Add ProcessPidCallback to cancel a specific download

[HsuHsiaoHsuan]

I'm using this lib in our project and I need to find a way to cancel a specific download progress,
this is how I achieve this purpose.

https://play.google.com/store/apps/details?id=cc.ytmp3.gp

[JunkFood02]

The idea looks good. But in my opinion, letting the library itself manage the process(es) and call Process.destroy() could be a neater option.

[xibr]

Does it work on this method!

VideoInfo streamInfo = YoutubeDL.getInstance().getInfo("https://vimeo.com/22439234");
System.out.println(streamInfo.getTitle());

2022-08-06 19:01:39.165 7997-7997/com.yausername.youtubedl_android_example E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.yausername.youtubedl_android_example, PID: 7997
    java.lang.NullPointerException: Attempt to invoke interface method 'void com.yausername.youtubedl_android.ProcessPidCallback.onProcessRun(java.lang.String)' on a null object reference
        at com.yausername.youtubedl_android.YoutubeDL.execute(YoutubeDL.java:186)
        at com.yausername.youtubedl_android.YoutubeDL.getInfo(YoutubeDL.java:128)
        at com.yausername.youtubedl_android.YoutubeDL.getInfo(YoutubeDL.java:122)
        at com.yausername.youtubedl_android_example.DownloadingExampleActivity.startDownload(DownloadingExampleActivity.java:133)
        at com.yausername.youtubedl_android_example.DownloadingExampleActivity.onClick(DownloadingExampleActivity.java:99)
        at android.view.View.performClick(View.java:7352)
        at android.widget.TextView.performClick(TextView.java:14230)
        at android.view.View.performClickInternal(View.java:7318)
        at android.view.View.access$3200(View.java:846)
        at android.view.View$PerformClick.run(View.java:27800)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7050)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:494)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:965)

[JunkFood02]

Instead of exposing the pid directly to the outside caller, my solution is that the caller manually specifies an id and then stores the key-value pair of the Process and the id in a Map. In this way, we can manage all processes more effectively and have more control through the methods provided by java.lang.Process.

[xibr]

Instead of exposing the pid directly to the outside caller, my solution is that the caller manually specifies an id and then stores the key-value pair of the Process and the id in a Map. In this way, we can manage all processes more effectively and have more control through the methods provided by java.lang.Process.

Your solution may be better.

[p3g4asus]

You need to check pidCallback for nullity. Otherwise java will throw NullPointerException when pidCallback is not specified.

[p3g4asus]

Please check this #173

[HsuHsiaoHsuan]

Thanks all reviews and suggestions!