package test;import java.io.File;import java.io.IOException;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.net.URL;import java.net.URLClassLoader;import java.nio.charset.StandardCharsets;import java.nio.file.Files;import javax.tools.JavaCompiler;import javax.tools.ToolProvider;public class SimpleRun {    public static void showCompile() {        // Prepare source somehow.        String source = "package test; public class Test { static { System.out.println(\"hello\"); } public Test() { System.out.println(\"world\");} public void Hello(){System.out.println(\"fuck\");} }";        // Save source in .java file.        File root = new File("~/temp"); // On Windows running on C:\, this is                                        // C:\java.        File sourceFile = new File(root, "test/Test.java");        sourceFile.getParentFile().mkdirs();        try {            Files.write(sourceFile.toPath(), source.getBytes(StandardCharsets.UTF_8));            // Compile source file.            JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();            int success = compiler.run(null, null, null, sourceFile.getPath());            if (success == 0) {                // Load and instantiate compiled class.                URLClassLoader classLoader = URLClassLoader.newInstance(new URL[] { root.toURI().toURL() });                Class<?> cls;                try {                    // Should print "hello".                    cls = Class.forName("test.Test", true, classLoader);                    // Should print "world".                    Object instance = cls.newInstance();                    // Should print "test.Test@hashcode".                    System.out.println(instance);                    Method m = cls.getMethod("Hello", new Class<?>[] {});                    System.out.println(m);                    m.invoke(instance, new Object[]{});                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException e) {                    e.printStackTrace();                } catch (NoSuchMethodException e) {                    e.printStackTrace();                } catch (SecurityException e) {                    e.printStackTrace();                } catch (IllegalArgumentException e) {                    e.printStackTrace();                } catch (InvocationTargetException e) {                    e.printStackTrace();                }            } else {                System.out.println("compile failed");            }        } catch (IOException e) {            e.printStackTrace();        }    }    private static double calculate(String expr) {        String className = "Calculator";        String methodName = "calculate";        String source = "package test;  public class " + className + " { public static double " + methodName + "() { return " + expr                + "; } }";        // set work directory        File root = new File("~/temp");        // set work package        File sourceFile = new File(root, "test/Calculator.java");        sourceFile.getParentFile().mkdirs();        try {            Files.write(sourceFile.toPath(), source.getBytes(StandardCharsets.UTF_8));            // Compile source file.            JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();            int success = compiler.run(null, null, null, sourceFile.getPath());            if (success == 0) {                // Load and instantiate compiled class.                URLClassLoader classLoader = URLClassLoader.newInstance(new URL[] { root.toURI().toURL() });                Class<?> cls;                try {                    cls = Class.forName("test.Calculator", true, classLoader);                    Object instance = cls.newInstance();                    Method method = cls.getMethod(methodName, new Class<?>[] {});                    Object value = method.invoke(instance, new Object[] {});                    return (Double) value;                } catch (ClassNotFoundException | IllegalAccessException e) {                    e.printStackTrace();                } catch (NoSuchMethodException e) {                    e.printStackTrace();                } catch (SecurityException e) {                    e.printStackTrace();                } catch (IllegalArgumentException e) {                    e.printStackTrace();                } catch (InvocationTargetException e) {                    e.printStackTrace();                } catch (InstantiationException e) {                    e.printStackTrace();                }            } else {                System.out.println("compile failed");            }        } catch (IOException e) {            e.printStackTrace();        }        return 0.0;    }    public static void main(String[] args) {        SimpleRun.showCompile();        if (args.length >= 1) {            System.out.println(args[0] + "=" + SimpleRun.calculate(args[0]));        }    }}