Compiling and Executing Code From a String in Java

Compiling and Executing Code From a String in Java

The idea of compiling and executing code from a string in Java may be daunting, but it is possible and can prove quite useful. With the help of some libraries and a few lines of code, you can easily load, compile, and execute Java code stored in a string. By following this guide, writing and executing code from a string in Java will be quick and easy!

How to Compile and Execute Code From a String in Java?

To compile and execute code from a string in Java, you will need the following additional libraries:

• Commons IO
• Commons Lang
• Java Compiler API

Once you have the necessary libraries, you can start writing your code. Below is an example of a method that compiles and executes code from a string in Java:

public static void compileAndExecute(String code){
    // Create a Java compiler
    JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();

    // Create a file manager
    StandardJavaFileManager fileManager = compiler.getStandardFileManager(null, null, null);

    // Get the code in a string and convert it to a File object
    File sourceFile = new File("source.java");
    Files.write(sourceFile.toPath(),   code.getBytes());

    // Compile the code
    boolean success = compiler.getTask(null,fileManager,null,null,null,fileManager.getJavaFileObjects(sourceFile)).call();

    // If the compilation was successful, execute the code
    if (success) {
        Class<?> aClass = new URLClassLoader(new URL[]{sourceFile.toURI().toURL()},Main.class.getClassLoader()).loadClass("Test");
        aClass.getDeclaredMethod("execute").invoke(null);
    }
}

The above method will take a String as input, use the Java Compiler API to compile the code, and then execute it. The method should work for any valid Java code.

Conclusion

Compiling and executing code from a string in Java is not only possible but also quite easy. By following the steps outlined in this guide, you should have no trouble setting up a working system that can compile and execute Java code from a string.