如何检查只包含一个单词的字符串。 如果一个字符串有一个句子，它应该返回false

Question

I know it's a wierd to ask a question like this. But i've got no options. The problem is

I've come across a requirement where i happens to add a condition where, If there is an input as a string, I should be able to allow all the strings which only contains one word. So if there are many words I should reject. How to add such check when I don't have specificity on such string.

Answer 1

If the words are separated by some kind of white space, you could use a simple regular expression for this:

Pattern wordPattern = Pattern.compile("\\w+");
Matcher wordMatcher = wordPattern.matcher(inputString);
if (!wordMatcher.matches()) {
    // discard user input
}

This will match all word characters ( [a-zA-Z_0-9] ). If your definition of "word" is different, the regex will need to be adapted.

Answer 2

So many ways you can achieve it, One of the simplest is..

String str = "abc def";
String [] array = str.trim().split(" ");
if(array.lenght==1){
// allow if lenght = 1, or a word....
}else{
// don't allow if lenght !=1 , or not a word..., dosomething else, or skip
}

Answer 3

You can split the string on a regular expression that represents a sequence of white spaces and then see how many parts you get. Here's a function to do it:

public static boolean is_word(String s) {
    return (s.length() > 0 && s.split("\\s+").length == 1);
}

System.out.println(is_word("word"));
System.out.println(is_word("two words"));
System.out.println(is_word("word\tabc\txyz"));
System.out.println(is_word(""));

Output :

true
false
false
false

The length check on the input string is required if you want to say that an empty string is not a word, which would seem reasonable.