Merge pull request #156 from simon-liubin/update/stringutil

 join([],sep,pre)

Author: longbai

src/main/java/com/qiniu/util/StringUtils.java

@@ -13,108 +13,25 @@ private StringUtils() {
     }
 
     /**
-     * 以指定的分隔符来进行字符串元素连接
-     * <p>
-     * 例如有字符串数组array和连接符为逗号(,)
-     * <code>
-     * String[] array = new String[] { "hello", "world", "qiniu", "cloud","storage" };
-     * </code>
-     * 那么得到的结果是:
-     * <code>
-     * hello,world,qiniu,cloud,storage
-     * </code>
-     * </p>
-     *
-     * @param array 需要连接的字符串数组
-     * @param sep   元素连接之间的分隔符
-     * @return 连接好的新字符串
+     * @see #join(Object[] array, String sep, String prefix)
      */
-    public static String join(String[] array, String sep) {
+    public static String join(Object[] array, String sep) {
         return join(array, sep, null);
     }
 
     /**
-     * 以指定的分隔符来进行字符串元素连接
-     * <p>
-     * 例如有字符串数组array和连接符为逗号(,)
-     * <code>
-     * String[] array = new String[] { "hello", "world", "qiniu", "cloud","storage" };
-     * </code>
-     * 那么得到的结果是:
-     * <code>
-     * hello,world,qiniu,cloud,storage
-     * </code>
-     * </p>
-     *
-     * @param array  需要连接的字符串数组
-     * @param sep    元素连接之间的分隔符
-     * @param prefix 前缀字符串
-     * @return 连接好的新字符串
+     * @see #join(Object[] array, String sep, String prefix)
      */
-    public static String join(String[] array, String sep, String prefix) {
-        if (array == null) {
-            return null;
-        }
-
-        int arraySize = array.length;
-        int sepSize = 0;
-        if (sep != null && !sep.equals("")) {
-            sepSize = sep.length();
-        }
-
-        int bufSize = (arraySize == 0 ? 0 : ((array[0] == null ? 16 : array[0].length()) + sepSize) * arraySize);
-        StringBuilder buf = new StringBuilder(bufSize);
-        if (prefix != null) {
-            buf.append(prefix);
-        }
-        for (int i = 0; i < arraySize; i++) {
-            if (i > 0) {
-                buf.append(sep);
-            }
-            if (array[i] != null) {
-                buf.append(array[i]);
-            }
-        }
-        return buf.toString();
+    public static String join(Collection list, String sep) {
+        return join(list, sep, null);
     }
 
     /**
-     * 以指定的分隔符来进行字符串列表连接
-     *
-     * @param list   需要连接的字符串列表
-     * @param sep    元素连接之间的分隔符
-     * @param prefix 前缀字符串
-     * @return 连接好的新字符串
+     * @see #join(Object[] array, String sep, String prefix)
      */
-    public static String join(Collection<String> list, String sep, String prefix) {
-        if (list == null) {
-            return null;
-        }
-        int arraySize = list.size();
-        if (arraySize == 0) {
-            return prefix;
-        }
-        int sepSize = 0;
-        if (sep != null && !sep.equals("")) {
-            sepSize = sep.length();
-        }
-        String first = list.iterator().next();
-        int bufSize = ((first == null ? 16 : first.length()) + sepSize) * arraySize;
-        StringBuilder buf = new StringBuilder(bufSize);
-        if (prefix != null) {
-            buf.append(prefix);
-        }
-        int count = 0;
-        for (String it : list) {
-            count++;
-            if (it != null) {
-                buf.append(it);
-                if (count < arraySize) {
-                    buf.append(sep);
-                }
-            }
-        }
-        return buf.toString();
+    public static String join(Collection list, String sep, String prefix) {
+        Object[] array = list == null ? null : list.toArray();
+        return join(array, sep, prefix);
     }
 
     /**
@@ -137,31 +54,29 @@ public static String join(Collection<String> list, String sep, String prefix) {
      */
     public static String join(Object[] array, String sep, String prefix) {
         if (array == null) {
-            return null;
+            return "";
         }
 
         int arraySize = array.length;
 
         if (arraySize == 0) {
-            return prefix;
+            return "";
         }
-        int sepSize = 0;
-        if (sep != null && !sep.equals("")) {
-            sepSize = sep.length();
+
+        if (sep == null) {
+            sep = "";
         }
 
-        int bufSize = ((array[0] == null ? 16 : array[0].toString().length()) + sepSize) * arraySize;
-        StringBuilder buf = new StringBuilder(bufSize);
-        if (prefix != null) {
-            buf.append(prefix);
+        if (prefix == null) {
+            prefix = "";
         }
+
+        StringBuilder buf = new StringBuilder(prefix);
         for (int i = 0; i < arraySize; i++) {
             if (i > 0) {
                 buf.append(sep);
             }
-            if (array[i] != null) {
-                buf.append(array[i]);
-            }
+            buf.append(array[i] == null ? "" : array[i]);
         }
         return buf.toString();
     }