I am new to regex and help me with a solution
for example i have a string as below,
String str = "this is a hello world string and duplicate starts from here this is a hello world string";
i wanted to check the following condition using regex.
if("this is a hello world string" has appeared more than once in String str){
return false;
}
else{
return true;
}
How this can be achieved?
You may also use regex like in this example:
String str1 = "this is a hello world string";
String str2 = "this is a hello world string and duplicate starts from here this is a hello world string";
Pattern pattern = Pattern.compile(str1);
Matcher matcher = pattern.matcher(str2);
int count = 0;
while(matcher.find()){
count++;
}
if(count > 0) {
return true;
} else {
return false;
}
Hope it helps. Cheers.
"this is a hello world string". But what i wanted is different
You can do it without a regex like this
if(str.indexOf("this is a hello world string") != str.lastIndexOf("this is a hello world string")) {
return false;
}
else{
return true;
}
You can use below code
String duplicatePattern = "(?i)\\b(\\w+)\\b[\\w\\W]*\\b\\1\\b";
Pattern p = Pattern.compile(duplicatePattern);
String phrase = "this is a hello world string and duplicate starts from here this is a hello world string";
Matcher m = p.matcher(phrase);
String val = null;
while (m.find()) {
val = m.group();
System.out.println("Matching segment is \"" + val + "\"");
System.out.println("Duplicate word: " + m.group(1)+ "\n");
}
Matching segment is "this is a hello world string and duplicate starts from here this" Duplicate word: this but it doesn check for the duplicate stringIf you literally want to find two duplicate "things" without specifying what those things are, you're going to have a hard time writing up the regex for it.
This matches two "duplicate things":
(.+)(?=.+)\1
Note, it finds "anything" and asserts that "anything else" can be in between it and another instance of itself.
Yeah, like that isn't confusing.
