How good is my password generator code? (Java)

[Paper Cars]

I was tasked with writing a simple program that generates an 8 character password.
The password must contain AT LEAST two UPPERCASE letters and AT LEAST 2 numbers.

Here is what I came up with!

import java.util.*;

class Main {

  public static void generatePassword(){
    String a = Integer.toString(randNum(0,9));
    String b = Integer.toString(randNum(0,9));
    String c = randChar();
    String d = randChar();
    String e = letterNumberDecider();
    String f = letterNumberDecider();
    String g = letterNumberDecider();
    String h = letterNumberDecider();

    System.out.println(buildPassword(a,b,c,d,e,f,g,h));
    
  }
 
  public static void main(String[] args) {

    generatePassword();
    
  }
 
  public static String buildPassword(String a, String b, String c, String d, String e, String f, String g, String h){

    String password = a+b+c+d+e+f+g+h;
    password = shuffleString(password);
    return password;
    
  }
  //String Shuffler
  public static String shuffleString(String string) {
    
    List<String> letters = Arrays.asList(string.split(""));
    Collections.shuffle(letters);
    String shuffled = "";
    
    for (String letter : letters) {
     shuffled += letter;
    }
    
    return shuffled;
    
  }

  //Random Number Generator
  public static int randNum(int min, int max){
    
    int randInt = (int)Math.floor(Math.random()*(max-min+1)+min);
    return randInt;
    
  }

  //random letter generator
  public static String randChar(){

     int capChance = randNum(0,1);
     boolean isCap = false;
      
     Random r = new Random();
     char a = (char) (r.nextInt(26) + 'a');
     String c = Character.toString(a);
    
     if(capChance == 1){
       isCap = true;
     }else{
       isCap = false;
     }

    String randChar;

     if(isCap == true){
       randChar = c.toUpperCase();
     } else {
       randChar = c;
     }
    
     return randChar;
    
  }

  public static String letterNumberDecider(){

    String output = "";
    
    for(int x = 0; x < 3; x++){
      int y = randNum(0,1);
      if(y == 0){
        output = Integer.toString(randNum(0,9));
      }else{
        output = randChar();
      }
    }

    return output;
    
  }

}

Im looking for feedback based on how efficient, and minimal my code is.
For example is there an easier way to do this, does my code feature redundancy, etc.

 

[Theo J]

Why no array

 

[gustavomay]

It's been a while since your post, but I wanted to offer some insight. Your code looks pretty solid for generating a password with specific requirements. It’s clear and functional. However, there are a few suggestions to make it more efficient: Combine Functions: You can simplify randChar() and letterNumberDecider() into a single function to reduce redundancy. Random Object: Instead of creating a new Random object in randChar(), create one instance and reuse it. StringBuilder: Use StringBuilder instead of string concatenation in shuffleString() for better performance. Overall, your approach is great, and it's almost as good as this password generator free I use for my needs.