如何使用String.split()按正则分割字符串并排除特定子串、去除空元素？

Got it, let's tackle this split problem you're facing. The issue with your current regex is that it treats - and > as separate delimiters, which breaks ORDER_ITEMS->TOTAL_QTY into two parts, plus it generates empty strings from consecutive delimiters (like parentheses and spaces next to each other).

Solution Code #

Here's how you can adjust your regex and filter out empty strings to get the exact result you want:

import java.util.Arrays;

public class SplitExample {
    public static void main(String[] args) {
        String expr = "round((TOTAL_QTY * 100) / SUM(ORDER_ITEMS->TOTAL_QTY) , 1)";
        // Regex to split on delimiters but preserve "->"
        String regex = "[\\s()*+\\/^!@#%&]|-(?!>)|(?<!-)>";
        
        String[] tokens = expr.split(regex);
        // Filter out empty strings from the result
        tokens = Arrays.stream(tokens).filter(s -> !s.isEmpty()).toArray(String[]::new);
        
        // Print the result to verify
        System.out.println(Arrays.toString(tokens));
        // Output: [round, TOTAL_QTY, 100, SUM, ORDER_ITEMS->TOTAL_QTY, 1]
    }
}

How the Regex Works #

Let's break down the regex [\\s()*+\\/^!@#%&]|-(?!>)|(?<!-)>:

• [\\s()*+\\/^!@#%&]: Matches whitespace, parentheses, and all your target operators (except - and > that form ->). These are standard delimiters we want to split on.
• -(?!>): Matches a - only if it's not followed by a > (so we don't split the -> in your identifier).
• (?<!-)>: Matches a > only if it's not preceded by a - (again, preserving the -> pair).

Why This Fixes Your Problem #

• Your original regex treated every - and > as a delimiter, which split ORDER_ITEMS->TOTAL_QTY into separate elements. This new regex skips splitting when - and > are paired together.
• The filter step removes any empty strings created by consecutive delimiters (like (( which would split into an empty string between the two parentheses).

内容的提问来源于stack exchange，提问作者a.toraby