Using regular expressions to rename a string

Question

In java, I want to rename a String so it always ends with ".mp4"

Suppose we have an encoded link, looking as follows:

String link = www.somehost.com/linkthatIneed.mp4?e=13974etc...

So, how do I rename the link String so it always ends with ".mp4"?

link = www.somehost.com/linkthatIneed.mp4  <--- that's what I need the final String to be.

Answer 1

Just get the string until the .mp4 part using the following regex :

^(.*\\.mp4)

and the first captured group is what you want.

Demo: http://regex101.com/r/zQ6tO5

Answer 2

Another way to do this would be to split the string with ".mp4" as a split char and then add it again :)

Something like :

String splitChar = ".mp4";
String link = "www.somehost.com/linkthatIneed.mp4?e=13974etcrezkhjk"
String finalStr = link.split(splitChar)[0] + splitChar;

easy to do ^^

PS: I prefer to pass by regex but it ask for more knowledge about regex ^^

Answer 3

Well you can also do this:

Match the string with the below regex

\?.*

and replace it with empty string.

Demo: http://regex101.com/r/iV1cZ8

Answer 4

Try below code,

  private String trimStringAfterOccurance(String link, String occuranceString) {

    Integer  occuranceIndex =  link.indexOf(occuranceString);

    String trimmedString = (String) link.subSequence(0, occuranceIndex + occuranceString.length() );    

    System.out.println(trimmedString);

    return trimmedString;
}