How to get the build/version number of your Android application?

Question

I need to figure out how to get or make a build number for my Android application. I need the build number to display in the UI.

Do I have to do something with

Answer 1

private String GetAppVersion(){
        try {
            PackageInfo _info = mContext.getPackageManager().getPackageInfo(mContext.getPackageName(), 0);
            return _info.versionName;
        } catch (PackageManager.NameNotFoundException e) {
            e.printStackTrace();
            return "";
        }
    }

    private int GetVersionCode(){
        try {
            PackageInfo _info = mContext.getPackageManager().getPackageInfo(mContext.getPackageName(), 0);
            return _info.versionCode;
        } catch (PackageManager.NameNotFoundException e) {
            e.printStackTrace();
            return -1;
        }
    }