Got rid of duplicated code to format durations

Added new functions and test cases.

airsonic-main/src/main/java/org/airsonic/player/domain/MediaFile.java

@@ -22,6 +22,7 @@ package org.airsonic.player.domain;
 import com.google.common.base.Function;
 import com.google.common.collect.Lists;
 import org.airsonic.player.util.FileUtil;
+import org.airsonic.player.util.StringUtil;
 import org.apache.commons.io.FilenameUtils;
 
 import java.io.File;
@@ -279,31 +280,8 @@ public class MediaFile {
         if (durationSeconds == null) {
             return null;
         }
-
-        StringBuilder result = new StringBuilder(8);
-
-        int seconds = durationSeconds;
-
-        int hours = seconds / 3600;
-        seconds -= hours * 3600;
-
-        int minutes = seconds / 60;
-        seconds -= minutes * 60;
-
-        if (hours > 0) {
-            result.append(hours).append(':');
-            if (minutes < 10) {
-                result.append('0');
-            }
-        }
-
-        result.append(minutes).append(':');
-        if (seconds < 10) {
-            result.append('0');
-        }
-        result.append(seconds);
-
-        return result.toString();
+        // Return in M:SS or H:MM:SS
+        return StringUtil.formatDuration(durationSeconds);
     }
 
     public Long getFileSize() {

airsonic-main/src/main/java/org/airsonic/player/service/upnp/CustomContentDirectory.java

@@ -89,27 +89,7 @@ public abstract class CustomContentDirectory extends AbstractContentDirectorySer
         if (seconds == null) {
             return null;
         }
-
-        StringBuilder result = new StringBuilder(8);
-
-        int hours = seconds / 3600;
-        seconds -= hours * 3600;
-
-        int minutes = seconds / 60;
-        seconds -= minutes * 60;
-
-        result.append(hours).append(':');
-        if (minutes < 10) {
-            result.append('0');
-        }
-        result.append(minutes).append(':');
-        if (seconds < 10) {
-            result.append('0');
-        }
-        result.append(seconds);
-        result.append(".0");
-
-        return result.toString();
+        return StringUtil.formatDurationHMMSS((int)seconds) + ".0";
     }
 
     protected String getBaseUrl() {

airsonic-main/src/main/java/org/airsonic/player/util/StringUtil.java

@@ -226,19 +226,33 @@ public final class StringUtil {
     }
 
     /**
-     * Formats a duration with minutes and seconds, e.g., "93:45"
+     * Formats a duration with minutes and seconds, e.g., "4:34" or "93:45"
      */
     public static String formatDurationMSS(int seconds) {
-        int minutes = seconds / 60;
-        int secs = seconds % 60;
-
-        StringBuilder builder = new StringBuilder(6);
-        builder.append(minutes).append(":");
-        if (secs < 10) {
-            builder.append("0");
+        if (seconds < 0) {
+            throw new IllegalArgumentException("seconds must be >= 0");
         }
-        builder.append(secs);
-        return builder.toString();
+        return String.format("%d:%02d", seconds / 60, seconds % 60);
+    }
+
+    /**
+     * Formats a duration with H:MM:SS, e.g., "1:33:45"
+     */
+    public static String formatDurationHMMSS(int seconds) {
+        int hours = seconds / 3600;
+        seconds -= hours * 3600;
+
+        return String.format("%d:%s%s", hours, seconds < 600 ? "0" : "", formatDurationMSS(seconds));
+    }
+
+    /**
+     * Formats a duration to M:SS or H:MM:SS
+     */
+    public static String formatDuration(int seconds) {
+        if (seconds >= 3600) {
+            return formatDurationHMMSS(seconds);
+        }
+        return formatDurationMSS(seconds);
     }
 
     /**