Convert 2 chars to a string

I have 2 chars I need converting to a string. I can convert one no problem but how do I turn 2 randomly generated chars into one string? Here is my code so far, the aim of my program is to generate two chars at random and return them:

import java.util.Random;
public class PasswordGenerator {

    Random rand = new Random();

    public String uppercaseLetters() {
    char char1;
    char char2;
    String alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    String result;


    char1 = alphabet.charAt(rand.nextInt(25));
    char2 = alphabet.charAt(rand.nextInt(25));


    result = String.valueOf(char1, char2);
    return result;
    }

    public static void main(String[] args) {

    PasswordGenerator pg = new PasswordGenerator();

    System.out.println(pg.uppercaseLetters());

    }

}

Answer

A String concatenated with a char is a String¹. So you could do,

result = String.valueOf(char1) + char2;

or something like

result = "" + char1 + char2;

Also, I’d really prefer to use a StringBuilder. I’d also make the length an argument, move the Random and String out of the method.

class PasswordGenerator {
    final Random rand = new Random();
    final static String upperCase = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

    public String uppercaseLetters(int len) {
        StringBuilder sb = new StringBuilder(len);
        for (int i = 0; i < len; i++) {
            sb.append(upperCase.charAt(rand.nextInt(upperCase.length())));
        }
        return sb.toString();
    }
}

Then you could call it like pg.uppercaseLetters(2) or pg.uppercaseLetters(4) and get n letters (instead of 2).

^{1_{char is an integral value in Java, so char+char is an int.}}