Java String类API收纳（持续更新）

1、join

源码：

     /**
     * @see java.util.StringJoiner
     * @since 1.8
     */
    public static String join(CharSequence delimiter, CharSequence... elements) {
        Objects.requireNonNull(delimiter);
        Objects.requireNonNull(elements);
        // Number of elements not likely worth Arrays.stream overhead.
        StringJoiner joiner = new StringJoiner(delimiter);
        for (CharSequence cs: elements) {
            joiner.add(cs);
        }
        return joiner.toString();
    }

注：
*Java 8之后才有
*delimiter：分隔符

实例：

        String message = String.join("-","java","is","great");
        System.out.println(message);

结果：
java-is-great

2、StringJoiner

源码：

    public StringJoiner(CharSequence delimiter,
                        CharSequence prefix,
                        CharSequence suffix) {
        Objects.requireNonNull(prefix, "The prefix must not be null");
        Objects.requireNonNull(delimiter, "The delimiter must not be null");
        Objects.requireNonNull(suffix, "The suffix must not be null");
        // make defensive copies of arguments
        this.prefix = prefix.toString();
        this.delimiter = delimiter.toString();
        this.suffix = suffix.toString();
        this.emptyValue = this.prefix + this.suffix;
    }

注：
delimiter：分隔符
prefix：前缀
suffix：后缀

实例：

        StringJoiner stringJoiner = new StringJoiner(":","[","]");
        String string = stringJoiner.add("Python").add("java").add("scala").toString();
        System.out.println(string);

输出：
[Python:java:scala]