android - SetImageResource のランダム値が機能しない

Question

関数で RANDOM 値を取得したいのですが、n は常に 0 です。何が間違っていますか?

    image = (ImageView) findViewById(R.id.imageView1);
    //блок Random
    Log.d(Tag, "1");
    int NUM_IMAGES=7;
    int imageArr[] = new int[NUM_IMAGES];
    Log.d(Tag, "2");
    imageArr[0] = R.drawable.image1;
    imageArr[1] = R.drawable.image2;
    imageArr[2] = R.drawable.image3;
    imageArr[3] = R.drawable.image4;
    imageArr[4] = R.drawable.image5;
    imageArr[5] = R.drawable.image6;
    imageArr[6] = R.drawable.image7;

    Log.d(Tag, "3");
    int n = (int)Math.random()*NUM_IMAGES;
    Log.d(Tag, "n="+n);
    image.setImageResource(imageArr[n]);