The Java Program below is similar to the topic I created about retrieving data from database and display using JList, the only difference is that this program is using JComboBox instead of JList to display the retrieved data from MS Access Database. See "Important Part of the Program" below to compare and understand the whole java program easily.
Download: retrieveDBUsingJCB.rar
Output:
/**
* File: retrieveDBUsingJCB.java
* Tiltle: Retrieve Data From Database and Display Using JComboBox
* Author: http://java-code-complete.blogspot.com/
*/
//Java Core Package
import javax.swing.*;
//Java Extension Package
import java.awt.*;
import java.awt.event.*;
import java.sql.*;
public class retrieveDBUsingJCB extends JFrame {
//Initializing program components
private JButton buttons[];
private JComboBox listBox;
private JPanel p1,p2;
private String bLabel[] = {"ID","First Name","Middle Name","Last Name","Age"};
Connection con;
Statement st;
ResultSet rs;
String db;
//Setting up GUI
public retrieveDBUsingJCB() {
//Setting up the Title of the Window
super("Retrieve DB and Display Using JComboBox");
//Set Size of the Window (WIDTH, HEIGHT)
setSize(300,200);
//Exit Property of the Window
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Constructing JButtons and JComboBox
buttons = new JButton[5];
listBox = new JComboBox();
//Setting up JComboBox property
listBox.setMaximumRowCount(5);
//Constructing JPanel 1 and its property
p1 = new JPanel();
p1.setBorder(BorderFactory.createTitledBorder("Database: "));
p1.add(listBox); //Adding JComboBox in JPanel 1
//Constructing JPanel 2 and its property
p2 = new JPanel();
p2.setLayout(new GridLayout(5,1));
p2.setBorder(BorderFactory.createTitledBorder("Display: "));
//Constructing all 5 JButtons using "for loop" and add it in JPanel 2
for(int count=0; count<buttons.length; count++) {
buttons[count] = new JButton(bLabel[count]);
p2.add(buttons[count]);
}
//Setting up the container ready for the components to be added.
Container pane = getContentPane();
setContentPane(pane);
//Setting up the container layout
GridLayout grid = new GridLayout(1,2);
pane.setLayout(grid);
//Creating a connection to MS Access and fetch errors using "try-catch" to check if it is successfully connected or not.
try {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
db = "jdbc:odbc:Driver={Microsoft Access Driver (*.mdb)};DBQ=addItemDB.mdb;";
con = DriverManager.getConnection(db,"","");
st = con.createStatement();
} catch (Exception e) {
JOptionPane.showMessageDialog(null,"Failed to Connect to Database","Error Connection", JOptionPane.WARNING_MESSAGE);
System.exit(0);
}
//Implemeting Even-Listener on JButton buttons[0] which is ID
buttons[0].addActionListener(
new ActionListener() {
//Handle JButton event if it is clicked
public void actionPerformed(ActionEvent event) {
try {
listBox.removeAllItems();
//SQL for selecting the table "person" in the Database
rs=st.executeQuery("select * from person");
while (rs.next()) {
//Displaying the field "id" from the table "person" in JComboBox
listBox.addItem(rs.getString("id"));
}
} catch (Exception e) {
System.out.println("Retrieving Data Fail");
}
}
}
);
//Implemeting Even-Listener on JButton buttons[1] which is First Name
buttons[1].addActionListener(
new ActionListener() {
//Handle JButton event if it is clicked
public void actionPerformed(ActionEvent event) {
try {
listBox.removeAllItems();
//SQL for selecting the table "person" in the Database
rs=st.executeQuery("select * from person");
while (rs.next()) {
//Displaying the field "firstName" from the table "person" in JComboBox
listBox.addItem(rs.getString("firstName"));
}
} catch (Exception e) {
System.out.println("Retrieving Data Fail");
}
}
}
);
//Implemeting Even-Listener on JButton buttons[2] which is Middle Name
buttons[2].addActionListener(
new ActionListener() {
//Handle JButton event if it is clicked
public void actionPerformed(ActionEvent event) {
try {
listBox.removeAllItems();
//SQL for selecting the table "person" in the Database
rs=st.executeQuery("select * from person");
while (rs.next()) {
//Displaying the field "middleName" from the table "person" in JComboBox
listBox.addItem(rs.getString("middleName"));
}
} catch (Exception e) {
System.out.println("Retrieving Data Fail");
}
}
}
);
//Implemeting Even-Listener on JButton buttons[3] which is Last Name
buttons[3].addActionListener(
new ActionListener() {
//Handle JButton event if it is clicked
public void actionPerformed(ActionEvent event) {
try {
listBox.removeAllItems();
//SQL for selecting the table "person" in the Database
rs=st.executeQuery("select * from person");
while (rs.next()) {
//Displaying the field "lastName" from the table "person" in JComboBox
listBox.addItem(rs.getString("familyName"));
}
} catch (Exception e) {
System.out.println("Retrieving Data Fail");
}
}
}
);
//Implemeting Even-Listener on JButton buttons[4] which is Age
buttons[4].addActionListener(
new ActionListener() {
//Handle JButton event if it is clicked
public void actionPerformed(ActionEvent event) {
try {
listBox.removeAllItems();
//SQL for selecting the table "person" in the Database
rs=st.executeQuery("select * from person");
while (rs.next()) {
//Displaying the field "age" from the table "person" in JComboBox
listBox.addItem(rs.getString("age"));
}
} catch (Exception e) {
System.out.println("Retrieving Data Fail");
}
}
}
);
//Adding components to the container
pane.add(p1);
pane.add(p2);
/**Set all the Components Visible.
