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How to create a Java 2-Step authentication on Java 8?

Hello everyone at StackOverflow,
I will be asking a question that I'm confused about and searched for hours for, it's to put a 2-Step authentication on a Java program, what I want is that is send a generated code to a login page like the one I created below.
package log;
import javax.swing.JOptionPane;
public class Login {
public static void main(String args[]) {
String username = JOptionPane.showInputDialog("Enter your username");
String password = JOptionPane.showInputDialog("Enter your password");
if (
username != null && password != null &&
(
(username.equals("g17") && password.equals("ire35")) ||
(username.equals("ree") && password.equals("melikejava")) ||
(username.equals("citizenzap") && password.equals("javarules23"))||
(username.equals("devs") && password.equals("password"))
)
)
{
JOptionPane.showMessageDialog(null, "Logged in!" );
} else {
JOptionPane.showMessageDialog(null, "Incorrect username or password! Try again later." );
}
}
}
Everything is fine with the code above, it's just that I want to send a randomly generated code to a phone number, like as I said before a 2-Step verification. Like Google has or Microsoft and etc. For example: You write a phone number, 123-456-7890, then it sends a code to the phone number and it's says something like Your code is 178634 then you write it into the input box, then it checks if it was the code it sent.
If the question I said is not specific enough or something like that please tell me.
Thanks and keep on coding!
-CitizenZap

First, I suggest you put your data in map, combine username, password, phoneNumber into one class, like UserInfo. Because you need to bind phoneNumber to user, or any phoneNumber after login is acceptable.
Then, you replace
{
JOptionPane.showMessageDialog(null, "Logged in!" );
}
with
String newPhoneNumber = null;
{
newPhoneNumber = JOptionPane.showInputDialog("Enter your phone number");
}
You need to check if newPhoneNumber equals with the phoneNumber bind to the user.
// this should be in a while(true) loop
if (newPhoneNumber.equals(phoneNumber)) {
sendSms(phoneNumber);
String code = JOptionPane.showInputDialog("Enter your code");
boolean result = validateAuthorizationCode(code); // here you validate the code
if (result) {
JOptionPane.showMessageDialog(null, "Logged in!" );
} else {
JOptionPane.showMessageDialog(null, "Wrong code!" );
}
} else {
noticeWrongNumber(newPhoneNumber); // tell him the number is wrong, please reinput.
}

How to return properly in if else and avoid "void" for errors about return

I am having a hard time how to return into specific variable or how to return without getting any error base on my program.
class Facebook {
public static void main(String[]args){
String user = JOptionPane.showInputDialog(null,"Enter Username: ");
String pass = JOptionPane.showInputDialog(null,"Enter Password: ");
if(user.equals("jas")&&(pass.equals("bsit"))){
JOptionPane.showMessageDialog(null,"Welcome "+ user);
Selection Class = new Selection();
Selection.Selection1();
}
else if (!user.equals("jas")||(!pass.equals("bsit"))) {
JOptionPane.showMessageDialog(null,
"Invalid Username or Password",
"Wrong Authentication",
JOptionPane.ERROR_MESSAGE);
System.exit(0);
}
}
}
class Selection{
public Selection1(){
try{
String select = JOptionPane.showInputDialog("[1]Home\n[2]Profile\n[3]Logout");
int numbers = Integer.parseInt(select);
if (numbers == 1){
JOptionPane.showMessageDialog(null,"Mang Tani: Lumakas ang hanging amihan halos nilipad ang mga bubong ng mga bahay\n\nJessica Soho: Isang sikat na pagkain sa davao inubos ng kabataan \n\n Boying Remulla: Walang pasok dahil sa malakas na ulan\n#WalangPasok.");
return select;
}
else if (numbers == 2){
JOptionPane.showMessageDialog(null,"Name: Ralph Jasper \n\n Age: 17 \n\n Address: Tierra Nevada, General Trias, Cavite");
}
else if (numbers == 3){
}
}
catch (NumberFormatException nfe){
JOptionPane.showMessageDialog(null,"Please input only numbers","Invalid Input",JOptionPane.ERROR_MESSAGE);
}
}
}

1) you want a method with a return value of a string
Replace
public Selection1(){
with
public String select()
2) all "paths" of a non-void method must result in a return statement. This does not mean a return statement needs to be inside any if else's, but you do need to return something within the method.
Suggestion: declare a String result = ""; outside of the try catch, return it after, outside of the catch, and assign it to your JOptionPane value in between like result = JOptionPane...
3) I'm assuming you actually want that value that's returned?
Selection selector = new Selection();
String selected = selector.select();
// TODO use that value
Notice: Java naming conventions -- methods are lowerCase, classes are UpperCase.

How do I create a login form in Java using file stream?

Hello i am a new java student i have been working on a library system containing ( users - library workers and books ) so i am trying to create a log in form i already have an array list but i did a file stream ( to clarify i let the new user to register and his/her information will be saved to the file like this ID Name Password Age ) so i have tried to do something as this method in the library users class
private Scanner x;
private String user_name , password ;
public void openfile(){
try {x= new Scanner (new File ("E:\\javaapplication1
\\test\\professors.txt"));
}
catch(Exception e){
System.out.println("couldn't find file");
}
}
public void checklog ( String username , String password ){
String a , b ,c ,d ;
while(x.hasNext()){
a = x.next();
b = x.next();
c = x.next();
d = x.next();
if ( b == username ||c == password ){
System.out.println("Loggin successful ");
}
else
System.out.println("Loggin failed wrong id or password ");
break;
and then call it like this in the main with the full code
System.out.println ("Enter your name ");
check_name = reader.next();
System.out.println ("Enter your password ");
check_password =reader.next();
lib_us professor ;
professor = new lib_us();
professor.openfile();
professor.checklog(check_name, check_password);
i get all passwords wrong i save them like 4 id name password and age that's why i created a b c and d ...
i am still new in this kind of log in forms so please specify me a solution and if you need the whole code please ask for it :)

