How to get compile error messages with JavaCompiler

Question

This is the code I am using to compile a java class:

public void javaCompile(String fileName) throws IOException {
    JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
    DiagnosticCollector<JavaFileObject> diagnostics = new DiagnosticCollector<JavaFileObject>();
    StandardJavaFileManager fileManager = compiler.getStandardFileManager(diagnostics, null, null);
    Iterable<? extends JavaFileObject> compilationUnits = fileManager
        .getJavaFileObjectsFromStrings(Arrays.asList(fileName));
    JavaCompiler.CompilationTask task = compiler.getTask(null, fileManager, diagnostics, null,
        null, compilationUnits);
    boolean success = task.call();
    fileManager.close();
    System.out.println("Success: " + success);
}

The problem is that I would like to receive more information about the errors that appear(more than Success: false). Can someone help me?

score 6 · Accepted Answer · answered Aug 30 '15 at 11:31

If you want just to print the errors in the console just don't use diagnosticsCollector, like following:

    public void javaCompile(String fileName) throws IOException {
        JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
//      DiagnosticCollector<JavaFileObject> diagnostics = new DiagnosticCollector<JavaFileObject>();
        StandardJavaFileManager fileManager = compiler.getStandardFileManager(null/*diagnostics*/, null, null);
        Iterable<? extends JavaFileObject> compilationUnits = fileManager
            .getJavaFileObjectsFromStrings(Arrays.asList(fileName));
        JavaCompiler.CompilationTask task = compiler.getTask(null, fileManager, null/*diagnostics*/, null,
            null, compilationUnits);
        boolean success = task.call();
        fileManager.close();
        System.out.println("Success: " + success);
    }

If you want to analyze errors programmatically use this:

public void javaCompile(String fileName) throws IOException {
    JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
    DiagnosticCollector<JavaFileObject> diagnosticsCollector = new DiagnosticCollector<JavaFileObject>();
    StandardJavaFileManager fileManager = compiler.getStandardFileManager(diagnosticsCollector, null, null);
    Iterable<? extends JavaFileObject> compilationUnits = fileManager.getJavaFileObjectsFromStrings(Arrays.asList(fileName));
    JavaCompiler.CompilationTask task = compiler.getTask(null, fileManager, diagnosticsCollector, null, null, compilationUnits);
    boolean success = task.call();
    if (!success) {
        List<Diagnostic<? extends JavaFileObject>> diagnostics = diagnosticsCollector.getDiagnostics();
        for (Diagnostic<? extends JavaFileObject> diagnostic : diagnostics) {
            // read error dertails from the diagnostic object
            System.out.println(diagnostic.getMessage(null));
        }
    }
    fileManager.close();
    System.out.println("Success: " + success);
}

In that case you should accept this answer by clicking the "tick" sign. — outdev, Aug 30 '15 at 17:48

How to get compile error messages with JavaCompiler

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