performance of int Array vs Integer Array

Today when I submitted a solution to codeforces, I used int[] array and my submission got TLE(Time limit exceeded) & after changing it to Integer[] array surprisingly it got AC. I didn't get how the performance is improved.

import java.io.*;
import java.lang.reflect.Array;
import java.util.*;

public class Main {
    static class Task {
        public void solve(InputReader in, PrintWriter out) throws Exception {
            int n = in.nextInt();
            Integer[] a = new Integer[n];
            for (int i = 0; i < n; i++) a[i] = in.nextInt();
            Arrays.sort(a);
            long count = 0;
            for (int i = 0; i < n; i++) count += Math.abs(i + 1 - a[i]);
            out.println(count);
        }
    }

    public static void main(String[] args) throws Exception{
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task task = new Task();
        task.solve(in, out);
        out.close();
    }


    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
}