Problem with action listener

Question

hello
the problem in my code is that i defined
actionlistener for a button but it does not
do what it should do . it throws an error in the console
and i think my code is 100% correct what is the problem
please help me this is the codewith
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
class Library extends JFrame implements ActionListener     {
     private JMenuBar jmb      = new JMenuBar();
     private JMenu books      = new JMenu("Books",true);
     private JMenu members      = new JMenu("Members",true);
     private JMenu loans      = new JMenu("Loans",true);
     private JMenuItem addNb = new JMenuItem("Add New Book");
     private JMenuItem listB = new JMenuItem("List All Books");
     private JMenuItem listAb = new JMenuItem("List Available Books");
     private JMenuItem listBb = new JMenuItem("List Borrowed Books");
     private JMenuItem addNm = new JMenuItem("Add New Member");
     private JMenuItem removeM = new JMenuItem("Remove a Member");
     private JMenuItem listAm = new JMenuItem("List All Members");
     private JMenuItem loanB = new JMenuItem("Loan A Book");
     private JMenuItem returnB = new JMenuItem("Return A Book");
     private JTextField bNumber = new JTextField(14);
     private JTextField bAuthor = new JTextField(14);
     private JTextField bTitle = new JTextField(14);
     private JTextField mId = new JTextField(14);
     private JTextField mName = new JTextField(14);
     private JTextField idB = new JTextField(14);
     private JTextField nBToB = new JTextField(14);
     private JTextField nBTor = new JTextField(14);
     private JTextArea dispaly = new JTextArea();
     private JButton oKb1 = new JButton("OK");
     private JButton okb2 = new JButton("OK");
     private JButton cloaseb = new JButton("Close");
     private JButton oKm1 = new JButton("OK");
     private JButton oKm2 = new JButton("OK");
     private JButton cancelM = new JButton("Cancel");
     private JButton oKm3 = new JButton("OK");
     private JButton oKm4 = new JButton("OK");
     private JButton cancelM2 = new JButton("Cancel");
     private JButton oKl = new JButton("OK");
     private JButton oKr = new JButton("OK");
     private JButton yes = new JButton("Yes");
     private JButton no = new JButton("No");     
     private JLabel bN = new JLabel("Book Number");
     private JLabel bA = new JLabel("Book Author");
     private JLabel bT = new JLabel("Book Title");
     private JLabel iN          = new JLabel("ID Number");
     private JLabel mN          = new JLabel("Member's Name");
     private JLabel     iNb          = new JLabel("ID number of the borrower");
     private JLabel nBb          = new JLabel("Number of the books to borrow");
     private JLabel nBr          = new JLabel("Number of the books to return");
     private JLabel mIdl     = new JLabel("ID number of the stuednt");
     private JPanel tempoIPanel= new JPanel(new FlowLayout());
     Container cp;
     JFrame mainFrame;
     JInternalFrame tempoI;
Library()     {
     //LibraryClass lClass = new LibraryClass();/*
     mainFrame = new JFrame();
     mainFrame.setJMenuBar(jmb);
     mainFrame.setSize(800,550);
     mainFrame.getContentPane().setLayout(new FlowLayout());
     jmb.add(books);
     jmb.add(members);
     jmb.add(loans);
     books.add(addNb);
     addNb.addActionListener(this);
     books.add(listB);
     listB.addActionListener(this);
     books.add(listAb);
     listAb.addActionListener(this);
     books.add(listBb);
     listBb.addActionListener(this);
     members.add(addNm);
     addNm.addActionListener(this);
     members.add(removeM);
     removeM.addActionListener(this);
     members.add(listAm);
     listAm.addActionListener(this);
     loans.add(loanB);
     loanB.addActionListener(this);
     loans.add(returnB);
     returnB.addActionListener(this);
     //actions listeners
     oKb1.addActionListener(this);
     mainFrame.setVisible(true);
public void actionPerformed(ActionEvent ae)     {
     if(ae.getSource() == addNb)     {
          tempoI = new JInternalFrame("Add new Book",true,true);
          mainFrame.getContentPane().add(tempoI);
          tempoI.getContentPane().setLayout(new FlowLayout());
          tempoI.getContentPane().add(bN);
          tempoI.getContentPane().add(bNumber);
          tempoI.getContentPane().add(bA);
          tempoI.getContentPane().add(bAuthor);
          tempoI.getContentPane().add(bT);
          tempoI.getContentPane().add(bTitle);
          tempoI.getContentPane().add(oKb1);//add action listener here
          tempoI.setVisible(true);
     if(ae.getSource() == listB)     {
          //LibraryClass.listBooks();
     if(ae.getSource() == listAb){}
     if(ae.getSource() == listBb){}
