#vulnerable code 
                                @Override
    public void setV(int i, int f, float nextVif) {
        assert (i >= 1) : i;
        float[] vi = _V.get(i);
        vi[f] = nextVif;
    } 
                            #location 5 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Override
    public void setV(int i, int f, float nextVif) {
        assert (i >= 0) : i;
        float[] vi = _V.get(i);
        assert (vi != null) : "V[" + i + "] was null";
        vi[f] = nextVif;
    }