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Using Regular Expression in Java to extract information from a String

I have one input String like this:
"I am Duc/N Ta/N Van/N"
String "/N" present it is the Name of one person.
The expected output is:
Name: Duc Ta Van
How can I do it by using regular expression?

You can use Pattern and Matcher like this :
String input = "I am Duc/N Ta/N Van/N";
Pattern pattern = Pattern.compile("([^\\s]+)/N");
Matcher matcher = pattern.matcher(input);
String result = "";
while (matcher.find()) {
result+= matcher.group(1) + " ";
}
System.out.println("Name: " + result.trim());
Output
Name: Duc Ta Van
Another Solution using Java 9+
From Java9+ you can use Matcher::results like this :
String input = "I am Duc/N Ta/N Van/N";
String regex = "([^\\s]+)/N";
Pattern pattern = Pattern.compile(regex);
Matcher matcher = pattern.matcher(input);
String result = matcher.results().map(s -> s.group(1)).collect(Collectors.joining(" "));
System.out.println("Name: " + result); // Name: Duc Ta Van

Here is the regex to use to capture every "name" preceded by a /N
(\w+)\/N
Validate with Regex101
Now, you just need to loop on every match in that String and concatenate the to get the result :
String pattern = "(\\w+)\\/N";
String test = "I am Duc/N Ta/N Van/N";
Matcher m = Pattern.compile(pattern).matcher(test);
StringBuilder sbNames = new StringBuilder();
while(m.find()){
sbNames.append(m.group(1)).append(" ");
}
System.out.println(sbNames.toString());
Duc Ta Van
It is giving you the hardest part. I let you adapt this to match your need.
Note :
In java, it is not required to escape a forward slash, but to use the same regex in the entire answer, I will keep "(\\w+)\\/N", but "(\\w+)/N" will work as well.

I've used "[/N]+" as the regular expression.
Regex101
[] = Matches characters inside the set
\/ = Matches the character / literally (case sensitive)
+ = Matches between one and unlimited times, as many times as possible, giving back as needed (greedy)

String split single quotes

iam new in regural expressions. I have a String
String span = "some text, param1:'1123',some text, param2:'3444';"
Now i want to use split, and get values of param1 and param2.
So i think if i use split by single quotes, i will get array elements with length == 2.
My problem is my split by single quotes doesn't work.
I think i need to put inside single quotes some regex
String[] elements = span.split("''");
param1 = elements[elements.length-2];
param2 = elements[elements.length-1];
So my output will be:
1123
3444

You can do this using regular expression:
'(.*?)'
' is a special character in Java so you need to use Pattern.quote() to treat it as a literal.
Try:
String span = "some text, param1:'1123',some text, param2:'3444';";
Pattern p = Pattern.compile(Pattern.quote("'") + "(.*?)" + Pattern.quote("'"));
Matcher m = p.matcher(span);
while (m.find()) {
System.out.println(m.group(1));
}
This outputs:
1123
3444

My solution is :
Pattern pattern = Pattern.compile("'(?:[^']|'')+'");
ArrayList<String> values = new ArrayList<>();
Matcher matcher = pattern.matcher(span);
while (matcher.find()) {
values.add(matcher.group());
}
nom = values.get(1).replace("'","");

How to split a long string in Java?

How to edit this string and split it into two?
String asd = {RepositoryName: CodeCommitTest,RepositoryId: 425f5fc5-18d8-4ae5-b1a8-55eb9cf72bef};
I want to make two strings.
String reponame;
String RepoID;
reponame should be CodeCommitTest
repoID should be 425f5fc5-18d8-4ae5-b1a8-55eb9cf72bef
Can someone help me get it? Thanks

Here is Java code using a regular expression in case you can't use a JSON parsing library (which is what you probably should be using):
String pattern = "^\\{RepositoryName:\\s(.*?),RepositoryId:\\s(.*?)\\}$";
String asd = "{RepositoryName: CodeCommitTest,RepositoryId: 425f5fc5-18d8-4ae5-b1a8-55eb9cf72bef}";
String reponame = "";
String repoID = "";
Pattern r = Pattern.compile(pattern);
Matcher m = r.matcher(asd);
if (m.find()) {
reponame = m.group(1);
repoID = m.group(2);
System.out.println("Found reponame: " + reponame + " with repoID: " + repoID);
} else {
System.out.println("NO MATCH");
}
This code has been tested in IntelliJ and runs without error.
Output:
Found reponame: CodeCommitTest with repoID: 425f5fc5-18d8-4ae5-b1a8-55eb9cf72bef

