- All Superinterfaces:
- AutoCloseable
- All Known Implementing Classes:
- DirectExecutionControl,- JdiDefaultExecutionControl,- JdiExecutionControl,- LocalExecutionControl,- RemoteExecutionControl,- StreamingExecutionControl
This interface specifies the functionality that must provided to implement a
 pluggable JShell execution engine.
 
The audience for this Service Provider Interface is engineers wishing to implement their own version of the execution engine in support of the JShell API.
A Snippet is compiled into code wrapped in a 'wrapper class'. The execution engine is used by the core JShell implementation to load and, for executable Snippets, execute the Snippet.
Methods defined in this interface should only be called by the core JShell implementation.
- Since:
- 9
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Nested Class SummaryNested ClassesModifier and TypeInterfaceDescriptionstatic final classBundles class name with class bytecodes.static classA class install (load or redefine) encountered a problem.static classUnbidden execution engine termination has occurred.static classThe abstract base of allExecutionControlexceptions.static classAn internal problem has occurred.static classThe command is not implemented.static classAn exception indicating that aDeclarationSnippetwith unresolved references has been encountered.static classThe abstract base of of exceptions specific to running user code.static classAn exception indicating that aninvoke(java.lang.String, java.lang.String)(or theoretically avarValue(java.lang.String, java.lang.String)) has been interrupted by astop().static classA 'normal' user exception occurred.
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Method SummaryModifier and TypeMethodDescriptionvoidaddToClasspath(String path) Adds the path to the execution class path.voidclose()Shuts down this execution engine.extensionCommand(String command, Object arg) Run a non-standard command (or a standard command from a newer version).static ExecutionControlgenerate(ExecutionEnv env, String spec) Search for a provider, then create and return theExecutionControlinstance.static ExecutionControlSearch for a provider, then create and return theExecutionControlinstance.Invokes an executable Snippet by calling a method on the specified wrapper class.voidload(ExecutionControl.ClassBytecodes[] cbcs) Attempts to load new classes.voidAttempts to redefine previously loaded classes.voidstop()Interrupts a running invoke.Returns the value of a variable.
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Method Details- 
loadvoid load(ExecutionControl.ClassBytecodes[] cbcs) throws ExecutionControl.ClassInstallException, ExecutionControl.NotImplementedException, ExecutionControl.EngineTerminationException Attempts to load new classes.- Parameters:
- cbcs- the class name and bytecodes to load
- Throws:
- ExecutionControl.ClassInstallException- exception occurred loading the classes, some or all were not loaded
- ExecutionControl.NotImplementedException- if not implemented
- ExecutionControl.EngineTerminationException- the execution engine has terminated
 
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redefinevoid redefine(ExecutionControl.ClassBytecodes[] cbcs) throws ExecutionControl.ClassInstallException, ExecutionControl.NotImplementedException, ExecutionControl.EngineTerminationException Attempts to redefine previously loaded classes.- Parameters:
- cbcs- the class name and bytecodes to redefine
- Throws:
- ExecutionControl.ClassInstallException- exception occurred redefining the classes, some or all were not redefined
- ExecutionControl.NotImplementedException- if not implemented
- ExecutionControl.EngineTerminationException- the execution engine has terminated
 
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invokeString invoke(String className, String methodName) throws ExecutionControl.RunException, ExecutionControl.EngineTerminationException, ExecutionControl.InternalException Invokes an executable Snippet by calling a method on the specified wrapper class. The method must have no arguments and return String.- Parameters:
- className- the class whose method should be invoked
- methodName- the name of method to invoke
- Returns:
- the result of the execution or null if no result
- Throws:
- ExecutionControl.UserException- the invoke raised a user exception
- ExecutionControl.ResolutionException- the invoke attempted to directly or indirectly invoke an unresolved snippet
- ExecutionControl.StoppedException- if the- invoke()was canceled by- stop()
- ExecutionControl.EngineTerminationException- the execution engine has terminated
- ExecutionControl.InternalException- an internal problem occurred
- ExecutionControl.RunException
 
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varValueString varValue(String className, String varName) throws ExecutionControl.RunException, ExecutionControl.EngineTerminationException, ExecutionControl.InternalException Returns the value of a variable.- Parameters:
- className- the name of the wrapper class of the variable
- varName- the name of the variable
- Returns:
- the value of the variable
- Throws:
- ExecutionControl.UserException- formatting the value raised a user exception
- ExecutionControl.ResolutionException- formatting the value attempted to directly or indirectly invoke an unresolved snippet
- ExecutionControl.StoppedException- if the formatting the value was canceled by- stop()
- ExecutionControl.EngineTerminationException- the execution engine has terminated
- ExecutionControl.InternalException- an internal problem occurred
- ExecutionControl.RunException
 
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addToClasspathvoid addToClasspath(String path) throws ExecutionControl.EngineTerminationException, ExecutionControl.InternalException Adds the path to the execution class path.- Parameters:
- path- the path to add
- Throws:
- ExecutionControl.EngineTerminationException- the execution engine has terminated
- ExecutionControl.InternalException- an internal problem occurred
 
- 
stopInterrupts a running invoke.- Throws:
- ExecutionControl.EngineTerminationException- the execution engine has terminated
- ExecutionControl.InternalException- an internal problem occurred
 
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extensionCommandObject extensionCommand(String command, Object arg) throws ExecutionControl.RunException, ExecutionControl.EngineTerminationException, ExecutionControl.InternalException Run a non-standard command (or a standard command from a newer version).- Parameters:
- command- the non-standard command
- arg- the commands argument
- Returns:
- the commands return value
- Throws:
- ExecutionControl.UserException- the command raised a user exception
- ExecutionControl.ResolutionException- the command attempted to directly or indirectly invoke an unresolved snippet
- ExecutionControl.StoppedException- if the command was canceled by- stop()
- ExecutionControl.EngineTerminationException- the execution engine has terminated
- ExecutionControl.NotImplementedException- if not implemented
- ExecutionControl.InternalException- an internal problem occurred
- ExecutionControl.RunException
 
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closevoid close()Shuts down this execution engine. Implementation should free all resources held by this execution engine.No calls to methods on this interface should be made after close. - Specified by:
- closein interface- AutoCloseable
 
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generatestatic ExecutionControl generate(ExecutionEnv env, String name, Map<String, String> parameters) throws ThrowableSearch for a provider, then create and return theExecutionControlinstance.- Parameters:
- env- the execution environment (provided by JShell)
- name- the name of provider
- parameters- the parameter map.
- Returns:
- the execution engine
- Throws:
- Throwable- an exception that occurred attempting to find or create the execution engine.
- IllegalArgumentException- if no ExecutionControlProvider has the specified- nameand- parameters.
 
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generateSearch for a provider, then create and return theExecutionControlinstance.- Parameters:
- env- the execution environment (provided by JShell)
- spec- the- ExecutionControlspec, which is described in the documentation of this package documentation.
- Returns:
- the execution engine
- Throws:
- Throwable- an exception that occurred attempting to find or create the execution engine.
- IllegalArgumentException- if no ExecutionControlProvider has the specified- nameand- parameters.
- IllegalArgumentException- if- specis malformed
 
 
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