Throwable Class
Definition
Important
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The Throwable class is the superclass of all errors and
exceptions in the Java language.
[Android.Runtime.Register("java/lang/Throwable", DoNotGenerateAcw=true)]
public class Throwable : Exception, IDisposable, Java.Interop.IJavaPeerable, Java.IO.ISerializable[<Android.Runtime.Register("java/lang/Throwable", DoNotGenerateAcw=true)>]
type Throwable = class
inherit Exception
interface IJavaObject
interface IDisposable
interface IJavaPeerable
interface ISerializable- Inheritance
-
Throwable
- Derived
- Attributes
- Implements
Remarks
The 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 throw statement. Similarly, only this class or one of its subclasses can be the argument type in a catch clause.
For the purposes of compile-time checking of exceptions, Throwable and any subclass of Throwable that is not also a subclass of either RuntimeException or Error are regarded as checked exceptions.
Instances of two subclasses, java.lang.Error and java.lang.Exception, are conventionally used to indicate that exceptional situations have occurred. Typically, these instances are freshly created in the context of the exceptional situation so as to include relevant information (such as stack trace data).
A throwable contains a snapshot of the execution stack of its thread at the time it was created. It can also contain a message string that gives more information about the error. Over time, a throwable can Throwable#addSuppressed suppress other throwables from being propagated. Finally, the throwable can also contain a cause: another throwable that caused this throwable to be constructed. The recording of this causal information is referred to as the chained exception facility, as the cause can, itself, have a cause, and so on, leading to a "chain" of exceptions, each caused by another.
One reason that a throwable may have a cause is that the class that throws it is built atop a lower layered abstraction, and an operation on the upper layer fails due to a failure in the lower layer. It would be bad design to let the throwable thrown by the lower layer propagate outward, as it is generally unrelated to the abstraction provided by the upper layer. Further, doing so would tie the API of the upper layer to the details of its implementation, assuming the lower layer's exception was a checked exception. Throwing a "wrapped exception" (i.e., an exception containing a cause) allows the upper layer to communicate the details of the failure to its caller without incurring either of these shortcomings. It preserves the flexibility to change the implementation of the upper layer without changing its API (in particular, the set of exceptions thrown by its methods).
A second reason that a throwable may have a cause is that the method that throws it must conform to a general-purpose interface that does not permit the method to throw the cause directly. For example, suppose a persistent collection conforms to the java.util.Collection Collection interface, and that its persistence is implemented atop java.io. Suppose the internals of the add method can throw an java.io.IOException IOException. The implementation can communicate the details of the IOException to its caller while conforming to the Collection interface by wrapping the IOException in an appropriate unchecked exception. (The specification for the persistent collection should indicate that it is capable of throwing such exceptions.)
A cause can be associated with a throwable in two ways: via a constructor that takes the cause as an argument, or via the #initCause(Throwable) method. New throwable classes that wish to allow causes to be associated with them should provide constructors that take a cause and delegate (perhaps indirectly) to one of the Throwable constructors that takes a cause.
Because the initCause method is public, it allows a cause to be associated with any throwable, even a "legacy throwable" whose implementation predates the addition of the exception chaining mechanism to Throwable.
By convention, class Throwable and its subclasses have two constructors, one that takes no arguments and one that takes a String argument that can be used to produce a detail message. Further, those subclasses that might likely have a cause associated with them should have two more constructors, one that takes a Throwable (the cause), and one that takes a String (the detail message) and a Throwable (the cause).
Added in 1.0.
Java documentation for java.lang.Throwable.
Portions of this page are modifications based on work created and shared by the Android Open Source Project and used according to terms described in the Creative Commons 2.5 Attribution License.
Constructors
| Throwable() |
Constructs a new throwable with |
| Throwable(IntPtr, JniHandleOwnership) |
A constructor used when creating managed representations of JNI objects; called by the runtime. |
| Throwable(String, Throwable, Boolean, Boolean) |
Constructs a new throwable with the specified detail message, cause, #addSuppressed suppression enabled or disabled, and writable stack trace enabled or disabled. |
| Throwable(String, Throwable) |
Constructs a new throwable with the specified detail message and cause. |
| Throwable(String) |
Constructs a new throwable with the specified detail message. |
| Throwable(Throwable) |
Constructs a new throwable with the specified cause and a detail
message of |
Fields
| is_generated |
Properties
| Cause |
Returns the cause of this throwable or |
| Class | |
| Handle |
The handle to the underlying Android instance. |
| JniIdentityHashCode | |
| JniPeerMembers | |
| LocalizedMessage |
Creates a localized description of this throwable. |
| Message |
Returns the detail message string of this throwable. |
| PeerReference | |
| StackTrace | |
| ThresholdClass |
This API supports the Mono for Android infrastructure and is not intended to be used directly from your code. |
| ThresholdType |
This API supports the Mono for Android infrastructure and is not intended to be used directly from your code. |
Methods
| AddSuppressed(Throwable) |
Appends the specified exception to the exceptions that were suppressed in order to deliver this exception. |
| Dispose() | |
| Dispose(Boolean) | |
| FillInStackTrace() |
Fills in the execution stack trace. |
| Finalize() | |
| FromException(Exception) | |
| GetStackTrace() |
Provides programmatic access to the stack trace information printed by
|
| GetSuppressed() |
Returns an array containing all of the exceptions that were
suppressed, typically by the |
| InitCause(Throwable) |
Initializes the cause of this throwable to the specified value. |
| PrintStackTrace() |
Prints this throwable and its backtrace to the standard error stream. |
| PrintStackTrace(PrintStream) |
Prints this throwable and its backtrace to the specified print stream. |
| PrintStackTrace(PrintWriter) |
Prints this throwable and its backtrace to the specified print writer. |
| SetHandle(IntPtr, JniHandleOwnership) |
Sets the Handle property. |
| SetStackTrace(StackTraceElement[]) |
Sets the stack trace elements that will be returned by
|
| ToException(Throwable) | |
| ToString() | |
| UnregisterFromRuntime() | |
Explicit Interface Implementations
Extension Methods
| JavaCast<TResult>(IJavaObject) |
Performs an Android runtime-checked type conversion. |
| JavaCast<TResult>(IJavaObject) | |
| GetJniTypeName(IJavaPeerable) | |