Java String.split() Regex

java regex string split

300,978

Solution 1

String[] ops = str.split("\\s*[a-zA-Z]+\\s*");
String[] notops = str.split("\\s*[^a-zA-Z]+\\s*");
String[] res = new String[ops.length+notops.length-1];
for(int i=0; i<res.length; i++) res[i] = i%2==0 ? notops[i/2] : ops[i/2+1];

This should do it. Everything nicely stored in res.

Solution 2

str.split (" ") 
res27: Array[java.lang.String] = Array(a, +, b, -, c, *, d, /, e, <, f, >, g, >=, h, <=, i, ==, j)

Solution 3

    String str = "a + b - c * d / e < f > g >= h <= i == j";
    String reg = "\\s*[a-zA-Z]+";

    String[] res = str.split(reg);
    for (String out : res) {
        if (!"".equals(out)) {
            System.out.print(out);
        }
    }

Output : + - * / < > >= <= ==

Solution 4

You could split on a word boundary with \b

View more solutions

300,978

Author by

user677786

Updated on July 09, 2022

Comments

user677786 almost 2 years

I have a string:

String str = "a + b - c * d / e < f > g >= h <= i == j";

I want to split the string on all of the operators, but include the operators in the array, so the resulting array looks like:

[a , +,  b , -,  c , *,  d , /,  e , <,  f , >,  g , >=,  h , <=,  i , ==,  j]

I've got this currently:

public static void main(String[] args) {
    String str = "a + b - c * d / e < f > g >= h <= i == j";
    String reg = "((?<=[<=|>=|==|\\+|\\*|\\-|<|>|/|=])|(?=[<=|>=|==|\\+|\\*|\\-|<|>|/|=]))";

    String[] res = str.split(reg);
    System.out.println(Arrays.toString(res));
}

This is pretty close, it gives:

[a , +,  b , -,  c , *,  d , /,  e , <,  f , >,  g , >, =,  h , <, =,  i , =, =,  j]

Is there something I can do to this to make the multiple character operators appear in the array like I want them to?

And as a secondary question that isn't nearly as important, is there a way in the regex to trim the whitespace off from around the letters?

tchrist about 12 years

Did you try it? You’re going to have a problem.
Andrew Morton about 12 years

OK, I admit it, I tested it in .NET and it worked. Removing the empty entries should be trivial, and removing the spaces in the string is surely easily accomplished with a .replaceAll before applying the Regex.
user677786 about 12 years

While not the exact solution, it did give me the idea that worked! Thanks! I'll edit the main post for the solution!
Chris White about 12 years

Yeap, this works, just strip off the leading element from the array (which is empty)
user677786 about 12 years

After coming back, this seems like the best way to do it. I'd like to have done it in the regex, but this will work perfectly. Thanks!
ghosh about 5 years

Any explanation?