     if(ae.getSource() == addNm)     {
          tempoI = new JInternalFrame("Add new Member",true,true);
          mainFrame.getContentPane().add(tempoI);
          tempoI.getContentPane().setLayout(new FlowLayout());
          tempoI.getContentPane().add(iN);
          tempoI.getContentPane().add(mId);
          tempoI.getContentPane().add(mN);
          tempoI.getContentPane().add(mName);
          tempoI.getContentPane().add(oKm1);//add action listener
          tempoI.getContentPane().setSize(300,400);
          tempoI.setVisible(true);
     if(ae.getSource() == removeM)     {
          tempoI = new JInternalFrame("Rmove member",true,true);
          mainFrame.getContentPane().add(tempoI);
          tempoI.getContentPane().setLayout(new FlowLayout());
          tempoI.getContentPane().add(mIdl);
          tempoI.getContentPane().add(mId);
          tempoI.getContentPane().add(oKm2);//add action listener
          //LibraryClass.removeM(Double.parseDouble(mId.getText()));
          tempoI.getContentPane().setSize(300,400);
          tempoI.setVisible(true);
     if(ae.getSource() == listAm)     {
          //LibraryClass.listMembers();
     if(ae.getSource() == loanB)     {
          tempoI = new JInternalFrame("Loan book",true,true);
          mainFrame.getContentPane().add(tempoI);
          tempoI.getContentPane().setLayout(new FlowLayout());
          tempoI.getContentPane().add(iNb);
          tempoI.getContentPane().add(idB);
          tempoI.getContentPane().add(nBb);
          tempoI.getContentPane().add(nBToB);
          tempoI.getContentPane().add(oKl);
          //LibraryClass.borrowBook(Book bk,Member m);
          tempoI.getContentPane().setSize(300,400);
          tempoI.setVisible(true);
     if(ae.getSource() == returnB)     {
          tempoI = new JInternalFrame("Return Book",true,true);
          mainFrame.getContentPane().add(tempoI);
          tempoI.getContentPane().setLayout(new FlowLayout());
          tempoI.getContentPane().add(iNb);
          tempoI.getContentPane().add(idB);
          tempoI.getContentPane().add(nBr);
          tempoI.getContentPane().add(nBTor);
          tempoI.getContentPane().add(oKr);
          tempoI.getContentPane().setSize(400,300);
          tempoI.setVisible(true);
          //Book.addBook(bNumber.getText(),bAuthor.getText(),bTitle.getText());
class ClubLibrarySystem     {
     public static void main(String[] args)     {
     new Library();
}

Answer 1

hello
the problem in my code is that i defined
actionlistener for a button but it does not
do what it should do . it throws an error in the
consoleWhat error?
and i think my code is 100% correct what is theWell, but it isn't.
Have you tried using a debugger?
problem
please help me this is the codewith
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
class Library extends JFrame implements
ActionListener     {
     private JMenuBar jmb      = new JMenuBar();
     private JMenu books      = new JMenu("Books",true);
private JMenu members      = new
JMenu("Members",true);
private JMenu loans      = new
JMenu("Loans",true);
private JMenuItem addNb = new JMenuItem("Add New
Book");
private JMenuItem listB = new JMenuItem("List All
Books");
private JMenuItem listAb = new JMenuItem("List
Available Books");
private JMenuItem listBb = new JMenuItem("List
Borrowed Books");
private JMenuItem addNm = new JMenuItem("Add New
Member");
private JMenuItem removeM = new JMenuItem("Remove a
Member");
private JMenuItem listAm = new JMenuItem("List All
Members");
private JMenuItem loanB = new JMenuItem("Loan A
Book");
private JMenuItem returnB = new JMenuItem("Return A
Book");
     private JTextField bNumber = new JTextField(14);
     private JTextField bAuthor = new JTextField(14);
     private JTextField bTitle = new JTextField(14);
     private JTextField mId = new JTextField(14);
     private JTextField mName = new JTextField(14);
     private JTextField idB = new JTextField(14);
     private JTextField nBToB = new JTextField(14);
     private JTextField nBTor = new JTextField(14);
     private JTextArea dispaly = new JTextArea();
     private JButton oKb1 = new JButton("OK");
     private JButton okb2 = new JButton("OK");
     private JButton cloaseb = new JButton("Close");
     private JButton oKm1 = new JButton("OK");
     private JButton oKm2 = new JButton("OK");
     private JButton cancelM = new JButton("Cancel");
     private JButton oKm3 = new JButton("OK");
     private JButton oKm4 = new JButton("OK");
     private JButton cancelM2 = new JButton("Cancel");
     private JButton oKl = new JButton("OK");
     private JButton oKr = new JButton("OK");
     private JButton yes = new JButton("Yes");
     private JButton no = new JButton("No");     
