JavaCompiler gives error when dependent class is being created

Question

I writed a code that generates two class which I write them to buffer and compile them with JavaCompiler. My classes are like this in .java files;

public class A{
    public A() { }
    public String toString(){ return "A";}
    }

and

public class B extends ArrayList<A> {
public B() {
    super();
}

public void addItem(A a) 
{
    this.add(a);
}

public void print() {
    this.print();
    }
}

something like this.

However, the name of the classes are randomly generated and when I create the file it gives an error like this;

symbol:   class A
location: class B  

./src/A.java:4: error: cannot find symbol

(4th line is the "...extends ArrayList..." and there is a ^ symbol under A)

My code generator compiles like this;

First I fill the buffer with my template for A type classes then compile like this:

JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
compiler.run(null, null, null, f.getPath());

after that I create another buffer and fill it with my template for B type classes then compile like this;

System.out.println(f.getParentFile().getPath());
compiler.run(null, null, null, f.getPath());

f is;

f = new File(("./src/" + name + ".java"));

How can I solve this problem?

Answer 1

this should be help

    public void CompileClasses(ArrayList<String> classesNames){
    //File helloWorldJava = new File("classes\\"+className+".java");
    try {
        List<String> optionList = new ArrayList<String>();
        optionList.add("-classpath");
        optionList.add(System.getProperty("java.class.path") + ";dist/InlineCompiler.jar");
        DiagnosticCollector<JavaFileObject> diagnostics = new DiagnosticCollector<JavaFileObject>();
        JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
        StandardJavaFileManager fileManager = compiler.getStandardFileManager(diagnostics, null, null);
        Iterable<? extends JavaFileObject> compilationUnit=null;
        ArrayList<File> files = new ArrayList<>();
        for (String className:classesNames) {
        files.add(new File(className+".java"));
        }
        compilationUnit = fileManager.getJavaFileObjectsFromFiles(files);
        JavaCompiler.CompilationTask task = compiler.getTask(
                null,
                fileManager,
                diagnostics,
                optionList,
                null,
                compilationUnit);
        if (task.call()) {
            URLClassLoader classLoader = new URLClassLoader(new URL[]{new File("./").toURI().toURL()});
        } else {
            for (Diagnostic<? extends JavaFileObject> diagnostic : diagnostics.getDiagnostics()) {
                System.out.format("Error on line %d in %s%n %s",
                        diagnostic.getLineNumber(),
                        diagnostic.getSource().toUri(),
                        diagnostic.toString());
            }
        }
        fileManager.close();
    } catch (IOException exp) {
        exp.printStackTrace();
    }

}

Answer 2

As mentioned in the comment the compiler need to know about class A when class B is compiled. In the example below we add the output directory for the compiled classes /tmp/bin/ to the classpath for the compiler in optionList.

You could either prevent to create the source files on the filesystem, if you don't need them as such

public class CompileDependent {

    public static void main(String[] args) {
        String sourceClassA = "public class A {"
                + "  public String toString() {"
                + "    return \"A\";"
                + "  }"
                + "}";
        String sourceClassB = "import java.util.ArrayList;"
                + "class B extends ArrayList<A> {"
                + "  public void addItem(A a) {"
                + "    this.add(a);"
                + "  }"
                + "}";

        List<JavaFileObject> compilationUnits = new ArrayList<>();
        compilationUnits.add(new StringJavaFileObject("A.java", sourceClassA));
        compilationUnits.add(new StringJavaFileObject("B.java", sourceClassB));

        List<String> optionList = new ArrayList<>();
        // classpath from current JVM + binary output directory
        optionList.add("-classpath");
        optionList.add(System.getProperty("java.class.path") + ":/tmp/bin");
        // class output directory
        optionList.add("-d");
        optionList.add("/tmp/bin");

        JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
        StandardJavaFileManager fileManager = compiler.getStandardFileManager(
                null,
                Locale.UK,
                Charset.forName("UTF-8")
        );

        boolean compiled = compiler.getTask(
                null,
                fileManager,
                null,
                optionList,
                null,
                compilationUnits).call();
        System.out.println("compiled = " + compiled);
    }

    private static class StringJavaFileObject extends SimpleJavaFileObject {

        final String code;

        StringJavaFileObject(String name, String code) {
            super(URI.create("string:///" + name), Kind.SOURCE);
            this.code = code;
        }

        @Override
        public CharSequence getCharContent(boolean ignoreEncodingErrors) {
            return code;
        }
    }
}

or you create the Java source files on the file system. Similar code as above with a small change for the compilationUnits. It's assumed the files have been already stored on the given location.

List<File> sourceFiles = new ArrayList<>();
sourceFiles.add(new File("/tmp/A.java"));
sourceFiles.add(new File("/tmp/B.java"));