如何从字符串数组或arraylist创建一个字符串？

Question

how can i extract all the elements in a string [] or arraylist and combine all the words with proper formating(with a single space) between them and store in a array..

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

Output: Java is cool.

Answer 1

Use a 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

Or use Apache Commons Lang StringUtils#join() .

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

Or use Java8's 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, " ");