“我有最短的”挑战，以下是我的;)

迭代:

public static String join(String s, Object... a) {
    StringBuilder o = new StringBuilder();
    for (Iterator<Object> i = Arrays.asList(a).iterator(); i.hasNext();)
        o.append(i.next()).append(i.hasNext() ? s : "");
    return o.toString();
}

递归:

public static String join(String s, Object... a) {
    return a.length == 0 ? "" : a[0] + (a.length == 1 ? "" : s + join(s, Arrays.copyOfRange(a, 1, a.length)));
}

不是在核心，不是。搜索“java array join string glue”会给你一些关于如何实现这一点的代码片段。

e.g.

public static String join(Collection s, String delimiter) {
    StringBuffer buffer = new StringBuffer();
    Iterator iter = s.iterator();
    while (iter.hasNext()) {
        buffer.append(iter.next());
        if (iter.hasNext()) {
            buffer.append(delimiter);
        }
    }
    return buffer.toString();
}

要从 “str1”、“str2”， “” 获取 “str1， str2”：

Stream.of("str1", "str2", "").filter(str -> !str.isEmpty()).collect(Collectors.joining(", ")); 

此外，您还可以添加额外的空检查

考虑到:

String[] a = new String[] { "Hello", "World", "!" };

然后，作为coobird的答案的替代方案，胶水是“，”:

Arrays.asList(a).toString().replaceAll("^\\[|\\]$", "")

或者连接不同的字符串，例如“&"．

Arrays.asList(a).toString().replaceAll(", ", " & ").replaceAll("^\\[|\\]$", "")

然而……只有当你知道数组或列表中的值不包含字符串“，”时，这个方法才有效。

我的自旋。

public static String join(Object[] objects, String delimiter) {
  if (objects.length == 0) {
    return "";
  }
  int capacityGuess = (objects.length * objects[0].toString().length())
      + ((objects.length - 1) * delimiter.length());
  StringBuilder ret = new StringBuilder(capacityGuess);
  ret.append(objects[0]);
  for (int i = 1; i < objects.length; i++) {
    ret.append(delimiter);
    ret.append(objects[i]);
  }
  return ret.toString();
}

public static String join(Object... objects) {
  return join(objects, "");
}

类似的替代方案

/**
 * @param delimiter 
 * @param inStr
 * @return String
 */
public static String join(String delimiter, String... inStr)
{
    StringBuilder sb = new StringBuilder();
    if (inStr.length > 0)
    {
        sb.append(inStr[0]);
        for (int i = 1; i < inStr.length; i++)
        {
            sb.append(delimiter);                   
            sb.append(inStr[i]);
        }
    }
    return sb.toString();
}