import org.objectweb.asm.*; public class HelloWorldGenerator { public static void main(String[] args) throws Exception { ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES); cw.visit(Opcodes.V1_8, Opcodes.ACC_PUBLIC, "HelloWorld", null, "java/lang/Object", null); MethodVisitor mv = cw.visitMethod(Opcodes.ACC_PUBLIC + Opcodes.ACC_STATIC, "main", "([Ljava/lang/String;)V", null, null); mv.visitFieldInsn(Opcodes.GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;"); mv.visitLdcInsn("Hello, World!"); mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V", false); mv.visitInsn(Opcodes.RETURN); mv.visitMaxs(0, 0); mv.visitEnd(); byte[] bytecode = cw.toByteArray(); ClassLoader cl = new ClassLoader() { public Class<?> defineClass(String name, byte[] bytes) { return defineClass(name, bytes, 0, bytes.length); } }; Class<?> helloWorldClass = cl.defineClass("HelloWorld", bytecode); helloWorldClass.getMethod("main", String[].class).invoke(null, (Object) new String[] {}); } }


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