Question

Can someone tell me why this code has a hole at: array[0][4]?

public class Random{ 

    public static void main (String []args){

        String [][] array={{"This is a test. A hole here"}};

        for(int i=0;i<array.length;i++){
            String temp=array[i][0];

            array[i]=temp.split("[\\:., ]");
        }

        System.out.print(array[0][4]);
    }
}

Yet, when I add a plus sign to the delimiters(“[\:., ]+”), I get the correct output.

public class Random{ 

    public static void main (String []args){

        String [][] array={{"This is a test. A hole here"}};

        for(int i=0;i<array.length;i++){
            String temp=array[i][0];
            array[i]=temp.split("[\\:., ]+");
        }

        System.out.print(array[0][4]);
    }
}

Is there a reason why the plus sign removes this hole and solve this problem? I am open to any suggestions or comments. Yes, I am a novice.

Answer 1

With array[i]=temp.split("[\\:., ]"); your string is splitted here:

This is a test. A hole here
    ^  ^ ^    ^^ ^    ^

So you get an empty string at array[4].

With array[i]=temp.split("[\\:., ]+"); it will combine “. ” into one “split point” and because of that it will not split in between.