how can i make a Password Generator?

Question

i had this idea (it doesn't seem to work well)... its not that random, its just bad... how can make it good or just give me an idea for a good way...

code:

import java.util.*;
public class Main
{

public static void main(String[] args){

//Password Generator:

char[] noCap = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};
char[] withCap = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'};
int[] numbers = {1, 2, 3, 4, 5, 6, 7, 8, 9};

Random r = new Random();
char randomNoCap = noCap[r.nextInt(26)];
char randomWithCap = withCap[r.nextInt(26)];
int randomNumber = numbers[r.nextInt(9)];

System.out.print(randomNumber);
System.out.print(randomWithCap);
System.out.print(randomNoCap);

}

}

Answer 1

How can I do that I pick 3 chars from each array? I tried to write * 3 , and then it converts it into a big number