JavaScript有Array.join()

js>["Bill","Bob","Steve"].join(" and ")
Bill and Bob and Steve

Java有这样的东西吗?我知道我可以用StringBuilder自己拼凑一些东西:

static public String join(List<String> list, String conjunction)
{
   StringBuilder sb = new StringBuilder();
   boolean first = true;
   for (String item : list)
   {
      if (first)
         first = false;
      else
         sb.append(conjunction);
      sb.append(item);
   }
   return sb.toString();
}

. .但是如果像这样的东西已经是JDK的一部分,那么这样做就没有意义了。


当前回答

试试这个:

java.util.Arrays.toString(anArray).replaceAll(", ", ",")
                .replaceFirst("^\\[","").replaceFirst("\\]$","");

其他回答

我写了这个(我用它来bean和利用toString,所以不要写Collection<String>):

public static String join(Collection<?> col, String delim) {
    StringBuilder sb = new StringBuilder();
    Iterator<?> iter = col.iterator();
    if (iter.hasNext())
        sb.append(iter.next().toString());
    while (iter.hasNext()) {
        sb.append(delim);
        sb.append(iter.next().toString());
    }
    return sb.toString();
}

但是JSP不支持Collection,所以对于TLD我写了:

public static String join(List<?> list, String delim) {
    int len = list.size();
    if (len == 0)
        return "";
    StringBuilder sb = new StringBuilder(list.get(0).toString());
    for (int i = 1; i < len; i++) {
        sb.append(delim);
        sb.append(list.get(i).toString());
    }
    return sb.toString();
}

并放入。tld文件:

<?xml version="1.0" encoding="UTF-8"?>
<taglib version="2.1" xmlns="http://java.sun.com/xml/ns/javaee"
    <function>
        <name>join</name>
        <function-class>com.core.util.ReportUtil</function-class>
        <function-signature>java.lang.String join(java.util.List, java.lang.String)</function-signature>
    </function>
</taglib>

并在JSP文件中使用它:

<%@taglib prefix="funnyFmt" uri="tag:com.core.util,2013:funnyFmt"%>
${funnyFmt:join(books, ", ")}

在Android上你可以使用TextUtils类。

TextUtils.join(" and ", names);

Java 8确实带来了

Collectors.joining(CharSequence delimiter, CharSequence prefix, CharSequence suffix)

方法,通过对空值使用前缀+后缀,该方法为nullsafe。

它可以以以下方式使用:

String s = stringList.stream().collect(Collectors.joining(" and ", "prefix_", "_suffix"))

收藏家。join (CharSequence delimiter)方法只是在内部调用joining(delimiter, "", "")。

Java 8中有三种可能性:

List<String> list = Arrays.asList("Alice", "Bob", "Charlie")

String result = String.join(" and ", list);

result = list.stream().collect(Collectors.joining(" and "));

result = list.stream().reduce((t, u) -> t + " and " + u).orElse("");

你可以这样做:

String aToString = java.util.Arrays.toString(anArray);
// Do not need to do this if you are OK with '[' and ']'
aToString = aToString.substring(1, aToString.length() - 1);

或者单行语句(仅当不需要'['和']'时)

String aToString = java.util.Arrays.toString(anArray).substring(1).replaceAll("\\]$", "");

希望这能有所帮助。