formatBytesForDisplay() - don't include decimal part for e.g. 3 B (was saying 3.0 B), add tests

Author: nlevitt

src/main/java/org/archive/util/ArchiveUtils.java

@@ -597,23 +597,29 @@ public static String doubleToString(double val, int maxFractionDigits, int minFr
      */
     public static String formatBytesForDisplay(long amount) {
         double displayAmount = (double) amount;
-        int unitPowerOf1024 = 0; 
+        int unitPowerOf1024 = 0;
 
         if(amount <= 0){
             return "0 B";
         }
-        
-        while(displayAmount>=1024 && unitPowerOf1024 < 4) {
+
+        final String[] units = { " B", " KiB", " MiB", " GiB", " TiB" };
+
+        while (displayAmount >= 1024 && unitPowerOf1024 < units.length - 1) {
             displayAmount = displayAmount / 1024;
             unitPowerOf1024++;
         }
-        
-        final String[] units = { " B", " KiB", " MiB", " GiB", " TiB" };
-        
-        // ensure at least 2 significant digits (#.#) for small displayValues
-        int fractionDigits = (displayAmount < 10) ? 1 : 0; 
+
+        int fractionDigits;
+        if (unitPowerOf1024 == 0 || displayAmount >= 10) {
+            fractionDigits = 0;
+        } else { 
+            // ensure at least 2 significant digits (#.#) for small displayValues
+            fractionDigits = 1;
+        }
+
         return doubleToString(displayAmount, fractionDigits, fractionDigits) 
-                   + units[unitPowerOf1024];
+                + units[unitPowerOf1024];
     }
 
     /**

src/test/java/org/archive/util/ArchiveUtilsTest.java

@@ -247,6 +247,9 @@ public void testFormatBytesForDisplayPrecise(){
                 .formatBytesForDisplay(-1)); 
         assertEquals("0 bytes", "0 B", ArchiveUtils
                 .formatBytesForDisplay(0));
+        assertEquals("1 B", ArchiveUtils.formatBytesForDisplay(1));
+        assertEquals("9 B", ArchiveUtils.formatBytesForDisplay(9));
+        assertEquals("512 B", ArchiveUtils.formatBytesForDisplay(512));
         assertEquals("1023 bytes", "1,023 B", ArchiveUtils
                 .formatBytesForDisplay(1023));
         assertEquals("1025 bytes", "1.0 KiB", ArchiveUtils