48. Rotate Image via java

need to use scratch to find the pattern

class Solution {
    public void rotate(int[][] matrix) {
    int n=matrix.length;
    for (int i=0; i<n/2; i++)
        for (int j=i; j<n-i-1; j++) {
            int tmp=matrix[i][j];
            matrix[i][j]=matrix[n-j-1][i];
            matrix[n-j-1][i]=matrix[n-i-1][n-j-1];
            matrix[n-i-1][n-j-1]=matrix[j][n-i-1];
            matrix[j][n-i-1]=tmp;
        }
        return;}
}