java password generator stuck

[ImDennis]

so i seem to be stuck on my password generator, anyone got any ideas on how to limit the characters? like i got it to randomly choose but it doesn't limit it to users choice which would be 6

Quote:

import java.util.Scanner;
import java.util.Scanner;
public class PasswordGenerator
{

public static void main(String[] args)

{
// Create Scanner object
Scanner input = new Scanner(System.in);

// create variables
int userChoice;
int randomHex; //holds array

// Tell user what the program will do
System.out.println("This program will randomly generate a password for you");

//ask user how many characters they want (minimum 6, maximum 16)
System.out.println("please enter how many characters do you want in your password (minimum 6, maximum 16)? ");
userChoice = input.nextInt();

//create arrays holding hex chars and secure chars
char[] arrayHex = { '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','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','1','2','3','4','5','6','7','8','9'
,'=','+','-','$','#','@','*','/','^','~' };
//start loop
if(userChoice == 6)
{
//generate random number
randomHex = (int)(Math.random() * arrayHex.length);
System.out.print("your" + randomHex);
//stub
}//end for if
}
//end main
}
//end class

[Tony]

what kind of a loop are you using for "//start loop" ?

[ImDennis]

Tony @ Wed Nov 23, 2011 4:34 pm wrote:

what kind of a loop are you using for "//start loop" ?

i was gonna use if else loop pretty much for user choices between 6 - 12, i noticed i kept getting bugs and i fixed it up a bit, but now im not getting random letters and numbers, just numbers :S its blowing my mind, heres what i got

Quote:

import java.util.Scanner;

/**
* Program Name:D_A_PasswordGenerator.java
* Purpose: generate random password using A-Z and 1-9
* Coder:Denis Aleta
* Date:Nov 23, 2011
*/
import java.util.Scanner;
public class D_A_PasswordGenerator
{

public static void main(String[] args)

{
// Create Scanner object
Scanner input = new Scanner(System.in);

// create variables
int userChoice;
int randomHex; //holds array

// Tell user what the program will do
System.out.println("This program will randomly generate a password for you");

//ask user how many characters they want (minimum 6, maximum 16)
System.out.println("please enter how many characters do you want in your password (minimum 6, maximum 16)? ");
userChoice = input.nextInt();

//create arrays holding hex chars and secure chars
char[] arrayHex = { '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','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','1','2','3','4','5','6','7','8','9'
,'=','+','-','$','#','@','*','/','^','~' };
//start loop
if(userChoice == 12)
{
//generate random number
randomHex = (int)(Math.random() * arrayHex.length);
System.out.println("your randomly generated password is " + randomHex);
//stub


}//finish this next day

}
//end main
}
//end class

edit
----
by if else i meant like if choice -- 6 then print out randomly generated password with 6 randomly generated characters, if else 7 then same thing but 7

[Tony]

ImDennis @ Wed Nov 23, 2011 4:36 pm wrote:

now im not getting random letters and numbers, just numbers :S its blowing my mind,

But... you explicitly cast the choice into a number...

[ImDennis]

Tony @ Wed Nov 23, 2011 4:42 pm wrote:

ImDennis @ Wed Nov 23, 2011 4:36 pm wrote:

now im not getting random letters and numbers, just numbers :S its blowing my mind,

But... you explicitly cast the choice into a number...

yea because i asked the user to choose between 6 and 16, so if he choose 6 then randomly generate a 6 letter/number password so since its a number they're putting in for choice, wouldn't it also be int?

[Tony]

emphasis mine

Quote:

//generate random number
randomHex = (int)(Math.random() * arrayHex.length);
System.out.println("your randomly generated password is " + randomHex);

why do you even have arrayHex ?

[ImDennis]

Tony @ Wed Nov 23, 2011 5:00 pm wrote:

emphasis mine

Quote:

//generate random number
randomHex = (int)(Math.random() * arrayHex.length);
System.out.println("your randomly generated password is " + randomHex);

why do you even have arrayHex ?

arrayhex holds the values, so now you got me thinking, maybe i should make a seperate var for limit so like arrayHexLimit = 16;? and then put it so it randomly generates from arrayHex? but what i was thinking was that math.random would randomly generate from ArrayHex with the users choice?

