Question

public class BusInformation {

String BusRoute[][] = new String[4][];

BusRoute[0] = new String[] {"a" , "b", "c"};

BusRoute[1] = new String[] {"a" , "b"};
}

I know how many BusRoutes are there as in first parameter. The second parameters size is variable and depends on the route.
How can I initialize it this way?

Answer 1

You should be able to code it like this…

public class BusInformation {
    String busRoute[][] = new String[4][0];

    public BusInformation(){
        busRoute[0] = new String[] {"a" , "b", "c"};
        busRoute[1] = new String[] {"a" , "b"};
    }
}

Its the same as your code, but like to specify an initial size of 0 for the second dimension, just so its clear that it doesn’t have any initial size. I also wrapped the loading of the array into the class constructor.

A 2D array is just a normal 1D array where each item is an array of any length. Even if you set the 2D array at an initial size, such as new String[4][5], it won’t make any difference – you can still assign smaller or larger arrays to each item of the base array, just as you are doing already.