Class JShell.Builder

Enclosing class:
JShell
public static class JShell.Builder
extends Object

Builder for JShell instances. Create custom instances of JShell by using the setter methods on this class. After zero or more of these, use the build() method to create a JShell instance. These can all be chained. For example, setting the remote output and error streams: 

JShell myShell =
       JShell.builder()
         .out(myOutStream)
         .err(myErrStream)
         .build();
If no special set-up is needed, just use JShell.builder().build() or the short-cut equivalent JShell.create().

Methods

Modifier and Type Method Description
JShell build()

Builds a JShell state engine.
JShell.Builder compilerOptions​(String... options)

Adds compiler options.
JShell.Builder err​(PrintStream err)

Sets the error output for the running evaluation (it's System.err).
JShell.Builder executionEngine​(String executionControlSpec)

Sets the custom engine for execution.
JShell.Builder executionEngine​(ExecutionControlProvider executionControlProvider, Map<String,​String> executionControlParameters)

Sets the custom engine for execution.
JShell.Builder fileManager​(Function<StandardJavaFileManager,​StandardJavaFileManager> mapping)

Configure the FileManager to be used by compilation and source analysis.
JShell.Builder idGenerator​(BiFunction<Snippet,​Integer,​String> generator)

Sets the generator of identifying names for Snippets.
JShell.Builder in​(InputStream in)

Sets the input for the running evaluation (it's System.in).
JShell.Builder out​(PrintStream out)

Sets the output for the running evaluation (it's System.out).
JShell.Builder remoteVMOptions​(String... options)

Sets additional VM options for launching the VM.
JShell.Builder tempVariableNameGenerator​(Supplier<String> generator)

Sets a generator of temp variable names for VarSnippet of Snippet.SubKind.TEMP_VAR_EXPRESSION_SUBKIND.

Methods declared in class java.lang.Object

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

Methods

in

public JShell.Builder in(InputStream in)

Sets the input for the running evaluation (it's System.in). Note: applications that use System.in for snippet or other user input cannot use System.in as the input stream for the remote process.

The read method of the InputStream may throw the InterruptedIOException to signal the user canceled the input. The currently running snippet will be automatically stopped.

The default, if this is not set, is to provide an empty input stream -- new ByteArrayInputStream(new byte[0]).

Parameters:
in - the InputStream to be channelled to System.in in the remote execution process
Returns:
the Builder instance (for use in chained initialization)

out

public JShell.Builder out(PrintStream out)

Sets the output for the running evaluation (it's System.out). The controlling process and the remote process can share System.out.

The default, if this is not set, is System.out.

Parameters:
out - the PrintStream to be channelled to System.out in the remote execution process
Returns:
the Builder instance (for use in chained initialization)

err

public JShell.Builder err(PrintStream err)

Sets the error output for the running evaluation (it's System.err). The controlling process and the remote process can share System.err.

The default, if this is not set, is System.err.

Parameters:
err - the PrintStream to be channelled to System.err in the remote execution process
Returns:
the Builder instance (for use in chained initialization)

tempVariableNameGenerator

public JShell.Builder tempVariableNameGenerator(Supplier<String> generator)

Sets a generator of temp variable names for VarSnippet of Snippet.SubKind.TEMP_VAR_EXPRESSION_SUBKIND.

Do not use this method unless you have explicit need for it.

The generator will be used for newly created VarSnippet instances. The name of a variable is queried with PersistentSnippet.name().

The callback is sent during the processing of the snippet, the JShell state is not stable. No calls whatsoever on the JShell instance may be made from the callback.

The generated name must be unique within active snippets.

The default behavior (if this is not set or generator is null) is to generate the name as a sequential number with a prefixing dollar sign ("$").

Parameters:
generator - the Supplier to generate the temporary variable name string or null
Returns:
the Builder instance (for use in chained initialization)

idGenerator

public JShell.Builder idGenerator(BiFunction<Snippet,​Integer,​String> generator)

Sets the generator of identifying names for Snippets.

Do not use this method unless you have explicit need for it.

The generator will be used for newly created Snippet instances. The identifying name (id) is accessed with Snippet.id() and can be seen in the StackTraceElement.getFileName() for a EvalException and UnresolvedReferenceException.

The inputs to the generator are the Snippet and an integer. The integer will be the same for two Snippets which would overwrite one-another, but otherwise is unique.

The callback is sent during the processing of the snippet and the Snippet and the state as a whole are not stable. No calls to change system state (including Snippet state) should be made. Queries of Snippet may be made except to Snippet.id(). No calls on the JShell instance may be made from the callback, except to status(Snippet).

The default behavior (if this is not set or generator is null) is to generate the id as the integer converted to a string.

Parameters:
generator - the BiFunction to generate the id string or null
Returns:
the Builder instance (for use in chained initialization)

remoteVMOptions

public JShell.Builder remoteVMOptions(String... options)

Sets additional VM options for launching the VM.

Parameters:
options - The options for the remote VM
Returns:
the Builder instance (for use in chained initialization)

compilerOptions

public JShell.Builder compilerOptions(String... options)

Adds compiler options. These additional options will be used on parsing, analysis, and code generation calls to the compiler. Options which interfere with results are not supported and have undefined effects on JShell's operation.

Parameters:
options - the addition options for compiler invocations
Returns:
the Builder instance (for use in chained initialization)

executionEngine

public JShell.Builder executionEngine(String executionControlSpec)

Sets the custom engine for execution. Snippet execution will be provided by the ExecutionControl instance selected by the specified execution control spec. Use, at most, one of these overloaded executionEngine builder methods.

Parameters:
executionControlSpec - the execution control spec, which is documented in the jdk.jshell.spi package documentation.
Returns:
the Builder instance (for use in chained initialization)

executionEngine

public JShell.Builder executionEngine(ExecutionControlProvider executionControlProvider,
                                      Map<String,​String> executionControlParameters)

Sets the custom engine for execution. Snippet execution will be provided by the specified ExecutionControl instance. Use, at most, one of these overloaded executionEngine builder methods.

Parameters:
executionControlProvider - the provider to supply the execution engine
executionControlParameters - the parameters to the provider, or null for default parameters
Returns:
the Builder instance (for use in chained initialization)

fileManager

public JShell.Builder fileManager(Function<StandardJavaFileManager,​StandardJavaFileManager> mapping)

Configure the FileManager to be used by compilation and source analysis. If not set or passed null, the compiler's standard file manager will be used (identity mapping). For use in special applications where the compiler's normal file handling needs to be overridden. See the file manager APIs for more information. The file manager input enables forwarding file managers, if this is not needed, the incoming file manager can be ignored (constant function).

Parameters:
mapping - a function that given the compiler's standard file manager, returns a file manager to use
Returns:
the Builder instance (for use in chained initialization)

build

public JShell build()
             throws IllegalStateException

Builds a JShell state engine. This is the entry-point to all JShell functionality. This creates a remote process for execution. It is thus important to close the returned instance.

Returns:
the state engine
Throws:
IllegalStateException - if the JShell instance could not be created.

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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/11/docs/api/jdk.jshell/jdk/jshell/JShell.Builder.html