Thread: How to convert password to md5?

I want to convert the input in a jpasswordfield to md5 but the problem is I don't know how

It's not difficult, you just need the magic incantation in Java.

Let me google that for you

MessageDigest is what you need. It looks a bit daunting at first, but most times you use it it'll be very little code: just a line or two.

Hello A4Andy,

I am going to assume you know how to get the value in the JPassowrdField already. As for converting that to md5, check out Message Digest.

too bad I don't know how to get the value of JPasswordField using JButton as the trigger. I already knew converting from String to md5 but not from JPasswordField to md5.

I tried this code but it didn't work

	public class HandlerClass1 implements ActionListener { 
		public void actionPerformed(ActionEvent event)
		{
 
			char[] pass = pfPword.getPassword();
			String s= new String(pass);
		    MessageDigest m;
			try {
				m = MessageDigest.getInstance("MD5");
				m.update(s.getBytes(),0,s.length());
				System.out.println("MD5: "+new BigInteger(1,m.digest()).toString(16));
			} catch (NoSuchAlgorithmException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
 
		}
	}

I'm getting a null pointer exception

I'm getting a null pointer exception

Copy and paste it. You've read the API doc for getPasswordField and seen that it can throw a NPE?

There's not much in there that could be throwing an NPE. Which is line 100 in db.java? If you've edited the file since you posted the stack trace, make sure you select the line on which the Exception is thrown in your latest source.

public class HandlerClass1 implements ActionListener { 
		public void actionPerformed(ActionEvent event)
		{
 
		100	char[] pass = pfPword.getPassword();
		101	String s= new String(pass);
		102   MessageDigest m;
		103	try {
		104		m = MessageDigest.getInstance("MD5");
		105		m.update(s.getBytes(),0,s.length());
		106		System.out.println("MD5: "+new BigInteger(1,m.digest()).toString(16));
		107	} catch (NoSuchAlgorithmException e) {
		108		// TODO Auto-generated catch block
		109		e.printStackTrace();
		110	}
 
		}
	}

Here is my whole db class

import java.awt.*;
import java.awt.event.*;
import java.security.*;
import java.math.*;
 
import javax.swing.*;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;
 
public class db extends JPanel {
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	private JLabel lbldbURL,lbldbName,lbldbUName,lbldbPword;
	private JTextField txtdbURL,txtdbName,txtdbUname;
	private JPasswordField pfPword;
	private JButton saveButton;
 
	public db() 
	{
		this.setBackground(Color.WHITE);
		setLayout(null);
		Font serif = new Font("serif",Font.PLAIN,14);
		////////////
		//Labels
		////////////
		//
		//Database URL
		JLabel lbldbURL = new JLabel("Database URL:");
		lbldbURL.setBounds(290, 110, 170, 20);
		lbldbURL.setFont(serif);
		add(lbldbURL);		
		//
		//Database Name
		JLabel lbldbName = new JLabel("Database Name:");
		lbldbName.setFont(serif);
		lbldbName.setBounds(280, 150, 170, 20);
		add(lbldbName);
		//
		//Database User name
		JLabel lbldbUName = new JLabel("Database Username:");
		lbldbUName.setFont(serif);
		lbldbUName.setBounds(250, 190, 170, 20);
		add(lbldbUName);
		//
		//Database Password
		JLabel lbldbPword = new JLabel("Database Password:");
		lbldbPword.setFont(serif);
		lbldbPword.setBounds(255, 230, 170, 20);
		add(lbldbPword);
		////////////////
		//text field
		///////////////
		//
		//text database URL
		JTextField txtdbURL  = new JTextField();
		txtdbURL.setFont(serif);
		txtdbURL.setBounds(410, 110, 170, 20);
		add(txtdbURL);
		//
		//text database name 
		JTextField txtdbName  = new JTextField();
		txtdbName.setFont(serif);
		txtdbName.setBounds(410, 150, 170, 20);
		add(txtdbName);
		//
		//Database User textfield
		JTextField txtdbUName = new JTextField();
		txtdbUName.setFont(serif);
		txtdbUName.setBounds(410, 190, 170, 20);
		add(txtdbUName);
		//
		//password field database password 
		JPasswordField pfPword  = new JPasswordField();
		pfPword.setFont(serif);
		pfPword.setBounds(410, 230, 170, 20);
		add(pfPword);
		//
		//Save Button
		JButton saveButton  = new JButton("Save");
		saveButton.setBounds(410, 260, 170, 20);
		add(saveButton);
		////////////
		//Action Listener
		////////////
		HandlerClass1 handler1 = new HandlerClass1();
		saveButton.addActionListener(handler1);
	}
	static class AL implements ActionListener{
		public void actionPerformed(ActionEvent event)
		{			
		}
	}
	public class HandlerClass1 implements ActionListener  
	{ 
		public void actionPerformed(ActionEvent event) 
		{
			char[] pass = pfPword.getPassword();
			String s= new String(pass);
			MessageDigest m;
			try 
			{
				m = MessageDigest.getInstance("MD5");
				m.update(s.getBytes(),0,s.length());
				System.out.println("MD5: "+new BigInteger(1,m.digest()).toString(16));
			} 
			catch (NoSuchAlgorithmException e) 
			{
				e.printStackTrace();
			}
		}
	}	
}

