如何在顶部的 if 中使用 sp 变量？

Question

I am working on a Minecraft Bukkit plugin, using this API. The problem I'm having is that I want to use the sp variable in the code below, to check if it is playing using .isplaying() (a method of the API), in the if-statement at the top. The problem is, is that the sp variable is created inside the if-statement. So how can I use that sp variable in the if-statement when the method is ran again?

If I'm not clear enough, tell me. Also I'm pretty new to java, so bear that in mind.

-JustRamon

public void playTune(String eventTune, Player p)
{
    if (Methods.getSongPath(eventTune).exists()) //&& sp.isplaying()
    {
            Song s = NBSDecoder.parse(Methods.getSongPath(eventTune));
            SongPlayer sp = new RadioSongPlayer(s);
            sp.setAutoDestroy(true);
            sp.addPlayer(p);
            sp.setPlaying(true);
    }
    else
    {
            notFound(eventTune);
    }
}

Answer 1

First of all, if you want to access the object with multiple calls to your method, you want a reference to the object. So you should declare a variable inside your class like so:

private SongPlayer sp; 

Then change your method as follows:

public void playTune(String eventTune, Player p)
{
    /*Creates sp if it is null (When it is null, we know that there is no
    RadioSongPlayer object referenced by sp)*/
    if (Methods.getSongPath(eventTune).exists()) && sp == null)
    {
            Song s = NBSDecoder.parse(Methods.getSongPath(eventTune));
            sp = new RadioSongPlayer(s);
            sp.setAutoDestroy(true);
            sp.addPlayer(p);
            sp.setPlaying(true);
    }
    else
    {
            notFound(eventTune);
    }
    //Now that sp is not null, we know that it references a SongPlayer object, that is,
    //the object we just created in the first if statement
    if(sp != null){ /
        //sp was created
        //Use sp
    }
}

I won't recommend you to do this tho. It will be better to refactor your first if to another method because creating a SongPlayer shouldn't be a concern of your playTune method.