how to create an array of arraylist in java

// Java code to demonstrate the concept of  
// array of ArrayList 
  
import java.util.*; 
public class Arraylist { 
    public static void main(String[] args) 
    { 
        int n = 5; 
  
        // Here al is an array of arraylist having 
        // n number of rows.The number of columns on 
        // each row depends on the user. 
        // al[i].size() will give the size of the 
        // i'th row 
        ArrayList<Integer>[] al = new ArrayList[n]; 
  
        // initializing 
        for (int i = 0; i < n; i++) { 
            al[i] = new ArrayList<Integer>(); 
        } 
  
        // We can add any number of columns to each 
        // rows as per our wish 
        al[0].add(1); 
        al[0].add(2); 
        al[1].add(5); 
        al[2].add(10); 
        al[2].add(20); 
        al[2].add(30); 
        al[3].add(56); 
        al[4].add(34); 
        al[4].add(67); 
        al[4].add(89); 
        al[4].add(12); 
  
        for (int i = 0; i < n; i++) { 
            for (int j = 0; j < al[i].size(); j++) { 
                System.out.print(al[i].get(j) + " "); 
            } 
            System.out.println(); 
        } 
    } 
} 
ArrayList<String> a = new ArrayList<>( Arrays.asList(oldArray));