Getting TLE in codechef problem https://www.codechef.com/START1C/problems/ADMIT

#1

I am getting TLE for this problem https://www.codechef.com/START1C/problems/ADMIT
Below is my code. can anyone help me out?

I Have added few comments to explain my approach.

class CollegeAdmission {
public static void main(String[] args) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
PrintWriter pw = new PrintWriter(new OutputStreamWriter(System.out));
StringTokenizer st;
int T = Integer.parseInt(br.readLine());
while(T–>0) {
st = new StringTokenizer(br.readLine());
int n = Integer.parseInt(st.nextToken());
int m = Integer.parseInt(st.nextToken());
int[] collegeRank = new int[n];
st = new StringTokenizer(br.readLine());
for(int i=0; i<n; i++)
collegeRank[i] = Integer.parseInt(st.nextToken());

        int[] studentRank = new int[m];
        st = new StringTokenizer(br.readLine());
        for(int i=0; i<m; i++)
            studentRank[i] = Integer.parseInt(st.nextToken());
        // List of List of college preference of students
        ArrayList<ArrayList<Integer>> preferences = new ArrayList<>(m);
        for(int i=0; i<m; i++) {
            st = new StringTokenizer(br.readLine());
            int k = Integer.parseInt(st.nextToken());
            // List of preference of particular student
            ArrayList<Integer> preference = new ArrayList<>(k);
            for(int j=0; j<k; j++)
                preference.add(Integer.parseInt(st.nextToken()) - 1); // minus 1 to match zero based indexing of college Id
            //sorting preference of student based on college rank
            preference.sort(Comparator.comparingInt(e -> collegeRank[e]));
            preferences.add(preference);
        }
        pw.println(getCollege(n,m,collegeRank,studentRank,preferences));
    }
    pw.close();
}

private static int getCollege(int n, int m, int[] collegeRank, int[] studentRank, ArrayList<ArrayList> preferences) {
// Track if college is available
boolean[] isAvailable = new boolean[n];
Arrays.fill(isAvailable,true);

    // Sorting student Ids based on their rank
    Integer [] studIdByRank = new Integer[m];
    for(int i=0; i<m; i++)
        studIdByRank[i] = i;
    Arrays.sort(studIdByRank, Comparator.comparingInt(e -> studentRank[e]));
    int chefRank = studentRank[0];
    for(int i=0; i<m && studentRank[studIdByRank[i]] <= chefRank; i++) {
        int stud_id = studIdByRank[i];
        for(int j=0; j<preferences.get(stud_id).size(); j++) {
            int coll_id = preferences.get(stud_id).get(j);
            if(isAvailable[coll_id]){
                isAvailable[coll_id] = false;
                if(stud_id == 0)
                    return coll_id+1;
                break;
            }
        }
    }
    return 0;
}