Spacing in a GridView

I have in my android project a gridview that I define as follows: I created an XML Adapter, so the gridview cuts some letters (icons), as it represents the image below. As I started developing now, I do not know about the properties of gridview. Note: I followed this tutorial: link

import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;

public class ImageAdapter extends BaseAdapter {
private Context mContext;

public ImageAdapter(Context c) {
    mContext = c;
}

public int getCount() {
    return mThumbIds.length;
}

public Object getItem(int position) {
    return null;
}

public long getItemId(int position) {
    return 0;
}

// create a new ImageView for each item referenced by the Adapter
public View getView(int position, View convertView, ViewGroup parent) {
    ImageView imageView;
    if (convertView == null) {
        // if it's not recycled, initialize some attributes
        imageView = new ImageView(mContext);
        imageView.setLayoutParams(new GridView.LayoutParams(85, 85));
        imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
        imageView.setPadding(8, 8, 8, 8);
    } else {
        imageView = (ImageView) convertView;
    }

    imageView.setImageResource(mThumbIds[position]);
    return imageView;
}

// references to our images

private Integer[] mThumbIds = {
        R.drawable.a, R.drawable.n,
        R.drawable.b, R.drawable.o,
        R.drawable.c, R.drawable.p,
        R.drawable.d, R.drawable.q,
        R.drawable.e, R.drawable.r,
        R.drawable.f, R.drawable.s,
        R.drawable.g, R.drawable.t,
        R.drawable.h, R.drawable.u,
        R.drawable.i, R.drawable.v,
        R.drawable.j, R.drawable.w,
        R.drawable.k, R.drawable.x,
        R.drawable.l, R.drawable.y,
        R.drawable.m, R.drawable.z
};

}