Untitled

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;

public class assg1setC1 extends JFrame implements ActionListener {
    JTextField txtname, txtstd;
    JButton btnadd, btndelete, btnsearch;
    JPanel p1;
    Hashtable<String, String> table = new Hashtable<>();

    assg1setC1() {
        setTitle("City STD Code Information");
        setSize(700, 500);
        setVisible(true);
        setLayout(new GridLayout(3, 2, 20, 20));
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JLabel name = new JLabel("Enter City Name: ");
        add(name);
        txtname = new JTextField(10);
        add(txtname);

        JLabel stdcode = new JLabel("Enter STD Code: ");
        add(stdcode);
        txtstd = new JTextField(10);
        add(txtstd);

        JLabel op = new JLabel("Choose Operation: ");
        add(op);

        p1 = new JPanel();
        p1.setLayout(new GridLayout(1, 3, 5, 5));

        btnadd = new JButton("Add");
        p1.add(btnadd);
        btnadd.addActionListener(this);

        btndelete = new JButton("Delete");
        p1.add(btndelete);
        btndelete.addActionListener(this);

        btnsearch = new JButton("Search");
        p1.add(btnsearch);
        btnsearch.addActionListener(this);

        add(p1);

    }// SETC1

    public void actionPerformed(ActionEvent ae) {

        String name = (txtname.getText());
        String std = (txtstd.getText());

        if (ae.getSource() == btnadd) {

            // System.out.println(table.containsKey(name) || table.containsValue(std));
            if (table.containsKey(name) || table.containsValue(std)) {
                String s2 = "Duplicates are not allowded ";
                JOptionPane.showMessageDialog(null,s2,s2, JOptionPane.ERROR_MESSAGE);

            } else {
                table.put(name, std);
                System.out.println(table);
                JOptionPane.showMessageDialog(null, "Succesfully Added City & STD Code", name,
                        JOptionPane.INFORMATION_MESSAGE);
            }
            txtname.setText("");
            txtstd.setText("");

        }
        if (ae.getSource() == btndelete) {
            String s1 = JOptionPane.showInputDialog(null, "Enter City to remove");
            table.remove(s1);
            JOptionPane.showMessageDialog(null, "Succesfully removed City & STD Code", name,
                    JOptionPane.INFORMATION_MESSAGE);
        }

        if (ae.getSource() == btnsearch) {
            String s1 = JOptionPane.showInputDialog(null, "Enter City");

            if (table.containsKey(s1)) {
                String s2 = "STD Code: " + table.get(s1);
                JOptionPane.showMessageDialog(null, s2);
            } else {
                JOptionPane.showMessageDialog(null, "ERROR OCCURED");

            }

        }

    }

    public static void main(String[] args) {
        new assg1setC1();
    }
}