MatchException

public final class MatchException
extends RuntimeException

java.lang.Object
   ↳ java.lang.Throwable
     ↳ java.lang.Exception
       ↳ java.lang.RuntimeException
         ↳ java.lang.MatchException


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.

Summary

Public constructors

MatchException(String message, Throwable cause)

Constructs an MatchException with the specified detail message and cause.

Inherited methods

final void addSuppressed(Throwable exception)

Appends the specified exception to the exceptions that were suppressed in order to deliver this exception.

Throwable fillInStackTrace()

Fills in the execution stack trace.

Throwable getCause()

Returns the cause of this throwable or null if the cause is nonexistent or unknown.

String getLocalizedMessage()

Creates a localized description of this throwable.

String getMessage()

Returns the detail message string of this throwable.

StackTraceElement[] getStackTrace()

Provides programmatic access to the stack trace information printed by printStackTrace().

final Throwable[] getSuppressed()

Returns an array containing all of the exceptions that were suppressed, typically by the try-with-resources statement, in order to deliver this exception.

Throwable initCause(Throwable cause)

Initializes the cause of this throwable to the specified value.

void printStackTrace()

Prints this throwable and its backtrace to the standard error stream.

void printStackTrace(PrintWriter s)

Prints this throwable and its backtrace to the specified print writer.

void printStackTrace(PrintStream s)

Prints this throwable and its backtrace to the specified print stream.

void setStackTrace(StackTraceElement[] stackTrace)

Sets the stack trace elements that will be returned by getStackTrace() and printed by printStackTrace() and related methods.

String toString()

Returns a short description of this throwable.

Object clone()

Creates and returns a copy of this object.

boolean equals(Object obj)

Indicates whether some other object is "equal to" this one.

void finalize()

Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.

final Class<?> getClass()

Returns the runtime class of this Object.

int hashCode()

Returns a hash code value for the object.

final void notify()

Wakes up a single thread that is waiting on this object's monitor.

final void notifyAll()

Wakes up all threads that are waiting on this object's monitor.

String toString()

Returns a string representation of the object.

final void wait(long timeoutMillis, int nanos)

Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

final void wait(long timeoutMillis)

Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

final void wait()

Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

Public constructors

MatchException

public MatchException (String message, 
                Throwable cause)

Constructs an MatchException with the specified detail message and cause.

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

cause Throwable: 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.)