JAL-1270 JAL-2885 clear properties before load

diff --git a/src/jalview/bin/Cache.java b/src/jalview/bin/Cache.java
index dc50843..dcd6546 100755 (executable)
--- a/src/jalview/bin/Cache.java
+++ b/src/jalview/bin/Cache.java
@@ -281,7 +281,7 @@ public class Cache
     @Override
     public synchronized Enumeration<Object> keys()
     {
-      return Collections.enumeration(new TreeSet<Object>(super.keySet()));
+      return Collections.enumeration(new TreeSet<>(super.keySet()));
     }
   };
 
@@ -334,7 +334,10 @@ public class Cache
     }
   }
 
-  /** Called when Jalview is started */
+  /**
+   * Loads properties from the given properties file. Any existing properties
+   * are first cleared.
+   */
   public static void loadProperties(String propsFile)
   {
     propertiesFile = propsFile;
@@ -369,6 +372,7 @@ public class Cache
       {
         fis = new FileInputStream(propertiesFile);
       }
+      applicationProperties.clear();
       applicationProperties.load(fis);
 
       // remove any old build properties
@@ -621,14 +625,14 @@ public class Cache
    * @param obj
    *          String value of property
    * 
-   * @return String value of property
+   * @return previous value of property (or null)
    */
-  public static String setProperty(String key, String obj)
+  public static Object setProperty(String key, String obj)
   {
-
+    Object oldValue = null;
     try
     {
-      applicationProperties.setProperty(key, obj);
+      oldValue = applicationProperties.setProperty(key, obj);
       if (!propsAreReadOnly)
       {
         FileOutputStream out = new FileOutputStream(propertiesFile);
@@ -640,7 +644,7 @@ public class Cache
       System.out.println(
               "Error setting property: " + key + " " + obj + "\n" + ex);
     }
-    return obj;
+    return oldValue;
   }
 
   /**