Class MatchException

java.lang.Object

java.lang.Throwable

java.lang.Exception

java.lang.RuntimeException

java.lang.MatchException

All Implemented Interfaces:

Serializable

public final class MatchException
extends RuntimeException

Thrown to indicate an unexpected failure in pattern matching.

MatchException may be thrown when an exhaustive pattern matching language construct (such as a switch expression) encounters a value that does not match any of the specified patterns at run time, even though the construct has been deemed exhaustive. This is intentional and can arise from a number of cases:

• Separate compilation anomalies, where parts of the type hierarchy that the patterns reference have been changed, but the pattern matching construct has not been recompiled. For example, if a sealed interface has a different set of permitted subtypes at run time than it had at compile time, or if an enum class has a different set of enum constants at runtime than it had at compile time, or if the type hierarchy has been changed in some incompatible way between compile time and run time.
• null values and nested patterns involving sealed classes. If, for example, an interface I is sealed with two permitted subclasses A and B, and a record class R has a single component of type I, then the two record patterns R(A a) and R(B b) together are considered to be exhaustive for the type R, but neither of these patterns will match against the result of new R(null).
• null values and nested record patterns. Given a record class S with a single component of type T, where T is another record class with a single component of type String, then the nested record pattern R(S(var s)) is considered exhaustive for the type R but it does not match against the result of new R(null) (whereas it does match against the result of new R(new S(null)) does).

MatchException may also be thrown by the process of pattern matching a value against a pattern. For example, pattern matching involving a record pattern may require accessor methods to be implicitly invoked in order to extract the component values. If any of these accessor methods throws an exception, pattern matching completes abruptly and throws MatchException. The original exception will be set as a cause of the MatchException. No suppressed exceptions will be recorded.

See Java Language Specification:

14.11.3 Execution of a switch Statement
14.30.2 Pattern Matching
15.28.2 Run-Time Evaluation of switch Expressions

Since:

21

See Also:

• Serialized Form

Constructor Summary

Constructors

Constructor	Description
MatchException(String message, Throwable cause)	Constructs an MatchException with the specified detail message and cause.

Method Summary

Methods declared in class Throwable

addSuppressed, fillInStackTrace, getCause, getLocalizedMessage, getMessage, getStackTrace, getSuppressed, initCause, printStackTrace, printStackTrace, printStackTrace, setStackTrace, toString

Modifier and Type	Method	Description
final void	addSuppressed(Throwable exception)	The specified exception is going to be suppressed in order to give priority to this exception (primary exception) and to be appended to the list of suppressed exceptions.
Throwable	fillInStackTrace()	Record in the receiver a walkback from the point where this message was sent.
Throwable	getCause()	Answers the cause of this Throwable, or null if there is no cause.
String	getLocalizedMessage()	Answers the extra information message which was provided when the throwable was created.
String	getMessage()	Answers the extra information message which was provided when the throwable was created.
StackTraceElement[]	getStackTrace()	Answers an array of StackTraceElement.
final Throwable[]	getSuppressed()	Returns an array of exceptions suppressed, typically by the automatically generated code from the try-with-resources statement, in order to give priority to this exception (primary exception).
Throwable	initCause(Throwable throwable)	Initialize the cause of the receiver.
void	printStackTrace()	Outputs a printable representation of the receiver's walkback on the System.err stream.
void	printStackTrace(PrintStream err)	Outputs a printable representation of the receiver's walkback on the stream specified by the argument.
void	printStackTrace(PrintWriter err)	Outputs a printable representation of the receiver's walkback on the writer specified by the argument.
void	setStackTrace(StackTraceElement[] trace)	Sets the array of StackTraceElements.
String	toString()	Answers a string containing a concise, human-readable description of the receiver.

Methods declared in class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Modifier and Type	Method	Description
protected Object	clone()	Answers a new instance of the same class as the receiver, whose slots have been filled in with the values in the slots of the receiver.
boolean	equals(Object o)	Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.
protected void	finalize()	Deprecated, for removal: This API element is subject to removal in a future version. May cause performance issues, deadlocks and hangs.
final Class<? extends Object>	getClass()	Answers the unique instance of java.lang.Class which represents the class of the receiver.
int	hashCode()	Answers an integer hash code for the receiver.
final void	notify()	Causes one thread which is waiting on the receiver to be made ready to run.
final void	notifyAll()	Causes all threads which are waiting on the receiver to be made ready to run.
final void	wait()	Causes the thread which sent this message to be made not ready to run pending some change in the receiver (as indicated by notify or notifyAll).
final void	wait(long time)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.
final void	wait(long time, int frac)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.

Constructor Details

MatchException

public MatchException(String message,
 Throwable cause)

Constructs an MatchException with the specified detail message and cause.

Parameters:

message - the detail message (which is saved for later retrieval by the Throwable.getMessage() method).

cause - the cause (which is saved for later retrieval by the Throwable.getCause() method). (A null value is permitted, and indicates that the cause is nonexistent or unknown.)