Assuming there aren't quote marks in the input, and that the repository name and ID consist of letters, numbers, and dashes, then this should work to get the repository name:
Pattern repoNamePattern = Pattern.compile("RepositoryName: *([A-Za-z0-9\\-]+)");
Matcher matcher = repoNamePattern.matcher(asd);
if (matcher.find()) {
reponame = matcher.group(1);
}
and you can do something similar to get the ID. The above code just looks for RepositoryName:, possibly followed by spaces, followed by one or more letters, digits, or hyphen characters; then the group(1) method extracts the name, since it's the first (and only) group enclosed in () in the pattern.

Java Split String by colon on both side

Can you suggest me an approach by which I can split a String which is like:
:31C:150318
:31D:150425 IN BANGLADESH
:20:314015040086
So I tried to parse that string with
:[A-za-z]|\\d:
This kind of regular expression, but it is not working . Please suggest me a regular expression by which I can split that string with 20 , 31C , 31D etc as Keys and 150318 , 150425 IN BANGLADESH etc as Values .
If I use string.split(":") then it would not serve my purpose.
If a string is like:
:20: MY VALUES : ARE HERE
then It will split up into 3 string , and key 20 will be associated with "MY VALUES" , and "ARE HERE" will not associated with key 20 .

You may use matching mechanism instead of splitting since you need to match a specific colon in the string.
The regex to get 2 groups between the first and second colon and also capture everything after the second colon will look like
^:([^:]*):(.*)$
See demo. The ^ will assert the beginning of the string, ([^:]*) will match and capture into Group 1 zero or more characters other than :, and (.*) will match and capture into Group 2 the rest of the string. $ will assert the position at the end of a single line string (as . matches any symbol but a newline without Pattern.DOTALL modifier).
String s = ":20:AND:HERE";
Pattern pattern = Pattern.compile("^:([^:]*):(.*)$");
Matcher matcher = pattern.matcher(s);
while (matcher.find()){
System.out.println("Key: " + matcher.group(1) + ", Value: " + matcher.group(2) + "\n");
}
Result for this demo: Key: 20, Value: AND:HERE

You can use the following to split:
^[:]+([^:]+):

Try with split function of String class
String[] splited = string.split(":");
For your requirements:
String c = ":31D:150425 IN BANGLADESH:todasdsa";
c=c.substring(1);
System.out.println("C="+c);
String key= c.substring(0,c.indexOf(":"));
String value = c.substring(c.indexOf(":")+1);
System.out.println("key="+key+" value="+value);
Result:
C=31D:150425 IN BANGLADESH:todasdsa
key=31D value=150425 IN BANGLADESH:todasdsa

RegEx: Grabbing value between quotation marks from string

This is related to: RegEx: Grabbing values between quotation marks.
If there is a String like this:
HYPERLINK "hyperlink_funda.docx" \l "Sales"
The regex given on the link
(["'])(?:(?=(\\?))\2.)*?\1
is giving me
[" HYPERLINK ", " \l ", " "]
What regex will return values enclosed in quotation mark (specifically between the \" marks) ?
["hyperlink_funda.docx", "Sales"]
Using Java, String.split(String regex) way.

You're not supposed to use that with .split() method. Instead use a Pattern with capturing groups:
{
Pattern pattern = Pattern.compile("([\"'])((?:(?=(\\\\?))\\3.)*?)\\1");
Matcher matcher = pattern.matcher(" HYPERLINK \"hyperlink_funda.docx\" \\l \"Sales\" ");
while (matcher.find())
System.out.println(matcher.group(2));
}
Output:
hyperlink_funda.docx
Sales
Here is a regex demo, and here is an online code demo.

I think you are misunderstanding the nature of the String.split method. Its job is to find a way of splitting a string by matching the features of the separator, not by matching features of the strings you want returned.
Instead you should use a Pattern and a Matcher:
String txt = " HYPERLINK \"hyperlink_funda.docx\" \\l \"Sales\" ";
String re = "\"([^\"]*)\"";
Pattern p = Pattern.compile(re);
Matcher m = p.matcher(txt);
ArrayList<String> matches = new ArrayList<String>();
while (m.find()) {
String match = m.group(1);
matches.add(match);
}
System.out.println(matches);