Split string in java based on integer delimeter

Question

I'm trying to split a couple of strings based on the integer that's in the based, while still retaining the integer.

String theMessage = "1. First String. 2. Second String. 10. Tenth String. 20. Twentieth String.";
String delims = "(?<=(0*([0-9]{1,2}|100)))";
String[] questions = theMessage.split(delims);  
System.out.println(Arrays.toString(questions));

But it separates them as:

1. First String. 2 
 . Second String. 1 
1 
0 
 . Tenth String. 2 
0 \n
 . Twentieth String 

But I want them to be separated like this:

1. First String.
2. Second String.
10. Tenth String.
20. Twentieth String.

Basically I want each separated portion to be a different element in an array.

Answer 1

You can split on whitespace preceding your integers, resulting each group as an array element.

String s = "1. First String. 2. Second String. 10. Tenth String. 20. Twentieth String.";
String[] parts = s.split("\\s+(?=[0-9])");
System.out.println(Arrays.toString(parts));

See Live demo

Output

[1. First String., 2. Second String., 10. Tenth String., 20. Twentieth String.]

Answer 2

The following works so long as you can never have digits within the strings.

String numberedString = "1. First String. 2. Second String. 10. Tenth String. 20. Twentieth String.";
Pattern numberedStringPattern = Pattern.compile("([0-9]+)\\.([^0-9]+)");
Matcher numberedStringMatcher = numberedStringPattern.matcher(
        numberedString);

while(numberedStringMatcher.find()) {
    System.out.println("Found string "+numberedStringMatcher.group(
            1)+" with value \""+numberedStringMatcher.group(2)+"\"");
}

This code gives the output:

Found string 1 with value " First String. "
Found string 2 with value " Second String. "
Found string 10 with value " Tenth String. "
Found string 20 with value " Twentieth String."

So you will probably want to use trim() to remove the whitespace at the start and end of the returned String values.