Package org.apache.groovy.util

Class JavaShell

java.lang.Object

org.apache.groovy.util.JavaShell

public class JavaShell
extends Object

A shell for compiling or running pure Java code in-memory using the platform's JavaCompiler. Compiled bytes are kept in a backing class loader (see getClassLoader()) and can optionally be written to disk via compileAllTo(String, Iterable, String, Path).

The className argument supplied to run, compile, compileAll and compileAllTo must be the fully-qualified binary name and match any package declaration in src: if the source begins with package com.example; and declares class Foo, pass "com.example.Foo", not "Foo". A mismatch produces a standard javac diagnostic ("class X is public, should be declared in a file named X.java"). Source with no package declaration takes a simple name (e.g. "Foo"); compileAllTo writes such a class directly under outputDir as Foo.class, while packaged classes land under the matching subdirectory (e.g. <outputDir>/com/example/Foo.class).

The Iterable<String> compiler-options parameter accepted by run, compile, compileAll and compileAllTo uses the same flags as the javac command line, with one token per element (so "-source" and "17" are two entries, not a single "-source 17" string). Examples:

• List.of("--release", "17") — target a specific Java release
• List.of("-source", "17", "-target", "17") — separate source/target levels
• List.of("-parameters") — retain formal parameter names
• List.of("-g") — emit debug information
• List.of("-Xlint:all", "-Werror") — enable all warnings and treat them as errors
• List.of("-proc:none") — disable annotation processing
• List.of("-classpath", extraJars) — extend the compile-time class path

The -d flag has no effect: in-memory output is always captured (and is additionally written to disk by compileAllTo). See the javac documentation for the complete list of supported flags.

Constructor Summary

Constructors

Constructor	Description
JavaShell()	Initializes a newly created JavaShell object
JavaShell(ClassLoader parentClassLoader)	Initializes a newly created JavaShell object

Method Summary

Modifier and Type	Method	Description
Class<?>	compile(String className, Iterable<String> options, String src)	Compile and return the main class
Class<?>	compile(String className, String src)	Compile and return the main class
Map<String,Class<?>>	compileAll(String className, Iterable<String> options, String src)	Compile and return all classes
Map<String,Class<?>>	compileAll(String className, String src)	Compile and return all classes
Map<String,Path>	compileAllTo(String className, Iterable<String> options, String src, Path outputDir)	Compile src and write each resulting class file beneath outputDir as a standard package directory tree (e.g.
Map<String,Path>	compileAllTo(String className, String src, Path outputDir)	Convenience overload of compileAllTo(String, Iterable, String, Path) that compiles with no extra compiler options.
org.apache.groovy.util.JavaShell.JavaShellClassLoader	getClassLoader()	When and only when compile(String, String) or compileAll(String, String) is invoked, returned class loader will reference the compiled classes.
void	run(String className, Iterable<String> options, String src, String... args)	Run main method
void	run(String className, String src, String... args)	Run main method

Methods inherited from class java.lang.Object

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

Constructor Details

JavaShell

public JavaShell()

Initializes a newly created JavaShell object

JavaShell

public JavaShell(ClassLoader parentClassLoader)

Initializes a newly created JavaShell object

Parameters:

parentClassLoader - the parent class loader for delegation

Method Details

run

public void run(String className,
 Iterable<String> options,
 String src,
 String... args)
         throws Throwable

Run main method

Parameters:

className - the main class name

options - compiler options

src - the source code

args - arguments for main method

Throws:

Throwable

run

public void run(String className,
 String src,
 String... args)
         throws Throwable

Run main method

Parameters:

className - the main class name

src - the source code

args - arguments for main method

Throws:

Throwable

compile

public Class<?> compile(String className,
 Iterable<String> options,
 String src)
                 throws IOException,
ClassNotFoundException

Compile and return the main class

Parameters:

className - the main class name

options - compiler options

src - the source code

Returns:

the main class

Throws:

IOException

ClassNotFoundException

compile

public Class<?> compile(String className,
 String src)
                 throws IOException,
ClassNotFoundException

Compile and return the main class

Parameters:

className - the main class name

src - the source code

Returns:

the main class

Throws:

IOException

ClassNotFoundException

compileAll

public Map<String,Class<?>> compileAll(String className,
 Iterable<String> options,
 String src)
                                throws IOException,
ClassNotFoundException

Compile and return all classes

Parameters:

className - the main class name

options - compiler options

src - the source code

Returns:

all classes

Throws:

IOException

ClassNotFoundException

compileAll

public Map<String,Class<?>> compileAll(String className,
 String src)
                                throws IOException,
ClassNotFoundException

Compile and return all classes

Parameters:

className - the main class name

src - the source code

Returns:

all classes

Throws:

IOException

ClassNotFoundException

compileAllTo

@Incubating
public Map<String,Path> compileAllTo(String className,
 Iterable<String> options,
 String src,
 Path outputDir)
                              throws IOException

Compile src and write each resulting class file beneath outputDir as a standard package directory tree (e.g. com.example.Foo$Bar becomes <outputDir>/com/example/Foo$Bar.class). Intermediate directories are created as needed; existing class files at those locations are overwritten. The compiled classes also remain available through getClassLoader().

Parameters:

className - the main class name (binary name, e.g. com.example.Foo)

options - compiler options; see the class-level documentation for the expected format

src - the source code

outputDir - root directory under which class files are written; created if absent

Returns:

a map from binary class name to the Path of the written .class file, iterating in the order the compiler emitted them (stable across invocations for the same source, but JDK-dependent — inner and auxiliary classes commonly appear before the enclosing class)

Throws:

IOException - if writing a class file fails

JavaShellCompilationException - if the source fails to compile

Since:

6.0.0

compileAllTo

@Incubating
public Map<String,Path> compileAllTo(String className,
 String src,
 Path outputDir)
                              throws IOException

Convenience overload of compileAllTo(String, Iterable, String, Path) that compiles with no extra compiler options.

Parameters:

className - the main class name (binary name)

src - the source code

outputDir - root directory under which class files are written; created if absent

Returns:

a map from binary class name to the Path of the written .class file

Throws:

IOException - if writing a class file fails

JavaShellCompilationException - if the source fails to compile

Since:

6.0.0

getClassLoader

public org.apache.groovy.util.JavaShell.JavaShellClassLoader getClassLoader()

When and only when compile(String, String) or compileAll(String, String) is invoked, returned class loader will reference the compiled classes.