How can I trim beginning and ending double quotes from a string?

You can use String#replaceAll() with a pattern of ^\"|\"$ for this.

E.g.

string = string.replaceAll("^\"|\"$", "");

To learn more about regular expressions, have al ook at http://regular-expression.info.

That said, this smells a bit like that you're trying to invent a CSV parser. If so, I'd suggest to look around for existing libraries, such as OpenCSV.

To remove the first character and last character from the string, use:

myString = myString.substring(1, myString.length()-1);

Also with Apache StringUtils.strip():

 StringUtils.strip(null, *)          = null
 StringUtils.strip("", *)            = ""
 StringUtils.strip("abc", null)      = "abc"
 StringUtils.strip("  abc", null)    = "abc"
 StringUtils.strip("abc  ", null)    = "abc"
 StringUtils.strip(" abc ", null)    = "abc"
 StringUtils.strip("  abcyx", "xyz") = "  abc"

So,

final String SchrodingersQuotedString = "may or may not be quoted";
StringUtils.strip(SchrodingersQuotedString, "\""); //quoted no more

This method works both with quoted and unquoted strings as shown in my example. The only downside is, it will not look for strictly matched quotes, only leading and trailing quote characters (ie. no distinction between "partially and "fully" quoted strings).