add usage comments to checkVersion()

1 files changed, 12 insertions, 0 deletions

diff --git a/src/main/java/de/pixart/messenger/ui/UpdaterActivity.java b/src/main/java/de/pixart/messenger/ui/UpdaterActivity.java
index 548313c6c..b24958a43 100644
--- a/src/main/java/de/pixart/messenger/ui/UpdaterActivity.java
+++ b/src/main/java/de/pixart/messenger/ui/UpdaterActivity.java
@@ -162,6 +162,18 @@ public class UpdaterActivity extends Activity {
         alert.show();
     }
 
+    /**
+    * Use this instead of String.compareTo() for a non-lexicographical 
+    * comparison that works for version strings. e.g. "1.10".compareTo("1.6").
+    * 
+    * @note It does not work if "1.10" is supposed to be equal to "1.10.0".
+    * 
+    * @param str1 a string of ordinal numbers separated by decimal points. 
+    * @param str2 a string of ordinal numbers separated by decimal points.
+    * @return The result is a negative integer if str1 is _numerically_ less than str2. 
+    *         The result is a positive integer if str1 is _numerically_ greater than str2. 
+    *         The result is zero if the strings are _numerically_ equal.
+    */
     private int checkVersion(String remoteVersion, String installedVersion) {
         String[] remote = null;
         String[] installed = null;