From 7d8353401ad0943a00423cb4f3e7d71a4b6a162f Mon Sep 17 00:00:00 2001
From: Miguel <miguel.tsuboyama@gmail.com>
Date: Thu, 10 Aug 2017 19:05:57 -0400
Subject: [PATCH] Adding JSONTokener.back() just before throwing JSONException

This forces JSONTokener.syntaxError(..) to point to the last character of the duplicate key.
---
 JSONObject.java | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/JSONObject.java b/JSONObject.java
index 9d5fc87..28f401e 100644
--- a/JSONObject.java
+++ b/JSONObject.java
@@ -232,12 +232,13 @@ public class JSONObject {
                 throw x.syntaxError("Expected a ':' after a key");
             }
             
-            // Replace: this.putOnce(key, x.nextValue());
             // Use syntaxError(..) to include error location
             
             if (key != null) {
                 // Check if key exists
             	if (this.opt(key) != null) {
+            		// back one token to point to the last key character
+            		x.back();
                     throw x.syntaxError("Duplicate key \"" + key + "\"");
             	}
                 // Only add value if non-null