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Need help splitting the expression with regex

I have an expression like this.
A AND (B OR (C OR D))
I want the parentheses as a separate string and not combined with C OR D in the output array.
[A, AND, (, B, OR, (, C, OR, D, ), )]
Appending , in place of SPACE and after every ( and before every ) and then using .split(",") would solve my problem.
Is there any way better way to do this by simply using the right regex in the split method ?

How about this:
String input = "A AND (B OR (C OR D))";
String regex = "\\s+|(?<=\\()|(?=\\))";
String[] tokens = input.split(regex);
Which returns:
{A, AND, (, B, OR, (, C, OR, D, ), )}
Explanation:
The regex splits by
One or more spaces
Anything followed by a parenthesis
Anything preceded by a parenthesis
I used positive lookaheads and positive lookbehinds, which are INCREDIBLY useful, so do look them up (no pun intended)

I hope this would help:
"A AND (B OR (C OR D))".split(" +| (?=\\()|(?=\\))|(?<=\\()") #=> [A, AND, (, B, OR, (, C, OR, D, ), )]
+ # splits by whitespaces
(?=\\() # splits by whitespace followed by opening brace: e.g. in " (" it would give you single "(" instead of " " and "(" (like in the next part without whitespace in the beginning)
(?=\\)) # splits by empty string followed by closing brace: e.g. "B)" => ["B", ")"]
(?<=\\)) # splits by empty string preceding by closing brace: e.g. "))"
Search for "Positive lookahead/lookbehind" in regular expressions (personally I use regex101.com).

Splitting a String by number of delimiters

I am trying to split a string into a string array, there might be number of combinations,
I tried:
String strExample = "A, B";
//possible option are:
1. A,B
2. A, B
3. A , B
4. A ,B
String[] parts;
parts = strExample.split("/"); //Split the string but doesnt remove the space in between them so the 2 item in the string array is space and B ( B)
parts = strExample.split("/| ");
parts = strExample.split(",|\\s+");
Any guidance would be appreciated

To split with comma enclosed with optional whitespace chars you may use
s.split("\\s*,\\s*")
The \s*,\s* pattern matches
\s* - 0+ whitespaces
, - a comma
\s* - 0+ whitespaces
In case you want to make sure there are no leading/trailing spaces, consider trim()ming the string before splitting.

You can use
parts=strExample.split("\\s,\\s*");
for your case.

How to split a string by space and some special character in java

Consider the string .more opr (&x NE &m),&n+1
All i need is split this string into following parts .more,opr,(,&x,NE,&m,) , , , &n, +, 1.In short I need to split on spaces and some special symbols like ( ) , and arithmetic operators.
How to write regex expression for split() in java to achieve this.

Split on space or either side of brackets or operators:
str.split(" |(?<=[,()+-])|(?<! )(?=[,()+-])")
The output of:
String str = ".more opr (&x NE &m),&n+1";
System.out.println(Arrays.toString(str.split(" |(?<=[,()+-])|(?<! )(?=[,()+-])")));
is:
[.more, opr, (, &x, NE, &m, ), ,, &n, +, 1]
Or more clearly:
Arrays.stream(str.split(" |(?<=[,()+-])|(?<! )(?=[,()+-])")).forEach(System.out::println);
outputs:
.more
opr
(
&x
NE
&m
)
,
&n
+
1

Java replace strings between two commas

String = "9,3,5,*****,1,2,3"
I'd like to simply access "5", which is between two commas, and right before "*****"; then only replace this "5" to other value.
How could I do this in Java?

You can try using the following regex replacement:
String input = "9,3,5,*****,1,2,3";
input = input.replaceAll("[^,]*,\\*{5}", "X,*****");
Here is an explanation of the regex:
[^,]*, match any number of non-comma characters, followed by one comma
\\*{5} followed by five asterisks
This means to match whatever CSV term plus a comma comes before the five asterisks in your string. We then replace this with what you want, along with the five stars in the original pattern.
Demo here:
Rextester

I'd use a regular expression with a lookahead, to find a string of digits that precedes ",*****", and replace it with the new value. The regular expression you're looking for would be \d+(?=,\*{5}) - that is, one or more digits, with a lookahead consisting of a comma and five asterisks. So you'd write
newString = oldString.replaceAll("\\d+(?=,\\*{5})", "replacement");
Here is an explanation of the regex pattern used in the replacement:
\\d+ match any numbers of digits, but only when
(?=,\\*{5}) we can lookahead and assert that what follows immediately
is a single comma followed by five asterisks
It is important to note that the lookahead (?=,\\*{5}) asserts but does not consume. Hence, we can ignore it with regards to the replacement.

I considered newstr be "6"
String str = "9,3,5,*****,1,2,3";
char newstr = '6';
str = str.replace(str.charAt(str.indexOf(",*") - 1), newstr);
Also if you are not sure about str length check for IndexOutOfBoundException
and handle it

You could split on , and then join with a , (after replacing 5 with the desired value - say X). Like,
String[] arr = "9,3,5,*****,1,2,3".split(",");
arr[2] = "X";
System.out.println(String.join(",", arr));
Which outputs
9,3,X,*****,1,2,3

you can use spit() for replacing a string
String str = "9,3,5,*****,1,2,3";
String[] myStrings = str.split(",");
String str1 = myStrings[2];

Splitting a string keeping some delimiters but removing another

Basically I would like to split a string into an array delimiting by spaces and operators, but keep the operators while removing the spaces
ex. 3 52 9+- 2 3 * /
will be [3][52][9][+][-][2][3][*][/]

The logic you want when splitting is to consume delimiters which are whitespace and to not consume delimiters which are arithmetic symbols. Towards this end, we can use a lookahead to split by symbol, and use plain \\s to split by whitespace and remove it from the result.
String input = "3 52 9+- 2 3 * /";
input = input.replaceAll("([\\+\\-*/])(.)", " $1$2")
.replaceAll("\\s+", " ");
String[] parts = input.split("(?<=[\+\-*/])|\\s")
System.out.println(Arrays.toString(parts));
Output:
[3, 52, 9, +, -, 2, 3, *, /]

import java.util.ArrayList;
import java.util.List;
public class Test {
public static void main(String[] args) {
String input = "3 52 9+- 2 3 * /";
input = input.replaceAll("([\\+\\-*/])", " $1 ").replaceAll("\\s+", " ");
String[] parts = input.split("(?<=[+\\-*/ ])");
List<String> finalList = new ArrayList<String>();
for(String part : parts) {
if(part.trim().length() > 0) {
finalList.add(part);
}
}
System.out.println(finalList);
}
}
Output
[3 , 52 , 9 , +, -, 2 , 3 , *, /]

Try this regex:
([\-]?[^\s\+\-\*\/]+|[\+\-\*\/])
It will select:
[\-]? signed or unsigned
[^\s\+\-\*\/] characters that is neither spaces nor [+ - * /]
or [\+\-\*\/] [+ - * /]
Just match your case.