Hi there, need help for this program...thx!

Question

Hi there guys,
I have created this applet program that requires a user to login with a user no, and a password. I am using arrays as to store the defined variables,(as required by my project supervisor). My problem here is that when the arrays are declared in class validateUser(), the program would run fine, but i cant login and i get a NullPointerException error. if the arrays are located in actionPerformed, i get a 'cannot resolve symbol' error for the method 'get' and 'if (Admin.equals(admins.get(i).toString())) ' as well as 'if (Password.equals(passwordsget(i).toString())) '. I am not very effecient in java, hence the untidy program (and i have to admit, it isnt any good), so sorry for any inconvenience caused. Once agani thx in advance ;)
here are my codings :
import java.applet.Applet;
import java.awt.*;
import java.awt.image.*;
import java.awt.event.*;
import java.io.*;
import java.net.URL;
import java.net.*;
import javax.swing.*;
import java.lang.*;
import java.util.Vector;
public class eg31662 extends Applet implements ActionListener
     Panel panel1, panel2, panel3, panel4, panel5;
     Button login, enter;
     Label inst, top, admin, pass, fieldlabel;
TextField adminF, passF, field;
String Admin, Password;
Vector admins, passwords;
     Thread thread = null;
     boolean status = false;
          public class validateUser extends Applet
               String[] admins = {"User1", "User2", "User3"};
               String[] passwords = {"P1", "P2", "P2"};
     public void init()
          setLayout (new BorderLayout());
          panel1 = new Panel(new FlowLayout());
          panel2 = new Panel(new FlowLayout());
          //login button
          login = new Button("Login");
          //instruction
          inst = new Label("Please type in your User no. and the given password in order to proceed");
          //label
          top = new Label("Login login");
          admin = new Label("Admin No :");
          pass = new Label("Password :");
          //input textfields
          adminF = new TextField(8);
          passF = new TextField(10);
          passF.setEchoChar('*');
          panel1.setBackground(Color.gray);
          panel2.setBackground(Color.orange);
          panel2.add(admin);
          panel2.add(adminF);
          panel2.add(pass);
          panel2.add(passF);
          panel2.add(login);
          panel2.add(inst);
          panel1.add(top);
          add(panel1, BorderLayout.NORTH);
          add(panel2, BorderLayout.CENTER);
          login.addActionListener(this);
          setSize(500,400);
     void mainpage()
          boolean flag = true;
          setLayout (new BorderLayout());
          panel1 = new Panel(new FlowLayout());
          panel2 = new Panel(new FlowLayout());
          top = new Label("Welcome");
          enter = new Button("Enter");
          panel2.setBackground(Color.orange);
          panel1.setBackground(Color.gray);
          fieldlabel = new Label("Type something here :");
          field = new TextField(20);
          add(panel1, BorderLayout.NORTH);
          add(panel2, BorderLayout.CENTER);
          panel2.add(fieldlabel);
          panel2.add(field);
          enter.addActionListener(this);
     public void start() {
          if(thread == null) {
               status = true;
     public void stop() {
          status = false;
     public void run() {
          while(status == true) {
               try {
                    thread.sleep(50);
               catch(InterruptedException ie) {
               repaint();
          thread = null;
     public void actionPerformed(ActionEvent ev)
               //String[] admins = {"User1", "User2", "User3"};
               //String[] passwords = {"P1", "P2", "P3"};
          if(ev.getSource() == login)
               Admin = adminF.getText();
               Password = passF.getText();
          boolean ok = true;
          for (int i = 0; i < admins.size(); i++) {
          if (Admin.equals(admins.get(i).toString())) {
          if (Password.equals(passwords.get(i).toString())) {
          ok = true;
          this.setVisible(false);
          //break;
                         JOptionPane.showMessageDialog(null, "Welcome, u have successfully logged in");
                         mainpage();
          else {
          ok = false;
          else {
          ok = false;
          if (ok == false) {
                         JOptionPane.showMessageDialog(null,
                    "Incorrect Password or Admin No, Please Try Again",
                    "Access Denied",
                    JOptionPane.ERROR_MESSAGE);
          else {
          this.setVisible(false);
}

Answer 1

Hi, sorry to bring this thread up again, but this is actually a continuation from my previous posted program. Hope u guys can help me again!
Right now i'm supposed to come up with a simple quiz program, which consists of the center panel displayin the question (in a pic format), and a textfield to enter the answer at the lower panel. this goes on for a couple of pages and once it is completed, the final page would display the total correct answers out of the number of questions, as well as the score in percentage form.