So in your checkLog() method you have the statement if(b == username || c == password) should be if(b.equals(username) && c.equals(password)) OR if(b.equalsIgnoreCase(username) && c.equalsIgnoreCase(password)) for case sensitive or not (use the equals() method for case sensitivity or the equalsIgnoreCase() method for non case sensitivity).
Understand why that is? Because in your original statement you are saying only one of them has to be true in order for it to be a successful login. With the revised one both of them must be true. Also you should not use the operator == to compare two strings to see if they are the same string. That will only compare their addresses.
EDIT:
If your file is kind of like what is shown below:
12 Name Pass 12
13 Namez Passz 13
14 Namezz Passzz 14
Try this code to read it in and compare:
private Scanner x;
private String user_name, password;
public void openFile()
{
try
{
x = new Scanner(new File("FILE PATH"));
}
catch(Exception e)
{System.out.println("Couldn't find file"); System.exit(0);}
}
public boolean checklog(String username, String password)
{
String temp;
String[] info;
while(x.hasNext())
{
temp = x.nextLine();
info = temp.split(" ");
//info[0] = id, info[1] = username, info[2] = password, info[3] = age;
//Right here that means the username and password is correct
if(info[1].equals(username) && info[2].equals(password))
{
System.out.println("Login Successful");
return true;
}
}
System.out.println("Login failed wrong id or password");
return false;
}

password check using hashmap

I want to check username and password using this action listener method
but I always get Wrong password!
public void actionPerformed(ActionEvent arg0) {
String uN = usernameFiled.getText();
String pass = passwordField.getPassword().toString();
//
if (uN.isEmpty() || pass.isEmpty()){
JOptionPane.showMessageDialog(LoginPage.this, "Fields should not be empty!", "Error", JOptionPane.ERROR_MESSAGE);
return;
}
HashMap<String, User> users = UserDAO.getInstance().getUsers();
User temp = users.get(uN);
if (temp.getPassword().equals(pass)){
JOptionPane.showMessageDialog(LoginPage.this, "Login successfull", "Success", JOptionPane.INFORMATION_MESSAGE);
}
else {
JOptionPane.showMessageDialog(LoginPage.this, "Wrong username or password", "Error ", JOptionPane.ERROR_MESSAGE);
}
}
});
What is the problem of code??

JPasswordField#getPassword returns the text contained in this TextComponent in char[]. char[].toString() does not return the string value, array.toString actually returns the name of the variable and hascode.
you should call new String(passwordField.getPassword()) or String.valueOf(passwordField.getPassword())
try -
String pass = new String(passwordField.getPassword());
or
String pass = String.valueOf(passwordField.getPassword());

passwordField.getPassword() return char[]. So by calling toString() give you the object string of char[].So, The statement you are using, do not give you password.
String pass = passwordField.getPassword().toString();
Use it in following way.
String pass = new String(passwordField.getPassword());

Login jframe password control with text file

I have a login frame, That has two different login mode, "User" and "Admin".
My problem is in admin mode (when select admin from jcombobox),
When i select admin, my first textfield should fill with "Administration" automatically and did, And in my jpasswordfiled, It should search it's password number from text file (that is 2).
But, Not accept in admin mode:
public class LoginFrame extends javax.swing.JFrame implements ActionListener {
private String username;
private char[] Password;
...
private void LoginButtonActionPerformed(java.awt.event.ActionEvent evt) {
try {
username = String.valueOf(jTextField1.getText());
Password = jPasswordField1.getPassword();
if (jComboBox1.getSelectedIndex() == 2) {
if (adminCanGoNext2()) {
goAdminMainPage(); // Execute work
} else {
ErrorMessageLabel.setText("Did Not Match");
}
}
} catch (Exception e) {
ErrorMessageLabel.setText("Enter Correct Input");
}
public boolean adminCanGoNext2() throws IOException {
FileReader fr = new FileReader("LoginInformation.txt");
BufferedReader br = new BufferedReader(fr);
String line;
while( (line = br.readLine())!= null ){
if(line.startsWith("Admin")){
char[] charedPass=line.toCharArray(); // char password that read from file
System.out.println("readed password is: "+ charedPass.toString());
if(Arrays.equals(charedPass, Password)){
return true;
}
}
}
return false;
}
public void goAdminMainPage() {
System.out.println("Go ");
}
...
#Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == jComboBox1) {
if (jComboBox1.getSelectedIndex() == 2) {
jTextField1.setText("Administration");
}
}
}
}
Login Information.txt file:
Admin 2
271 tes tt Male 2013/05/30
458 tttt uuuu Female 2013/05/30
Now, When i select admin mode, my jtextfield1 text is "Administration" perfectly,
But when i try number "2" for passwordfield, and clicked to login button, make no change!

You are comparing a String with a character array (and they are always found non-equal obviously).
You have to convert the password read from the file into a character array using toCharArray() and then compare the resulting array with the character array returned by JPasswordFields gePassword() method. For easy comparing of arrays you can use the utility methods of java.util.Arrays.
See, also, this short demo.
EDIT:
Please note, that storing passwords in String variables is not advisable due to security concerns. (Of course storing passwords in files in clear-text is probably an even greater security risk.)
The "How to Use Password Fields" section of the Java Tutorials might be a good source of info and directions to get you started.