[Tony]

I suspect that you might be making some assumptions that do not hold. What happens in

code:

randomHex = (int)(Math.random() * arrayHex.length);

lets pretend that arrayHex holds 16 elements, and that Math.random() picks a random value of 0.42. Then the code evaluates to

code:

randomHex = (int)(0.42 * 16); randomHex = (int)(6.72); randomHex = 6;

Is this what you were expecting?

[ImDennis]

Tony @ Wed Nov 23, 2011 5:29 pm wrote:

I suspect that you might be making some assumptions that do not hold. What happens in

code:

randomHex = (int)(Math.random() * arrayHex.length);

lets pretend that arrayHex holds 16 elements, and that Math.random() picks a random value of 0.42. Then the code evaluates to

code:

randomHex = (int)(0.42 * 16); randomHex = (int)(6.72); randomHex = 6;

Is this what you were expecting?

okay can you walk me through this im just learning java, what it is, is essentially a random password generator with user input to choose # of characters, between 6 and 12, so what i was thinking of doing was an if else statement so if the user chooses 6 then it randomly generates 6 characters using the letters and numbers in array, then else if 7 choose 7 randomly and else if 8 generate 8 characters, you know what i mean?

[Tony]

right, but a style of code like

code:

if ( length == 6 ) {    randomLetter();    randomLetter();    randomLetter();    randomLetter();    randomLetter();    randomLetter(); } else ...

seems like a pretty bad idea. For one, you'd just have to type out a lot of the same thing, and it would be too easy to make a mistake somewhere.

It would be best to learn some kind of a looping mechanism, so that you can get that randomLetter once, and repeat that as many times as you want.

[ImDennis]

Tony @ Wed Nov 23, 2011 7:03 pm wrote:

right, but a style of code like

code:

if ( length == 6 ) {    randomLetter();    randomLetter();    randomLetter();    randomLetter();    randomLetter();    randomLetter(); } else ...

seems like a pretty bad idea. For one, you'd just have to type out a lot of the same thing, and it would be too easy to make a mistake somewhere.

It would be best to learn some kind of a looping mechanism, so that you can get that randomLetter once, and repeat that as many times as you want.

hmmm, i guess your right how about something like this?

Quote:

import java.util.Scanner;


//create arrays holding hex chars and secure chars
char[] arrayHex = { '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','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','1','2','3','4','5','6','7','8','9'
,'=','+','-','$','#','@','*','/','^','~' };
//start loop
for(int i = 6; i < 16; i++)
{
System.out.println("Your password is for" + i + is" + arrayHex[i]);
}

}
//end main
}
//end class

would that work and then it' it'll just add? but i guess that loop would contently go on till 16? right, could u tell me the suggested loop? so i can research it?

[Tony]

You are moving in the right direction

A for-loop and using indexes of an array are exactly the parts that you need.

That loop goes up to 16 only because that's what you wrote that example as. It's just as valid to use variables

code:

for(int i = 0; i < someVariable; i++) { ...

[ImDennis]

Tony @ Wed Nov 23, 2011 7:39 pm wrote:

You are moving in the right direction

A for-loop and using indexes of an array are exactly the parts that you need.

That loop goes up to 16 only because that's what you wrote that example as. It's just as valid to use variables

code:

for(int i = 0; i < someVariable; i++) { ...

well i got it kinda, so heres what i got

Quote:

//start loop
for(int i= 0; i<array.length; i++)
{

if (i == 6)
{
System.out.println("Your 6 digit randomly generated password is " + arrayHex );//generate for 6 digits,
}

so since its a for loop and an if inside, cant i do else for 7 8 9 10 11 12 13 14 15 16? also can you please tell me the command to limit the number of characters popping in each loop other then that i think i might have got it

[Tony]

what? Your code seems to have regressed to something that doesn't make sense to me.

[ImDennis]

Tony @ Wed Nov 23, 2011 8:04 pm wrote:

what? Your code seems to have regressed to something that doesn't make sense to me.

okay let me try and explain my thinking to you and maybe u can see what im doing wrong, so i made a for loop right , and then inside that for loop i wanted to do if else (idk if its possible) but then i wanted to put it like if (i == 6)
{
System.out.println("Your" + i " digit randomly generated password is " + arrayHex );
}

so it would generate a password for i which = 6, u know what i mean? if not how do u recommend doin it because thats how i see it the random letters numbers and all that stuff appear but its not limited