Question

There is a

String temp = "M0-1"

How to convert this String to a String[] ?

If you output the new String array, the result should be:

String[] newStringArray;
newStringArray[0] = M;
newStringArray[1] = 0;
newStringArray[2] = -1;

The last element of the new String array should be “-1”, which means “-1” will be considered as a entirety, but not “-” and “1” separately.

I tried to use String.split(“”) parse this string, but only got a String array like this:

String[] newStringArray;
newStringArray[0] = M;
newStringArray[1] = 0;
newStringArray[2] = -;
newStringArray[3] = 1;

UPDATE: String 56 should be [5, 6], and -10 should be [-1, 0]

Answer 1

This split() will do it:

String[] array = temp.split("(?<=[^-])");

It works by splitting when the previous character is not a -

That odd-looking regex is called a look-behind. Its syntax is (?<=regex), which is a non-capturing assertion that the preceding input matches the specified regex, which in this case is [^-], which means “any character that isn’t a minus”.

There are 4 versions of this kind of assertion:

• (?=regex) is a positive look ahead, meaning the next input must match regex
• (?!regex) is a negative look ahead, meaning the next input must not match regex
• (?<=regex) is a positive look behind, meaning the preceeding input must match regex
• (?<!regex) is a negative look behind, meaning the nepreceedingxt input must not match regex

Here’s a test:

public static void main(String[] args) {
    String temp = "M0-1";
    String[] newStringArray = temp.split("(?<=[^-])");
    System.out.println(Arrays.toString(newStringArray));
}

Output:

[M, 0, -1]