Throwable> |
propagateIfPossible(@Nullable 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 <X extends Throwable> |
throwIfInstanceOf(Throwable throwable,
Class<X> declaredType)
Throws
throwable if it is an instance of declaredType . |
static void |
throwIfUnchecked(Throwable throwable)
|
@GwtIncompatible public static <X extends Throwable> void throwIfInstanceOf(Throwable throwable, Class<X> declaredType) throws X extends Throwable
throwable
if it is an instance of declaredType
. Example usage:
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); }
X extends Throwable
@Deprecated @GwtIncompatible public static <X extends Throwable> void propagateIfInstanceOf(@Nullable Throwable throwable, Class<X> declaredType) throws X extends Throwable
throwIfInstanceOf(java.lang.Throwable, java.lang.Class<X>)
, which has the same behavior but rejects null
.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); }
X extends Throwable
public static void throwIfUnchecked(Throwable throwable)
throwable
if it is a RuntimeException
or Error
. Example usage:
for (Foo foo : foos) { try { foo.bar(); } catch (RuntimeException | Error t) { failure = t; } } if (failure != null) { throwIfUnchecked(failure); throw new AssertionError(failure); }
@Deprecated @GwtIncompatible public static void propagateIfPossible(@Nullable Throwable throwable)
throwIfUnchecked(java.lang.Throwable)
, which has the same behavior but rejects null
.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); }
@GwtIncompatible public static <X extends Throwable> void propagateIfPossible(@Nullable Throwable throwable, Class<X> declaredType) throws X extends Throwable
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); }
throwable
- the Throwable to possibly propagatedeclaredType
- the single checked exception type declared by the calling methodX extends Throwable
@GwtIncompatible public static <X1 extends Throwable,X2 extends Throwable> void propagateIfPossible(@Nullable Throwable throwable, Class<X1> declaredType1, Class<X2> declaredType2) throws X1 extends Throwable, X2 extends Throwable
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)
.throwable
- the Throwable to possibly propagatedeclaredType1
- any checked exception type declared by the calling methoddeclaredType2
- any other checked exception type declared by the calling methodX1 extends Throwable
@CanIgnoreReturnValue @GwtIncompatible @Deprecated public static RuntimeException propagate(Throwable throwable)
throw e
or throw new RuntimeException(e)
directly, or use a
combination of throwIfUnchecked(java.lang.Throwable)
and throw new RuntimeException(e)
. For
background on the deprecation, read Why we deprecated
Throwables.propagate
.throwable
as-is if it is an instance of RuntimeException
or Error
, or else as a last resort, wraps it in a RuntimeException
and then propagates.
This method always throws an exception. The RuntimeException
return type allows
client code to signal to the compiler that statements after the call are unreachable. Example
usage:
T doSomething() { try { return someMethodThatCouldThrowAnything(); } catch (IKnowWhatToDoWithThisException e) { return handle(e); } catch (Throwable t) { throw Throwables.propagate(t); } }
throwable
- the Throwable to propagatepublic static Throwable getRootCause(Throwable throwable)
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());
IllegalArgumentException
- if there is a loop in the causal chain@Beta public static List<Throwable> getCausalChain(Throwable throwable)
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));
throwable
- the non-null Throwable
to extract causes fromthrowable
IllegalArgumentException
- if there is a loop in the causal chain@Beta @GwtIncompatible public static <X extends Throwable> X getCauseAs(Throwable throwable, Class<X> expectedCauseType)
throwable
's cause, cast to expectedCauseType
.
Prefer this method instead of manually casting an exception's cause. For example, (IOException) e.getCause()
throws a ClassCastException
that discards the original
exception e
if the cause is not an IOException
, but Throwables.getCauseAs(e, IOException.class)
keeps e
as the ClassCastException
's cause.
ClassCastException
- if the cause cannot be cast to the expected type. The ClassCastException
's cause is throwable
.@GwtIncompatible public static String getStackTraceAsString(Throwable throwable)
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
Throwable.getStackTrace()
.@Beta @GwtIncompatible public static List<StackTraceElement> lazyStackTrace(Throwable throwable)
throwable
, possibly providing slower iteration over the full
trace but faster iteration over parts of the trace. Here, "slower" and "faster" are defined in
comparison to the normal way to access the stack trace, throwable.getStackTrace()
. Note, however, that this method's special implementation is not
available for all platforms and configurations. If that implementation is unavailable, this
method falls back to getStackTrace
. Callers that require the special implementation can
check its availability with lazyStackTraceIsLazy()
.
The expected (but not guaranteed) performance of the special implementation differs from
getStackTrace
in one main way: The lazyStackTrace
call itself returns quickly
by delaying the per-stack-frame work until each element is accessed. Roughly speaking:
getStackTrace
takes stackSize
time to return but then negligible time to
retrieve each element of the returned list.
lazyStackTrace
takes negligible time to return but then 1/stackSize
time
to retrieve each element of the returned list (probably slightly more than 1/stackSize
).
Note: The special implementation does not respect calls to throwable.setStackTrace
. Instead, it always reflects the original stack trace from the
exception's creation.
@Beta @GwtIncompatible public static boolean lazyStackTraceIsLazy()
lazyStackTrace(java.lang.Throwable)
will use the special implementation described in its
documentation.Copyright © 2010–2019. All rights reserved.