StringUtil.java

package noobchain;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;

import com.google.gson.GsonBuilder;

public class StringUtil {
	
	//Applies Sha256 to a string and returns the result. 
	public static String applySha256(String input){
		
		try {
			MessageDigest digest = MessageDigest.getInstance("SHA-256");
	        
			//Applies sha256 to our input, 
			byte[] hash = digest.digest(input.getBytes(StandardCharsets.UTF_8));
	        
			StringBuilder hexString = new StringBuilder(); // This will contain hash as hexidecimal
			for (byte b : hash) {
				String hex = Integer.toHexString(0xff & b);
				if (hex.length() == 1) hexString.append('0');
				hexString.append(hex);
			}
			return hexString.toString();
		}
		catch(Exception e) {
			throw new RuntimeException(e);
		}
	}
	
	//Short hand helper to turn Object into a json string
	public static String getJson(Object o) {
		return new GsonBuilder().setPrettyPrinting().create().toJson(o);
	}
	
	//Returns difficulty string target, to compare to hash. eg difficulty of 5 will return "00000"  
	public static String getDifficultyString(int difficulty) {
		return "0".repeat(difficulty);
	}
	
	
}