java - Saving a vector in another vector and clearing the first one -

i have technical issue in coding. below defining vector of vectors:

        vector<vector<integer>> usupvec = new vector<vector<integer>>();         vector<integer> usup = new vector<integer>();         boolean isrep = false;         (int = 1; <numsup ; i++) {             usup.clear();             (int l = 0; l < i; l++) {                 if (supname[i] == supname[l]) {                     isrep = true;                 }}             if (!isrep){usup.add(i);}                    (int j = i+1; j < numsup; j++) {                 if (supname[i] == supname[j]) {                         if (!isrep){usup.add(j);}                         }}             isrep = false;             usupvec.add((vector) usup);         } 

my problem whenever clearing usup vector, vectors stored in usupvec cleared. in each iteration want define vector of integer numbers , store in vector of vectors , clear vector store new values , store again in vector of vectors.

modify

usupvec.add((vector) usup); 

to

usupvec.add(new vector(usup));