Java reflect, edit code in runtime

i am currently trying to edit a class file in runtime, example:

Example.java with this code:

public static void execute(){
System.out.println("hello worl");
}

there is no esey way to edit the text in this example, now i need code that edits the "hello worl" to "hello world" without having acces to the Example.java and without restarting the programm to edit bytecode, is this possible? I have serched meny articels and haven found a defined anser