Iterator for 2-D Array

Set up a iterator to iterate a 2-dimensional array. By given the following code, finish all class:

public class DeepIterator{

    public DeepIterator(int[][] listOfLists){
        ...
    }

    ...
    public static void main(String[] args) {
        int[][] listOfLists = {
          {},{},{1,2,3},{},{},{2,3,4}
        };
        DeepIterator it = new DeepIterator(listOfLists);
        while(it.hasNext()){
            System.out.println(it.next());
        }
    }
}

Think

• Iterate the 2-D array by x and y.
• Record current element during hasNext() function.
• Check the row if it is null.

Solution

public class DeepIterator{
    int cur; // this is important
    int row = 0, col = 0;

    int[][] listOfLists;

    public DeepIterator(int[][] listOfLists){
        if(listOfLists == null)
            throw new IllegalArgumentException("Null Input");
        this.listOfLists = listOfLists;
    }

    public Integer next(){
        return cur;
    }

    public boolean hasNext(){
        // make sure the row is not null
        while(row < listOfLists.length && col >= listOfLists[row].length) {
                row ++; col = 0;
        }
        if(row < listOfLists.length) {
            cur = listOfLists[row][col++];
            return true;
        }else
            return false;
    }

    public static void main(String[] args) {
        int[][] listOfLists = {
          {},{},{1,2,3},{},{},{2,3,4}
        };
        DeepIterator it = new DeepIterator(listOfLists);
        while(it.hasNext()){
          System.out.println(it.next());
        }
    }
}