有没有办法可以逐步将字符串的某些部分设置为数组？ （JAVA）

Question

For example, String letters = "fourgooddogsswam";

Is there a way I can scan the string from left to right 4 characters at a time so that I can set(four ourg urgo rgoo good oodd oddo ddog dogs ogss gssw sswa swam) into a string array? I tried using loops but I'm having difficulties getting it to work properly.

Thanks!

public static String[] findWordsOfLength(String letters, int wordSize) {
    if(letters == null) {
        return null;
    }

    int size = letters.length();
    int wordMax = size - wordSize + 1;
    if(size < wordMax || wordMax <= 0) {
        return new String[0];
    }

    int j = 0;
    String[] result = new String[wordMax];

    for (int i = 0; i < wordMax; i++) {
        result[j ++] = letters.substring(i, i + wordSize);
    }

    return result;
}

Answer 1

Use a while loop and arraylist like this,

    String hello = "fourgooddogsswam"; 

    List<String> substrings = new ArrayList<>();

    int i = 0;
    while (i + 4 <= hello.length()) {

        substrings.add(hello.substring(i, i + 4));
        i++;

    }

    for (String s : substrings) {

        System.out.println(s);

    }

If you want to do this without arraylist just make a string array with size YOURSTRING.length() - (WHATEVERSIZE - 1);

Example

    String hello = "fourgooddogsswam"; 

    String[] substrings = new String[hello.length() - 3];

    int i = 0;
    while (i + 4 <= hello.length()) {

        substrings[i] = hello.substring(i, i + 4);
        i++;

    }

    for (String s : substrings) {

        System.out.println(s);

    }

Answer 2

Just another way to do this.

import java.io.*;
import java.util.regex.Pattern;
import java.util.regex.Matcher;

public class Test {

 public static void main(String args[]) {
  String str = new String("fourgooddogsswam");

  Pattern pattern = Pattern.compile(".{4,4}");
  Matcher matcher = pattern.matcher(str);

  while (matcher.find()) {
   System.out.println(matcher.group(0));
  }
 }
}

Will print:

four
good
dogs
swam

PS Yes, we all hate regex... but it does the work ;)