Have anyone tried this tutorial ?

[Q-ro]

Hello everyone, i'm trying to follow the tutorials for a camera app located in ; the problem is that when i try and copy paste to my project, i get an error showing there is something wrong int he following code:

public void surfaceCreated(SurfaceHolder holder) {
        // The Surface has been created, now tell the camera where to draw the preview.
        try {
            mCamera.setPreviewDisplay(holder);
            mCamera.startPreview();
        } catch (IOException e) {
            Log.d(TAG, "Error setting camera preview: " + e.getMessage());
        }
    }

the error goes something like "TAG variable is not set", but, as far as i understood, TAG is some sort of internal class/function on the Android API, so, ¿ is there something i'm missing ?.

Thanks in advance.