private JLabel bN = new JLabel("Book
Number");
private JLabel bA = new JLabel("Book
Author");
private JLabel bT = new JLabel("Book
Title");
     private JLabel iN          = new JLabel("ID Number");
private JLabel mN          = new JLabel("Member's
Name");
private JLabel     iNb          = new JLabel("ID number of the
borrower");
private JLabel nBb          = new JLabel("Number of the
books to borrow");
private JLabel nBr          = new JLabel("Number of the
books to return");
private JLabel mIdl     = new JLabel("ID number of
the stuednt");
private JPanel tempoIPanel= new JPanel(new
FlowLayout());
     Container cp;
     JFrame mainFrame;
     JInternalFrame tempoI;
Library()     {
     //LibraryClass lClass = new LibraryClass();/*
     mainFrame = new JFrame();
     mainFrame.setJMenuBar(jmb);
     mainFrame.setSize(800,550);
mainFrame.getContentPane().setLayout(new
FlowLayout());
     jmb.add(books);
     jmb.add(members);
     jmb.add(loans);
     books.add(addNb);
     addNb.addActionListener(this);
     books.add(listB);
     listB.addActionListener(this);
     books.add(listAb);
     listAb.addActionListener(this);
     books.add(listBb);
     listBb.addActionListener(this);
     members.add(addNm);
     addNm.addActionListener(this);
     members.add(removeM);
     removeM.addActionListener(this);
     members.add(listAm);
     listAm.addActionListener(this);
     loans.add(loanB);
     loanB.addActionListener(this);
     loans.add(returnB);
     returnB.addActionListener(this);
     //actions listeners
     oKb1.addActionListener(this);
     mainFrame.setVisible(true);
public void actionPerformed(ActionEvent ae)     {
     if(ae.getSource() == addNb)     {
tempoI = new JInternalFrame("Add new
w Book",true,true);
          mainFrame.getContentPane().add(tempoI);
tempoI.getContentPane().setLayout(new
w FlowLayout());
          tempoI.getContentPane().add(bN);
          tempoI.getContentPane().add(bNumber);
          tempoI.getContentPane().add(bA);
          tempoI.getContentPane().add(bAuthor);
          tempoI.getContentPane().add(bT);
          tempoI.getContentPane().add(bTitle);
tempoI.getContentPane().add(oKb1);//add action
n listener here
          tempoI.setVisible(true);
     if(ae.getSource() == listB)     {
          //LibraryClass.listBooks();
     if(ae.getSource() == listAb){}
     if(ae.getSource() == listBb){}
     if(ae.getSource() == addNm)     {
tempoI = new JInternalFrame("Add new
w Member",true,true);
          mainFrame.getContentPane().add(tempoI);
tempoI.getContentPane().setLayout(new
w FlowLayout());
          tempoI.getContentPane().add(iN);
          tempoI.getContentPane().add(mId);
          tempoI.getContentPane().add(mN);
          tempoI.getContentPane().add(mName);
tempoI.getContentPane().add(oKm1);//add action
n listener
          tempoI.getContentPane().setSize(300,400);
          tempoI.setVisible(true);
     if(ae.getSource() == removeM)     {
tempoI = new JInternalFrame("Rmove
e member",true,true);
          mainFrame.getContentPane().add(tempoI);
tempoI.getContentPane().setLayout(new
w FlowLayout());
          tempoI.getContentPane().add(mIdl);
          tempoI.getContentPane().add(mId);
tempoI.getContentPane().add(oKm2);//add action
n listener
          //LibraryClass.removeM(Double.parseDouble(mId.getText
          tempoI.getContentPane().setSize(300,400);
          tempoI.setVisible(true);
     if(ae.getSource() == listAm)     {
          //LibraryClass.listMembers();
     if(ae.getSource() == loanB)     {
          tempoI = new JInternalFrame("Loan book",true,true);
          mainFrame.getContentPane().add(tempoI);
tempoI.getContentPane().setLayout(new
w FlowLayout());
          tempoI.getContentPane().add(iNb);
          tempoI.getContentPane().add(idB);
          tempoI.getContentPane().add(nBb);
          tempoI.getContentPane().add(nBToB);
          tempoI.getContentPane().add(oKl);
          //LibraryClass.borrowBook(Book bk,Member m);
          tempoI.getContentPane().setSize(300,400);
          tempoI.setVisible(true);
     if(ae.getSource() == returnB)     {
tempoI = new JInternalFrame("Return
n Book",true,true);
          mainFrame.getContentPane().add(tempoI);
tempoI.getContentPane().setLayout(new
w FlowLayout());
          tempoI.getContentPane().add(iNb);
          tempoI.getContentPane().add(idB);
          tempoI.getContentPane().add(nBr);
          tempoI.getContentPane().add(nBTor);
          tempoI.getContentPane().add(oKr);
          tempoI.getContentPane().setSize(400,300);
          tempoI.setVisible(true);
          //Book.addBook(bNumber.getText(),bAuthor.getText(),bT
tle.getText());
class ClubLibrarySystem     {
     public static void main(String[] args)     {
     new Library();