How to generate a random password in Java

#java #random

Hi folks!
I hope you all are fine! Today, I want to show you how to generate a random password.
First of all, we need to create the class and define the valid characters for our password.

Well, lets consider characters 0 to 9, A to Z, capital and lower cases.
We can call the class PasswordGenerator.

public class PasswordGenerator {
    public static void main(String[] args) {
        String validChars = "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,0,1,2,3,4,5,6,7,8,9,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[] chars = validChars.split(",");
    }
}

Now, lets create the method that will generate the password. And this, is going to return a String. And we can call it with an int parameter, and lets call it length.
This method will look like this:

public static String generatePassword(int length) {
 //code here
}

Now, inside this method, lets write the real code that generates it for us!

public static String generatePassword(int passLength) {

        //Setting the valid charaters for the generated password
        String validChars = "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,0,1,2,3,4,5,6,7,8,9,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";

        //Creating an array by splitting the above String by the comma
        String[] chars = validChars.split(",");

        //Create the String that will store each charater that will be chosen
        StringBuilder password = new StringBuilder();

        //This object will be the random that will "bounce" between the chars array.
        //Don't forget to import the Random class from util package (java.util.Random).
        Random r = new Random();

        //This loop will make the Random object (r) bounce between the array many times
        //The quantity of times is called "passLength"
        for (int i = 0; i < passLength; i++){
            password.append(chars[r.nextInt(chars.length)]);
        }

        return password.toString();
}

And now, we have to call this method inside the main method. Lets do it.

public static void main(String[] args) {
        //In this example, we generate a 20 lengthened password
        //But you can set the length you want
        System.out.println(generatePassword(20));

    }

Well, heres is the full code:

import java.util.Random;


public class PasswordGenerator {

    public static void main(String[] args) {
        //In this example, we generate a 20 lengthened password
        //But you can set the length you want
        System.out.println(generatePassword(20));

    }

    public static String generatePassword(int length) {

        String validChars = "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,0,1,2,3,4,5,6,7,8,9,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";
        String[] chars = validChars.split(",");

        StringBuilder password = new StringBuilder();

        Random r = new Random();

        for (int i = 0; i < length; i++){
            password.append(chars[r.nextInt(chars.length)]);
        }

        return password.toString();
    }


}

Lets compile the code.