finding all subsets of a given set in java and in this order

actually i want to write all subsets of a given set in this way :

for example if my set is A:{1,2} i want to have {} , {1} , {2} , {1,2}

this is what i tried :

static void printSubsets(java.util.Set<Integer> a) {
        int n = a.size();
        // Run a loop for printing all 2^n
        // subset one by one
        for (int i = 0; i < (1 << n); i++) {
            System.out.print("{");
            // Print current subset
            for (int j = 0; j < n; j++) {

                // (1<<j) is a number with jth bit 1
                // so when we 'and' them with the
                // subset number we get which numbers
                // are present in the subset and which
                // are not
                if ((i & (1 << j)) > 0)
                    System.out.print(a.toArray()[j] + ",");
                if (j == n - 1)
                   System.out.print(a.toArray()[j]);
            }
            System.out.print("} , ");
        }
    }

and this is the out put {} , {1,} , {2,} , {1,2,} , my problem is with , . i do not want to have , at the end of every subset and at the end of the whole output can you help me solve this problem to have a output like {} , {1} , {2} , {1,2}