fixed compiling issue

Author: Thidas Senavirathna

src/main/java/com/mycmd/commands/UptimeCommand.java

@@ -22,24 +22,33 @@
  */
 public class UptimeCommand implements Command {
     @Override
-    public void execute(String[] args, ShellContext context) {
-        long uptimeMillis = System.currentTimeMillis() - context.getStartTime();
+    public void execute(String[] args, ShellContext context) throws IOException {
+        Instant startTime = context.getStartTime();
+        Instant now = Instant.now();
 
-        long totalSeconds = uptimeMillis / 1000;
-        long hours = totalSeconds / 3600;
-        long minutes = (totalSeconds % 3600) / 60;
-        long seconds = totalSeconds % 60;
+        // Calculate duration between start time and now
+        Duration uptime = Duration.between(startTime, now);
 
-        System.out.printf("Up since %dh %dm %ds%n", hours, minutes, seconds);
+        long seconds = uptime.getSeconds();
+        long days = seconds / 86400;
+        long hours = (seconds % 86400) / 3600;
+        long minutes = (seconds % 3600) / 60;
+        long secs = seconds % 60;
+        
+        System.out.print("Uptime: ");
+        if (days > 0) {
+            System.out.print(days + " day" + (days != 1 ? "s" : "") + ", ");
+        }
+        System.out.printf("%02d:%02d:%02d%n", hours, minutes, secs);
     }
 
     @Override
     public String description() {
-        return "Display how long the shell has been running since startup.";
+        return "Display how long the shell has been running.";
     }
 
     @Override
     public String usage() {
         return "uptime";
     }
-}
+}