public class JavaShell
extends ObjectA 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 releaseList.of("-source", "17", "-target", "17") — separate source/target levelsList.of("-parameters") — retain formal parameter namesList.of("-g") — emit debug informationList.of("-Xlint:all", "-Werror") — enable all warnings and treat them as errorsList.of("-proc:none") — disable annotation processingList.of("-classpath", extraJars) — extend the compile-time class path-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 and description |
|---|
JavaShell()Initializes a newly created JavaShell object |
JavaShell(ClassLoader parentClassLoader)Initializes a newly created JavaShell object |
| Type Params | Return Type | Name and description |
|---|---|---|
|
public Class<?> |
compile(String className, Iterable<String> options, String src)Compile and return the main class |
|
public Class<?> |
compile(String className, String src)Compile and return the main class |
|
public Map<String, Class<?>> |
compileAll(String className, Iterable<String> options, String src)Compile and return all classes |
|
public Map<String, Class<?>> |
compileAll(String className, String src)Compile and return all classes |
|
public 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. |
|
public 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. |
|
public JavaShell.JavaShellClassLoader |
getClassLoader()When and only when compile(String, String) or compileAll(String, String) is invoked, returned class loader will reference the compiled classes. |
|
public void |
run(String className, Iterable<String> options, String src, String args)Run main method |
|
public void |
run(String className, String src, String args)Run main method |
Initializes a newly created JavaShell object
Initializes a newly created JavaShell object
parentClassLoader - the parent class loader for delegationCompile and return the main class
className - the main class nameoptions - compiler optionssrc - the source codeCompile and return the main class
className - the main class namesrc - the source codeCompile and return all classes
className - the main class nameoptions - compiler optionssrc - the source codeCompile and return all classes
className - the main class namesrc - the source code 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().
className - the main class name (binary name, e.g. com.example.Foo)options - compiler options; see the
class-level documentation for the expected formatsrc - the source codeoutputDir - root directory under which class files are written; created if absent.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)Convenience overload of compileAllTo(String, Iterable, String, Path) that compiles with no extra compiler options.
className - the main class name (binary name)src - the source codeoutputDir - root directory under which class files are written; created if absent.class fileWhen and only when compile(String, String) or compileAll(String, String) is invoked, returned class loader will reference the compiled classes.
Run main method
className - the main class nameoptions - compiler optionssrc - the source codeargs - arguments for main methodCopyright © 2003-2026 The Apache Software Foundation. All rights reserved.