From b75c77d2699b971e7b44a46d52b5696fee3efd31 Mon Sep 17 00:00:00 2001
From: BobHanson <hansonr@stolaf.edu>
Date: Thu, 28 May 2020 15:56:38 -0500
Subject: [PATCH] JAL-3636 ColorUtils cleaner test for hex color

---
 src/jalview/util/ColorUtils.java  |   17 ++++++++++++-----
 src/jalview/util/StringUtils.java |   25 +++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/src/jalview/util/ColorUtils.java b/src/jalview/util/ColorUtils.java
index 60129fb..c1feeee 100644
--- a/src/jalview/util/ColorUtils.java
+++ b/src/jalview/util/ColorUtils.java
@@ -219,12 +219,15 @@ public class ColorUtils
     colour = colour.trim();
 
     Color col = null;
-    try
-    {
-      int value = Integer.parseInt(colour, 16);
-      col = new Color(value);
-    } catch (NumberFormatException ex)
+    if (colour.length() == 6 && StringUtils.isHexString(colour))
     {
+      try
+      {
+        int value = Integer.parseInt(colour, 16);
+        col = new Color(value);
+      } catch (NumberFormatException ex)
+      {
+      }
     }
 
     if (col == null)
@@ -252,6 +255,10 @@ public class ColorUtils
 
     return col;
   }
+  
+  public static boolean couldBeHexColor(String n) {
+    return (n.length() > 0 && "abcdefABCDEF".indexOf(n.charAt(0)) >= 0);
+  }
 
   /**
    * Constructs a colour from a text string. The hashcode of the whole string is
diff --git a/src/jalview/util/StringUtils.java b/src/jalview/util/StringUtils.java
index 1f114a8..c6af7f0 100644
--- a/src/jalview/util/StringUtils.java
+++ b/src/jalview/util/StringUtils.java
@@ -568,4 +568,29 @@ public class StringUtils
     }
     return enc;
   }
+
+  /**
+   * Answers true if the string is not empty and consists only of digits, or
+   * characters 'a'-'f' or 'A'-'F', else false
+   * 
+   * @param s
+   * @return
+   */
+  public static boolean isHexString(String s)
+  {
+    int j = s.length();
+    if (j == 0)
+    {
+      return false;
+    }
+    for (int i = 0; i < j; i++)
+    {
+      int c = s.charAt(i);
+      if (!(c >= '0' && c <= '9' || c >= 'a' && c <= 'f' || c >= 'A' && c <= 'F'))
+      {
+        return false;
+      }
+    }
+    return true;
+  }
 }
-- 
1.7.10.2