* If it is set to "false", the components in the container will not be visible.
*/
setVisible(true);
setResizable(false);
}
//Main Method
public static void main (String[] args) {
retrieveDBUsingJCB rdjcb = new retrieveDBUsingJCB();
}
}
Important Part of the Program:
//Implemeting Even-Listener on JButton buttons[0] which is ID
buttons[0].addActionListener(
new ActionListener() {
//Handle JButton event if it is clicked
public void actionPerformed(ActionEvent event) {
try {
listBox.removeAllItems();
//SQL for selecting the table "person" in the Database
rs=st.executeQuery("select * from person");
while (rs.next()) {
//Displaying the field "id" from the table "person" in JComboBox
listBox.addItem(rs.getString("id"));
}
} catch (Exception e) {
System.out.println("Retrieving Data Fail");
}
}
}
);
//Implemeting Even-Listener on JButton buttons[1] which is First Name
buttons[1].addActionListener(
new ActionListener() {
//Handle JButton event if it is clicked
public void actionPerformed(ActionEvent event) {
try {
listBox.removeAllItems();
//SQL for selecting the table "person" in the Database
rs=st.executeQuery("select * from person");
while (rs.next()) {
//Displaying the field "firstName" from the table "person" in JComboBox
listBox.addItem(rs.getString("firstName"));
}
} catch (Exception e) {
System.out.println("Retrieving Data Fail");
}
}
}
);
//Implemeting Even-Listener on JButton buttons[2] which is Middle Name
buttons[2].addActionListener(
new ActionListener() {
//Handle JButton event if it is clicked
public void actionPerformed(ActionEvent event) {
try {
listBox.removeAllItems();
//SQL for selecting the table "person" in the Database
rs=st.executeQuery("select * from person");
while (rs.next()) {
//Displaying the field "middleName" from the table "person" in JComboBox
listBox.addItem(rs.getString("middleName"));
}
} catch (Exception e) {
System.out.println("Retrieving Data Fail");
}
}
}
);
//Implemeting Even-Listener on JButton buttons[3] which is Last Name
buttons[3].addActionListener(
new ActionListener() {
//Handle JButton event if it is clicked
public void actionPerformed(ActionEvent event) {
try {
listBox.removeAllItems();
//SQL for selecting the table "person" in the Database
rs=st.executeQuery("select * from person");
while (rs.next()) {
//Displaying the field "lastName" from the table "person" in JComboBox
listBox.addItem(rs.getString("familyName"));
}
} catch (Exception e) {
System.out.println("Retrieving Data Fail");
}
}
}
);
//Implemeting Even-Listener on JButton buttons[4] which is Age
buttons[4].addActionListener(
new ActionListener() {
//Handle JButton event if it is clicked
public void actionPerformed(ActionEvent event) {
try {
listBox.removeAllItems();
//SQL for selecting the table "person" in the Database
rs=st.executeQuery("select * from person");
while (rs.next()) {
//Displaying the field "age" from the table "person" in JComboBox
listBox.addItem(rs.getString("age"));
}
} catch (Exception e) {
System.out.println("Retrieving Data Fail");
}
}
}
);
