I am making a tool that will write .java files, then (hopefully) compile those files to .class files. All in one process, the user selects a file directory where multiple .java files are written. Now I want the program to compile these Java files.
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2 Answers
JavaCompiler is your friend. Check the documentation here
And here an example on how you could use the compiler API
JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
DiagnosticCollector<JavaFileObject> diagnostics = new DiagnosticCollector<>();
StandardJavaFileManager fileManager = compiler.getStandardFileManager(diagnostics, null, null);
Iterable<? extends JavaFileObject> compilationUnits = fileManager.getJavaFileObjectsFromStrings(Arrays.asList("YouFileToCompile.java"));
JavaCompiler.CompilationTask task = compiler.getTask(null, fileManager, diagnostics, null,
null, compilationUnits);
boolean success = task.call();
fileManager.close();
4 Comments
Jeff Demanche
I tried this, and replaced the "YouFileToCompile.java" with an absolute path (problem?) now I get a NullPointerException at: StandardJavaFileManager fileManager = compiler.getStandardFileManager(diagnostics, null, null);
GETah
Sounds like the
compiler variable is null. Make sure you have a correct Java installation. Check this out for help java.net/node/688208
JD9999
Does it have to be a .java file? If I have code in a .txt file, will it still work?
JD9999
Also, if the code needs a dependency e.g. ASM, do I need to compile ASM with the app, or can I just have it in my main application?
The JavaCompiler will be null if the code is running from a JRE. It needs a JDK, which includes the tools.jar.