'Deleting content of every string after first empty space

How can I delete everything after first empty space in a string which user selects? I was reading this how to remove some words from a string in java. Can this help me in my case?

javastring


Solution 1:[1]

You can use replaceAll with a regex \s.* which match every thing after space:

String str = "Hello java word!";
str = str.replaceAll("\\s.*", "");

output

Hello

regex demo

Like @Coffeehouse Coder mention in comment, This solution will replace every thing if the input start with space, so if you want to avoid this case, you can trim your input using string.trim() so it can remove the spaces in start and in end.

Solution 2:[2]

A simple way to do it can be:

System.out.println("Hello world!".split(" ")[0]);

Solution 3:[3]

// Taking 'str' as your string
// To remove the first space(s) of the string, 
str = str.trim();
int index = str.indexOf(" ");
String word = str.substring(0, index);

This is just one method of many.

str = str.replaceAll("\\s+", " "); // This replaces one or more spaces with one space
String[] words = str.split("\\s");
String first = words[0];

Solution 4:[4]

The simplest solution in my opinion would be to just locate the index which the user wants it to be cut off at and then call the substring() method from 0 to the index they wanted. Set that = to a new string and you have the string they want.

If you want to replace the string then just set the original string = to the result of the substring() method.

Link to substring() method: https://docs.oracle.com/javase/7/docs/api/java/lang/String.html#substring(int,%20int)

Solution 5:[5]

There are already 5 perfectly good answers, so let me add a sixth one. Variety is the spice of life!

private static final Pattern FIRST_WORD = Pattern.compile("\\S+");

public static String firstWord(CharSequence text) {
    Matcher m = FIRST_WORD.matcher(text);
    return m.find() ? m.group() : "";
}

Advantages over the .split(...)[0]-type answers:

  1. It directly does exactly what is being asked, i.e. "Find the first sequence of non-space characters." So the self-documentation is more explicit.

  2. It is more efficient when called on multiple strings (e.g. for batch processing a large list of strings) because the regular expression is compiled only once.

  3. It is more space-efficient because it avoids unnecessarily creating a whole array with references to each word when we only need the first.

  4. It works without having to trim the string.

(I know this is probably too late to be of any use to the OP but I'm leaving it here as an alternative solution for future readers.)

Solution 6:[6]

This would be more efficient

    String str = "Hello world!";
    int spaceInd = str.indexOf(' ');
    if(spaceInd != -1) {
        str = str.substring(0, spaceInd);
    }
    System.out.println(String.format("[%s]", str));

Sources

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Source: Stack Overflow

Solution Source
Solution 1
Solution 2 German
Solution 3
Solution 4 RostSunshine
Solution 5 DodgyCodeException
Solution 6 Yotam

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