class HelloWorld(){
public helloWorld(){
System.out.println("Hello World");
}

public static void main(String[] args){
HelloWorld hw = new HelloWorld();
hw.helloWorld();
}
}

//Add logger aspect
aspect LogAspect(){
pointcut logMethod():
execution(public HelloWorld.helloWorld());
before():log(){
System.out.println("Before call");
}
}

Run without AspectJ:
Hello World

Run with AspectJ:
Before call
Hello World