The few(or many) problems taht i'm facing are :
1)How do i save the answers that are typed in each textfieldAnd later on checked for the correct answer based on the array given?
2)How do i go about doing the final score in percentage form and total of correct answers?
3)I previously tried out using canvas, but it didnt seem to work. my questions(pictures) that are supposed to displayed in the center(canvas) produce nothing. How do i rectify that?
i'm really sorry for the mess in the codings, hope this wouldnt be a hassle for any of u out there. Once again thanks in advance!
import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.io.*;
import java.net.URL;
import java.net.*;
import java.util.Vector;
import javax.swing.*;
import java.awt.image.*;
import java.lang.*;
import java.awt.Graphics;
public class eg31662 extends Applet implements ActionListener
    Panel panel1, panel2, panel3, panel4, panel5;
    Button login, enter;
    Label inst, top, admin, pass, startLabel;
    TextField adminF, passF, field;
    String Admin, Password;
    Vector admins, passwords;
     //Quiz declarations
     TextField ansF1,ansF2,ansF3;
     Button startBut, next0, next1, finishB, previous1;
     Image q1, q2, q3;
     Image ques[] = new Image[2];
     boolean text = false;
     boolean checked = false;
     int correct = 0;
     String [] answer = new String [2];
     String [] solution = {"11", "22", "33"};
     boolean text = false;
     boolean sound = true;
     int red,green,blue;
     int question =0;
     int good = 0;
     boolean pause= false;
     boolean start = true;*/
    Thread thread = null;
    boolean status = false;
    public void init()
        validateUser();
        setLayout (new BorderLayout());
        panel1 = new Panel(new FlowLayout());
        panel2 = new Panel(new FlowLayout());
        panel3 = new Panel(new FlowLayout());
        //login button
        login = new Button("Login");
        //instruction
        inst = new Label("Please type in your UserName and the given " +
                         "password in order to proceed");
        //label
        top = new Label("Top Label");
        admin = new Label("User Name :");
        pass = new Label("Password :");
        //input textfields
        adminF = new TextField(8);
        passF = new TextField(10);
        passF.setEchoChar('*');
        panel1.setBackground(Color.gray);
        panel2.setBackground(Color.orange);
          panel3.setBackground(Color.gray);
        panel2.add(admin);
        panel2.add(adminF);
        panel2.add(pass);
        panel2.add(passF);
        panel2.add(login);
        panel3.add(inst);
        panel1.add(top);
        add(panel1, BorderLayout.NORTH);
        add(panel2, BorderLayout.CENTER);
        add(panel3, BorderLayout.SOUTH);
        login.addActionListener(this);
        setSize(500,400);
    private void validateUser()
        String[] adminData    = {"t", "User1", "User2", "User3"};
        String[] passwordData = {"t", "P1", "P2", "P3"};
        admins = new Vector();
        passwords = new Vector();
        for(int j = 0; j < adminData.length; j++)
            admins.add(adminData[j]);
            passwords.add(passwordData[j]);
    private void Mainpage()
        boolean flag = true;
        removeAll();  // remove all components from container
        panel1 = new Panel(new FlowLayout());
        panel2 = new Panel(new FlowLayout());
          panel3 = new Panel(new FlowLayout());
        top = new Label("Welcome");
        enter = new Button("Enter");
        panel2.setBackground(Color.orange);
        panel1.setBackground(Color.gray);
        panel3.setBackground(Color.gray);
        startLabel = new Label("Welcome! " +
                                      "Please click on the 'Start' button to begin the quiz ");
          startBut = new Button("Start");
          startBut.requestFocus();
          Dimension dim = getSize();
          startBut.setSize(50,20);
        add(panel1, BorderLayout.NORTH);
        add(panel2, BorderLayout.CENTER);
        add(panel3, BorderLayout.SOUTH);
        panel2.add(startLabel);
        panel2.add(startBut);
        startBut.addActionListener(this);
        validate();
        repaint();
    private void Quiz1()
          //quizCanvas = new Canvas();
        boolean flag = true;
        removeAll();  // remove all components from container
        panel1 = new Panel(new FlowLayout());
        panel2 = new Panel(new FlowLayout());
        panel3 = new Panel(new FlowLayout());
        panel1.setBackground(Color.gray);
        panel2.setBackground(Color.orange);
        panel3.setBackground(Color.gray);
        add(panel1, BorderLayout.NORTH);
        add(panel2, BorderLayout.CENTER);
        add(panel3, BorderLayout.SOUTH);
          q1 = getImage(getDocumentBase(), "1.gif");
          ques[0] = q1;
          //ques[1] = q2;
          //previous = new Button("<");
          next0 = new Button("Done");
