Method to find any repeating patterns inside a String. Output will show each repeating pattern and how many times it repeats.

Facebook.java

public class StringPatterns {
    //This is used to convert all message contents into original text. It converts the unicode automatically.
	private String decodeString(String text) {
		Charset targetEncoding = Charset.forName("ISO-8859-1");
		String  unescapeText   = StringEscapeUtils.unescapeJava(text);
		return new String(unescapeText.getBytes(targetEncoding), StandardCharsets.UTF_8);
	}

}

RandomText.java

public void usungApache() {
 
    int length = 10;
    boolean useLetters = true;
    boolean useNumbers = false;
    String generatedString = RandomStringUtils.random(length, useLetters, useNumbers);
 
    System.out.println(generatedString);
} 

	static String getAlphaNumericString(int n) {
		byte[] array = new byte[256];
		new Random().nextBytes(array);
		String randomString = new String(array, StandardCharsets.UTF_8);
		StringBuffer r = new StringBuffer();
		for (int k = 0; k < randomString.length(); k++) {
			char ch = randomString.charAt(k);
			if (((ch >= 'a' && ch <= 'z')
				 || (ch >= 'A' && ch <= 'Z')
				 || (ch >= '0' && ch <= '9'))
				&& (n > 0)) {
				r.append(ch);
				n--;
			}
		}
		return r.toString();
	}

	public void givenUsingJava8_whenGeneratingRandomAlphabeticString_thenCorrect() {
		int    leftLimit          = 97; // letter 'a'
		int    rightLimit         = 122; // letter 'z'
		int    targetStringLength = 10;
		Random random             = new Random();

		String generatedString = random.ints(leftLimit, rightLimit + 1)
									   .limit(targetStringLength)
									   .collect(StringBuilder::new, StringBuilder::appendCodePoint, StringBuilder::append)
									   .toString();

		System.out.println(generatedString);
	}

StringPatterns.java

import java.util.HashMap;
import java.util.LinkedList;
import java.util.Map;

class StringPatterns {
	private void checkForPattern(String userString) {
		String               buildString;
		LinkedList<String>   patterns    = new LinkedList<>();
		int                  size        = userString.length();
		int                  hits;
		int                  newSize;
		String[]             coreString  = new String[size];
		Map<String, Integer> hitCountMap = new HashMap<>();

		for (int x = 0; x < size; x++) {
			coreString[x] = userString.substring(x, x + 1);
		}

		for (int index = 0; index < size - 1; index++) {
			buildString = coreString[index];
			for (int x = index + 1; x < size; x++) {
				buildString = buildString + coreString[x];
				patterns.add(buildString);
			}
		}

		for (String pattern : patterns) {
			String check = userString.replaceFirst(pattern, "");
			if (check.contains(pattern)) {
				newSize = userString.replaceAll(pattern, "").length();
				hits    = (size - newSize) / pattern.length();
				hitCountMap.put(pattern, hits);
			}
		}

		for (String pattern : hitCountMap.keySet()) {
			System.out.println("Pattern: " + pattern +
							   " repeated " + hitCountMap.get(pattern) +
							   " times.");
		}
	}
}