Heheh - there's another thread on the forum today about this. How many times have you declared pfPword?

what do you mean I think only once.

search your text file for "JPasswordField". It should be in there only twice - once when you declare the reference pfPword and once when you use the JPasswordField constructor. I count more than two in your 'whole db class' post:
http://www.javaprogrammingforums.com...html#post42561

it's now working well

import java.awt.*;
import java.awt.event.*;
import java.security.*;
import java.math.*;
 
import javax.swing.*;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;
 
public class db extends JPanel {
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	private JLabel lbldbURL,lbldbName,lbldbUName,lbldbPword;
	private JTextField txtdbURL,txtdbName,txtdbUname;
[COLOR="#FF0000"]	private JPasswordField pfPword = new JPasswordField();[/COLOR]
	private JButton saveButton;
 
	public db() 
	{
		this.setBackground(Color.WHITE);
		setLayout(null);
		Font serif = new Font("serif",Font.PLAIN,14);
		////////////
		//Labels
		////////////
		//
		//Database URL
		JLabel lbldbURL = new JLabel("Database URL:");
		lbldbURL.setBounds(290, 110, 170, 20);
		lbldbURL.setFont(serif);
		add(lbldbURL);		
		//
		//Database Name
		JLabel lbldbName = new JLabel("Database Name:");
		lbldbName.setFont(serif);
		lbldbName.setBounds(280, 150, 170, 20);
		add(lbldbName);
		//
		//Database User name
		JLabel lbldbUName = new JLabel("Database Username:");
		lbldbUName.setFont(serif);
		lbldbUName.setBounds(250, 190, 170, 20);
		add(lbldbUName);
		//
		//Database Password
		JLabel lbldbPword = new JLabel("Database Password:");
		lbldbPword.setFont(serif);
		lbldbPword.setBounds(255, 230, 170, 20);
		add(lbldbPword);
		////////////////
		//text field
		///////////////
		//
		//text database URL
		JTextField txtdbURL  = new JTextField();
		txtdbURL.setFont(serif);
		txtdbURL.setBounds(410, 110, 170, 20);
		add(txtdbURL);
		//
		//text database name 
		JTextField txtdbName  = new JTextField();
		txtdbName.setFont(serif);
		txtdbName.setBounds(410, 150, 170, 20);
		add(txtdbName);
		//
		//Database User textfield
		JTextField txtdbUName = new JTextField();
		txtdbUName.setFont(serif);
		txtdbUName.setBounds(410, 190, 170, 20);
		add(txtdbUName);
		//
		//password field database password 
		pfPword.setBounds(410, 230, 170, 20);
		add(pfPword);
		//
		//Save Button
		JButton saveButton  = new JButton("Save");
		saveButton.setBounds(410, 260, 170, 20);
		add(saveButton);
		////////////
		//Action Listener
		////////////
		HandlerClass1 handler1 = new HandlerClass1();
		saveButton.addActionListener(handler1);
	}
	static class AL implements ActionListener{
		public void actionPerformed(ActionEvent event)
		{			
		}
	}
	public class HandlerClass1 implements ActionListener  
	{ 
		public void actionPerformed(ActionEvent event) 
		{
			char[] pass = pfPword.getPassword();
			String s= new String(pass);
			MessageDigest m;
			try 
			{
				m = MessageDigest.getInstance("MD5");
				m.update(s.getBytes(),0,s.length());
				System.out.println("MD5: "+new BigInteger(1,m.digest()).toString(16));
			} 
			catch (NoSuchAlgorithmException e) 
			{
				e.printStackTrace();
			}
		}
	}	
}

My code before was actually a bad practice?

Glad you got it working. It's not so much 'bad practice' as just wrong. You declared two references to JPasswordField, only one of which you assigned to a JPasswordField object. The other one's value is by default null. It's quite a common source of error - the other guys were talking about it here yesterday as 'shadowing' - more than one variable with the same name. The two variables may have completely different scope (where they can be 'seen' from in the code), or may even overlap. The compiler decides which one you mean (usually the most *local* one), but you may have last assigned to the other one ... boom.

Not always easy to spot when you've done it either. If you find yourself thinking "that's not null, I just set it there...", it's worth checking to see if you've declared the reference more than once.