Boundary traversal of matrix

//User function Template for Java

class Solution
{
    //Function to return list of integers that form the boundary 
    //traversal of the matrix in a clockwise manner.
    static ArrayList<Integer> boundaryTraversal(int matrix[][], int n, int m)
    {
        // code here 
        
        
        ArrayList<Integer> result = new ArrayList<Integer>();
        
        if(n == 1)
        {
            int i = 0;
            while(i < m)
            {
                result.add(matrix[0][i++]);
            }
        }
        else if(m == 1)
        {
            int i = 0;
            while(i < n)
            {
                result.add(matrix[i++][0]);
            }
        }
        else
        {   
            
            for(int j=0;j<m;j++)
            {
                result.add(matrix[0][j]);
            }
          
            for(int j=1;j<n;j++)
            {    
                result.add(matrix[j][m-1]);
                
            }
          
            for(int j=m-2;j>=0;j--)
            {    
                result.add(matrix[n-1][j]);
            }            
          
            for(int j=n-2;j>=1;j--)
            {    
                result.add(matrix[j][0]);
            }
            
        }   
      
        return result; 
    }
}