如何使用正则表达式查找字符串中子字符串的不同出现？

Question

Basically what I want to do is this:

String mystr = "hello Benjamin Benny Benn hey hey";
String pattern = "Be";

Desired list = {"Benjamin","Benny","Benn"};

I know how to do this in a really simple way. What I am looking for is a fast way to do it based on regex or whatever that works for me. I want a list of all sub-strings(words) starting with a specific pattern.

Answer 1

Use this regex:

Be\w+

What it does?

It matches all the words that start with Be

If you want word starting with anything else, simply do this:

String startsWith="Be"; // change this to match your requirements

String regexPattern=startsWith+"\\w+"; //escaped backslash

Now, you can substitute anything in startsWith , so you can match words that starts with a specific string.

Note: You'll need to escape the backslash in java. So \\ becomes \\\\

Answer 2

Try,

String mystr = "hello Benjamin Benny Benn hey hey";
String pattern = "Be";
for(String str : mystr.split("\\s")){
    if(str.matches(pattern+"\\w+")){
         System.out.println("Matched "+str);
         // Add the str to list
    }
}

Here,

\\\\w+ indicates -
word characters (az, AZ, 0-9, _) (1 or more times (matching the most amount possible))

\\\\s indicates -
whitespace (\\n, \\r, \\t, \\f, and " ")

Answer 3

I found this answer which helped me a lot:

String yourString = "hi #how are # you";
Matcher matcher = Pattern.compile("#\\s*(\\w+)").matcher(yourString);    
while (matcher.find()) {
  System.out.println(matcher.group(1));
}

This way even if your pre-string is separated from the main string it works fine.