java - 将 Runtime#exec() 与 javac 一起使用 - 无类文件

Question

以下 MyCompilingUtility.java 通过 PrintWriter 创建一个文件(Java 类 - AutoGenerate.java)。该类只有一个带有 print 语句的 Main 方法。其次，该程序调用javac AutoGenerate.java。

public static void main(String args[]) throws IOException, 
   FileNotFoundException, UnsupportedEncodingException {
    createFile("AutoGenerated.java");
    compile("AutoGenerated.java");
}

public static void compile(String fileName) throws IOException {
    final String javacPath = "C:/Program Files/Java/jdk1.7.0_51/bin/javac.exe";
    Runtime rt = Runtime.getRuntime();
    final String compileCmd = javacPath + " " + fileName;
    rt.exec(compileCmd);
}

public static void createFile(String fileName) throws FileNotFoundException,
       UnsupportedEncodingException  {
    PrintWriter writer = new PrintWriter(fileName, "UTF-8");
    writer.println("public class AutoGenerated");
    writer.println("{");
    writer.println("  public static void main(String [] args)");
    writer.println("  {");
    writer.println("    System.out.println(\"Hello from AutoGenerated World\")");
    writer.println("  }");
    writer.println("}");
    writer.close();
}

但是，运行javac MyCompilingUtility.java && java MyCompilingUtility后，没有生成AutoGenerate.class文件。

这是为什么？

Answer 1

您在

末尾缺少 ;

writer.println("    System.out.println(\"Hello from AutoGenerated World\");");
                                                                          ^

编译器根本无法编译它。