        ansF1 = new TextField(25);
          next0.addActionListener(this);
          //quizCanvas.insert(ques1);
        //panel3.add(previous);
        panel3.add(next0);
        panel3.add(ansF1);
        //panel2.add("1.gif");
          ansF1.requestFocus();
          ansF1.setText("focussing");
        validate();
        repaint();
     public void Quiz2(){
        boolean flag = true;
        removeAll();  // remove all components from container
        panel1 = new Panel(new FlowLayout());
        panel2 = new Panel(new FlowLayout());
        panel3 = new Panel(new FlowLayout());
        panel1.setBackground(Color.gray);
        panel2.setBackground(Color.orange);
        panel3.setBackground(Color.gray);
        add(panel1, BorderLayout.NORTH);
        add(panel2, BorderLayout.CENTER);
        add(panel3, BorderLayout.SOUTH);
          q2 = getImage(getDocumentBase(), "2.gif");
          ques[1] = q2;
          next1 = new Button("Done");
        ansF2 = new TextField(25);
          next1.addActionListener(this);
        panel3.add(next1);
        panel3.add(ansF2);
          ansF2.requestFocus();
          ansF2.setText("focussing");
        validate();
        repaint();
     public void Quiz3(){
        boolean flag = true;
        removeAll();  // remove all components from container
        panel1 = new Panel(new FlowLayout());
        panel2 = new Panel(new FlowLayout());
        panel3 = new Panel(new FlowLayout());
        panel1.setBackground(Color.gray);
        panel2.setBackground(Color.orange);
        panel3.setBackground(Color.gray);
        add(panel1, BorderLayout.NORTH);
        add(panel2, BorderLayout.CENTER);
        add(panel3, BorderLayout.SOUTH);
          q3 = getImage(getDocumentBase(), "3.gif");
          ques[2] = q3;
          finishB = new Button("Finish");
        ansF3 = new TextField(25);
          finishB.addActionListener(this);
        panel3.add(finishB);
        panel3.add(ansF3);
          ansF3.requestFocus();
          ansF3.setText("focussing");
        validate();
        repaint();
    public void start() {
        if(thread == null) {
            status = true;
    public void stop() {
        status = false;
    public void actionPerformed(ActionEvent ev)
        boolean ok = true;
        if(ev.getSource() == login)
            Admin = adminF.getText();
            Password = passF.getText();
            for (int i = 0; i < admins.size(); i++) {
                if (Admin.equals(admins.get(i).toString())) {
                    if (Password.equals(passwords.get(i).toString())) {
                        ok = true;
                        JOptionPane.showMessageDialog(null,
                                    "Welcome, u have successfully logged in");
                        Mainpage();
                        break;
                    else {
                        ok = false;
                else {
                    ok = false;
            if (!ok) {
                JOptionPane.showMessageDialog(null,
                              "Incorrect Password or Admin No, Please Try Again",
                              "Access Denied",
                               JOptionPane.ERROR_MESSAGE);
        if(ev.getSource() == startBut)
               Quiz1();
          if (ev.getSource () == next0) {
               saveanswer();
               Quiz2();
          if (ev.getSource () == next1) {
               //saveanswer();
               Quiz3();
          if (ev.getSource () == finishB) {
               //saveanswer();
               //checkanswer();
     /*class quizCanvas extends Canvas {
          private Image quest;
          public quizCanvas() {
               this.quest = null;
          public quizCanvas(Image quest) {
               this.quest = quest;
          public void insert(Image quest) {
               this.quest=quest;
               repaint();
          public void paint(Graphics g) {
     public void checkanswer() {
          if (!checked) {
          /*question = 0;
               for (int a=1;a<16;a++) {
                    question++;*/
                    if (ansF1) {
                         if (answer[1].toUpperCase().equals(solution[1])) {
                              correct++;
                    if (ansF2) {
                         if (answer[2].toUpperCase().equals(solution[2])) {
                              correct++;
                    if (ansF3) {
                         if (answer[3].toUpperCase().equals(solution[3])) {
                              correct++;
          checked = true;     }
     public void saveanswer() {
          if (text) {
               if (!ansF1.getText().equals("")) {
                    answer [Quiz1] = ansF1.getText();
               //answer2[question] = tf2.getText();
               if (!ansF2.getText().equals("")) {
                    answer [] = ansF2.getText();
               if (!ansF3.getText().equals("")) {
                    answer [] = ansF3.getText();
}