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

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On 11/29/2012 1:12 PM, Lew wrote:
> Knute Johnson wrote:
>>       public class Employee implements Comparable {
>>           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 int compareTo(Object emp) {
>>               return getName().compareTo(((Employee)emp).getName());
>>           }
>>
>>           public String toString() {
>>               return String.format("%s %d",getName(),getNumber());
>>           }
>>       }
>
> 'Employee' needs to override 'equals()' to be consistent with 'compareTo()'.

 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

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Thread

How to implement jcombobox with name value pair from database? rogerdoger777 <kedward777@gmail.com> - 2012-11-29 09:14 -0800
  Re: How to implement jcombobox with name value pair from database? kedward777@gmail.com - 2012-11-29 11:21 -0800
    Re: How to implement jcombobox with name value pair from database? Roedy Green <see_website@mindprod.com.invalid> - 2012-12-04 18:08 -0800
  Re: How to implement jcombobox with name value pair from database? Knute Johnson <nospam@knutejohnson.com> - 2012-11-29 12:55 -0800
    Re: How to implement jcombobox with name value pair from database? Lew <lewbloch@gmail.com> - 2012-11-29 13:12 -0800
      Re: How to implement jcombobox with name value pair from database? Knute Johnson <nospam@knutejohnson.com> - 2012-11-29 15:05 -0800
        Re: How to implement jcombobox with name value pair from database? Lew <lewbloch@gmail.com> - 2012-11-29 16:08 -0800
  Re: How to implement jcombobox with name value pair from database? kedward777@gmail.com - 2012-11-29 13:17 -0800

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