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Java 由字符串给出的类的编译_Java_Class_Exception_Compilation - Fatal编程技术网

Java 由字符串给出的类的编译

Java 由字符串给出的类的编译,java,class,exception,compilation,Java,Class,Exception,Compilation,我有以下代码: public static void compileClass() { JavaCompiler compiler = ToolProvider.getSystemJavaCompiler(); DiagnosticCollector<JavaFileObject> diagnostics = new DiagnosticCollector<>(); StringWriter writer = new StringWriter()

我有以下代码:

public static void compileClass() {
    JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
    DiagnosticCollector<JavaFileObject> diagnostics = new DiagnosticCollector<>();

    StringWriter writer = new StringWriter();
    PrintWriter out = new PrintWriter(writer);
    out.println("package ccc;");
    out.println("public class HelloWorld {");
    out.println("  public static void main(String args[]) {");
    out.println("    System.out.println(\"This is in another java file\");");
    out.println("  }");
    out.println("}");
    out.close();
    JavaFileObject file = new JavaSourceFromString("HelloWorld", writer.toString());

    Iterable<? extends JavaFileObject> compilationUnits = Arrays.asList(file);
    CompilationTask task = compiler.getTask(null, null, diagnostics, null, null, compilationUnits);

    boolean success = task.call();
    for (Diagnostic diagnostic : diagnostics.getDiagnostics()) {
        System.out.println(diagnostic.getCode());
        System.out.println(diagnostic.getKind());
        System.out.println(diagnostic.getPosition());
        System.out.println(diagnostic.getStartPosition());
        System.out.println(diagnostic.getEndPosition());
        System.out.println(diagnostic.getSource());
        System.out.println(diagnostic.getMessage(null));

    }
    System.out.println("Success: " + success);

    if (success) {
        try {
            Class.forName("ccc.HelloWorld").getDeclaredMethod("main", new Class[]{String[].class})
                    .invoke(null, new Object[]{null});
        } catch (ClassNotFoundException e) {
            System.err.println("Class not found: " + e);
        } catch (NoSuchMethodException e) {
            System.err.println("No such method: " + e);
        } catch (IllegalAccessException e) {
            System.err.println("Illegal access: " + e);
        } catch (InvocationTargetException e) {
            System.err.println("Invocation target: " + e);
        }
    }
}
问题:当运行method compileClass时,所有内容都很清楚,但不一致:

Class.forName("ccc.HelloWorld").getDeclaredMethod("main", new Class[]{String[].class})
                    .invoke(null, new Object[]{null});
将引发异常:

未找到类:java.lang.ClassNotFoundException:ccc.HelloWorld


该类已编译,但未添加到当前java应用程序的类路径中。您不应该将ccc.HelloWorld传递给JavaSourceFromString而不仅仅是HelloWorld吗?@SotiriosDelimanolis那么,您能告诉我解决方案是什么吗?可以通过编程方式完成吗?
Class.forName("ccc.HelloWorld").getDeclaredMethod("main", new Class[]{String[].class})
                    .invoke(null, new Object[]{null});