如何从字符串数组或arraylist创建一个字符串？

Question

我如何提取字符串[]或arraylist中的所有元素,并将所有单词与它们之间的适当格式(具有单个空格)组合并存储在数组中.

String[] a = {"Java", "is", "cool"};

输出:Java很酷.

Answer 1

用一个StringBuilder.

String[] strings = {"Java", "is", "cool"};
StringBuilder builder = new StringBuilder();

for (String string : strings) {
    if (builder.length() > 0) {
        builder.append(" ");
    }
    builder.append(string);
}

String string = builder.toString();
System.out.println(string); // Java is cool

或者使用Apache Commons Lang StringUtils#join().

String[] strings = {"Java", "is", "cool"};
String string = StringUtils.join(strings, ' ');
System.out.println(string); // Java is cool

或者使用Java8 Arrays#stream().

String[] strings = {"Java", "is", "cool"};
String string = Arrays.stream(strings).collect(Collectors.joining(" "));
System.out.println(string); // Java is cool

Answer 2

我的建议是使用org.apache.commons.lang.StringUtils:

org.apache.commons.lang.StringUtils.join(a, " ");