Create hello world by asm tool

ExampleUnitTest.java

public class ExampleUnitTest {

    @Test
    public void helloWorldByAsm() {
        ClassWriter cw = new ClassWriter(0);
        cw.visit(V1_8, ACC_PUBLIC, "Hello", null, "java/lang/Object", null);
        MethodVisitor mv = cw.visitMethod(ACC_PUBLIC + ACC_STATIC,
                "main", "([Ljava/lang/String;)V", null, null);
        mv.visitFieldInsn(GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;");
        mv.visitLdcInsn("Hello, World");
        mv.visitMethodInsn(INVOKEVIRTUAL, "java/io/PrintStream",
                "println", "(Ljava/lang/String;)V", false);
        mv.visitInsn(RETURN);
        mv.visitMaxs(2, 1);
        mv.visitEnd();
        cw.visitEnd();

        MyClassLoader classLoader = new MyClassLoader();
        Class<?> clazz = classLoader.defineClass("Hello", cw.toByteArray());
        try {
            Method main = clazz.getMethod("main", String[].class);
            main.invoke(null, new Object[] { new String[] {} });
        } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException e) {
            e.printStackTrace();
        }
    }

    private static class MyClassLoader extends ClassLoader {

        public Class<?> defineClass(String name, byte[] b) {
            return super.defineClass(name, b, 0, b.length);
        }
    }
}