Possible NumberFormatException thrown from JSONTokener

[arthurscchan]

Description of the bug.

In the JSONTokener::nextString() method, there are two lines of code (Line 258 and 261) that try to interpret Unicode characters which are represented with a 2-digit or 4-digit integer. The code missed the test rather the value of \u or \x is a valid integer to parse. If an invalid string is being passed in, the code will throw an unexpected NumberFormatException.

Proof of Concept code that triggers the bug.

import org.codehaus.jettison.json.JSONArray;
import org.codehaus.jettison.json.JSONTokener;

public class ProofOfConcept {
  public static void main(String...args) throws Exception {
    new JSONArray(new JSONTokener("[\"\\xgg\"]"));
  }
}

Just compile and run the proof of concept code could trigger the bug.

Suggested fix.
Add a checking of the possible values before parsing them to the Integer::parseInt(String)`` method, or catch the possible NumberFormatException and throw a unified JSONException by the syntaxError(String) method to avoid confusion to the user.