How to remove the URLs present in text example
String str=\"Fear psychosis after #AssamRiots - http://www.google.com/LdEbWTgD http://www.yahoo.com/mksVZKBz\"
Well, you haven't provided any info about your text, so with the assumption of your text looking like this: "Some text here http://www.example.com some text there", you can do this:
String yourText = "blah-blah";
String cleartext = yourText.replaceAll("http.*?\\s", " ");
This will remove all sequences starting with "http" and up to the first space character.
You should read the Javadoc on String class. It will make things clear for you.