需要一个正则表达式和示例Java代码来从字符串中提取比较运算符[保留]

Question

I found a string - "Process Execution Time"==">300ms"

Previously i was using a regex to get the operator from other string. but when the operator is present in value section my existing regex does not work

My Existing regex - (. )(==|!=|>=|<=|>|<)(. )

Example :

"A">"B" Group 1 = A Group 2 = > Group 3 = B

"A"=="B" Group 1 = "A" Group 2 = == Group 3 = "B"

it breaks when > is in value section. please note i have all the value with in "".

"Process Execution Time"==">300ms"

Group 1 = "Process Execution Time"==" Group 2 = > Group 3 = 300ms

Whether my expectation is -

Group 1 = "Process Execution Time" Group 2 = == Group 3 = ">300ms"

I have tried ungreedy and it worked in www.regex101.com with regex (. )(==|!=|>=|<=|>|<)(. +)

But not able get any sample in java fro ungreedy regex matching ...

Thanks in advance for any help ..

Regards - Tutai

Answer 1

Since you've stated:

please note i have all the value with in "".

This would make it slightly easier, by just checking those in the regex:

"([^"]+)"(==|!=|>=|<=|>|<)"([^"]+)"

The [^"]+ means 1 or more non- " characters .

Here a test program for your three test cases:

import java.util.regex.*;
class Main{
  public static void main(String[] a){
    for(String testCase : new String[]{ "\"Process Execution Time\"==\">300ms\"",
                                         "\"A\">\"B\"",
                                         "\"A\"==\"B\"" }){
      System.out.println("Input: "+testCase);
      Matcher matcher = Pattern.compile("\"([^\"]+)\"(==|!=|>=|<=|>|<)\"([^\"]+)\"")
                               .matcher(testCase);
      if(matcher.find()){
        System.out.println("Group 1: "+matcher.group(1));
        System.out.println("Group 2: "+matcher.group(2));
        System.out.println("Group 3: "+matcher.group(3));
      }
      System.out.println();
    }
  }
}

Which will output:

Input: "Process Execution Time"==">300ms"
Group 1: Process Execution Time
Group 2: ==
Group 3: >300ms

Input: "A">"B"
Group 1: A
Group 2: >
Group 3: B

Input: "A"=="B"
Group 1: A
Group 2: ==
Group 3: B

Try it online.