Choosing a random vector and choosing a random value

[Michail]

Hi,

I'm working on a program that can generate random passwords. I've got a JComboBox in which the user can choose the PasswordLength. Then, when the user clicks on the Generate-button, a random password is generated.

I've got 3 vectors:

The first vector contains digits from 0 to 9.
The second vector contains the alphabet in lower case.
The third vector contains the alphabet in upper case.

When the user presses the Generate-button, the method GeneratePassword() is invoked. But I don't exactly know how to write that method.

For every place in the password, the program must choose a random vector out of the three vectors mentioned above, to pick a value from.. and then choose a random value. For the next place in the password, this operation must be repeated.

The method GeneratePassword() is empty now:

     public String GeneratePassword() {
          for(int i = 0; i < Integer.parseInt((String)cPasswordLength.getSelectedItem()); i++) {
          }
     }

Using a for-statement, the method should go to the next place in the password to be generated.

So, anyone wants to help?

[ComputerJy]

import java.util.Random;
import java.util.Vector;

/**
 *
 * @author ComputerJy
 */
public class PasswordCreator
{
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args)
    {
        PasswordCreator pc=new PasswordCreator();
        System.out.printf("You password is: %s\n", pc.getPassword(10));
    }
    
    private Vector<Character> vChar;
    private Vector<Character> vCaps;
    private Vector<Character> vNumbers;
    private Random rand;
    
    private void InitVectors()
    {
        vChar=new Vector<Character>();
        for(char c='a';c<='z';c++)
        {
            vChar.add(new Character(c));
        }
        vCaps=new Vector<Character>();
        for(char c='A';c<='Z';c++)
        {
            vCaps.add(new Character(c));
        }
        vNumbers=new Vector<Character>();
        for(int i=0;i<10;i++)
        {
            vNumbers.add(Integer.toString(i).charAt(0));
        }
        rand=new Random();
    }
    
    public String getPassword(int passwordLength)
    {
        if(vChar==null||vCaps==null||vNumbers==null)InitVectors();
        StringBuilder sb=new StringBuilder();
        for(int i=0;i<passwordLength;i++)
        {
            switch(rand.nextInt(3))
            {
            case 0:
                sb.append(vChar.elementAt(rand.nextInt(vChar.size())));
                break;
            case 1:
                sb.append(vCaps.elementAt(rand.nextInt(vCaps.size())));
                break;
            case 2:
                sb.append(vNumbers.elementAt(rand.nextInt(vNumbers.size())));
                break;
            }
        }
        return sb.toString();
    }
    
}