Java Regex - How to replace a pattern starts with and ends with

Question

I have 2 Scenarios:

1. String Starts with Sample Country ! i.e. Sample Country ! Test Data

I want a regex to replace Sample Country ! with Empty String, Country here is not fixed, it can be US, France etc

I tried:

System.out.println(str.replaceAll("^(Sample[^!]+!)", ""));

I am getting the Output

! Test Data 

whereas I just want

Test Data

2. String ends with Sample Country ! i.e. Test Data Sample Country ! here also I just want

   Test Data

Can someone help to provide the correct Regular expression with the explanation. Thanks a lot

Answer 1

Try this regex here:

String[] testcases = new String[] {
    "Sample foo ! Test Data", 
    "Sample bar ! Test Data", 
    "Test Data Sample foo !", 
    "Test Data Sample bar !"
};

for (String str : testcases) {
    System.out.println(str.replaceAll("(.* ?)(Sample[a-zA-Z ]+ ! ?)(.*)", "$1$3"));
}

Explanation:

(.* ?) // first match group, matches anything, followed by an optional space

(Sample[a-zA-Z ]+ ! ?) // second match group, matches the String "Sample followed by a series of letters (your country), a whitespace, an exclamation mark and an optional space

(.*) // third match group, matches anything

So the second match group ($2) will contain your "Sample Country" string and we can just replace the result with only the first ($1) and the third ($3) match group.