如何从Java中的特定索引获取关键字

Question

Suppose I have a string:

String advise = "eat healthy food";

In the string I only know the keyword “healthy”. I don't know what has before the word nor what has after the word. I just only know the middle word. So how can I get the before (“eat”) and after (“food”) keyword of “healthy”?

Note: Here the middle word's size is always specfic but the other two word's size is always different. Here “eat” and “food” have been used as an example only. These two words may be anything anytime.

I need to get these two words into two different strings, not in the same string.

Answer 1

Just split the string:

advise.split("healthy");

The first value in the array will be "eat", the second will be "food".

Answer 2

Here is a more general purpose solution that will handle more complex strings.

public static void main (String[] args)
{
    String keyword = "healthy";

    String advise = "I want to eat healthy food today";

    Pattern p = Pattern.compile("([\\s]?+[\\w]+[\\s]+)" + keyword + "([\\s]+[\\w]+[\\s]?+)");
    Matcher m = p.matcher(advise);

    if (m.find())
    {
        String before = m.group(1).trim();
        String after = m.group(2).trim();

        System.out.println(before);
        System.out.println(after);
    }
    else
    {
        System.out.println("The keyword was not found.");
    }
}

Outputs:

eat

food

Answer 3

I think you can use split and get all the words separately as you wanted.

String advise = "eat healthy food";
String[] words = advise.split("healthy");
List<String> word = Arrays.asList(words);
word.forEach(w-> System.out.println(w.trim()));