Re: How to implement jcombobox with name value pair from database?

On 11/29/2012 1:12 PM, Lew wrote:


 From what I can read in the docs Employee only needs to be "consistent
with equals" if it is to be used in a Set or as a key in SortedMap. I'm
not using Sets. Employees are values in the HashMap and so neither
compareTo() nor equals() would be called if the map were sorted.
Collections.sort() uses the compareTo() to accomplish the sort and
doesn't need equals() as far as I can tell.

So maybe it would have been better to create a Comparator instead of
making Employee Comparable. Employee would still need an equals()
method if it were to be used in a Set.

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

public class test extends JPanel {
     private final Vector<Employee> v = new Vector<>();
     private final Map<Integer,Employee> map = new HashMap<>();
     private final JComboBox<Employee> box;
     private final JTextField f;

     public test() {
         Employee bob = new Employee(12,"Bob");
         Employee jerry = new Employee(65,"Jerry");
         Employee jane = new Employee(70,"Jane");
         Employee sharon = new Employee(82,"Sharon");
         Employee anne = new Employee(23,"Anne");

         map.put(bob.getNumber(),bob);
         map.put(jerry.getNumber(),jerry);
         map.put(jane.getNumber(),jane);
         map.put(sharon.getNumber(),sharon);
         map.put(anne.getNumber(),anne);

         v.addAll(map.values());
         Collections.sort(v,new EmployeeNameComparator());

         box = new JComboBox<Employee>(v);
         add(box);

         f = new JTextField("",5);
         add(f);

         JButton b = new JButton("Find");
         b.addActionListener(new ActionListener() {
             public void actionPerformed(ActionEvent ae) {
                 boolean found = false;
                 try {
                     int number = Integer.parseInt(f.getText().trim());
                     Employee emp = map.get(number);
                     if (emp == null)
                         JOptionPane.showMessageDialog(test.this,
                          "Employee Doesn't Exist",
                          "Error!",
                          JOptionPane.ERROR_MESSAGE);
                     box.setSelectedItem(emp);
                 } catch (NumberFormatException nfe) {
                     JOptionPane.showMessageDialog(test.this,nfe);
                 }
             }
         });
         add(b);
     }

     public class Employee {
         private int number;
         private String name;

         public Employee(int number, String name) {
             this.number = number;
             this.name = name;
         }

         public String getName() {
             return name;
         }

         public int getNumber() {
             return number;
         }

         public String toString() {
             return String.format("%s %d",getName(),getNumber());
         }
     }

     public class EmployeeNameComparator implements Comparator<Employee> {
         public int compare(Employee emp1, Employee emp2) {
             return emp1.getName().compareTo(emp2.getName());
         }
     }

     public static void main(String[] args) {
         EventQueue.invokeLater(new Runnable() {
             public void run() {
                 JFrame f = new JFrame("test");
                 f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
                 test t = new test();
                 f.add(t,BorderLayout.CENTER);
                 f.pack();
                 f.setVisible(true);
             }
         });
     }
}

--

Knute Johnson