AWTボタンを使用して「テキストフィールド」内の各データベースレコードをナビゲートして表示する方法は?
「次へ」ボタンが押されると、後続の各ヒットが次のデータベースレコードをそれぞれのテキストフィールドにフェッチするように、データベースレコードをナビゲートする Java フォームを作成しようとしています。このコードの問題は、[次へ] ボタンを何度押しても、テキスト フィールドに最初のレコードしか表示されないことです。
if(rs.next())そのような場合、条件が機能しないといういくつかのスレッドを読みました。これに対する適切な修正は何ですか?またその理由は何ですか?
PS: と 内の問題のある領域をマークしましProblem code beginsたProblem code ends。
import java.awt.Button;
import java.awt.Choice;
import java.awt.Frame;
import java.awt.GridLayout;
import java.awt.Label;
import java.awt.TextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import javax.swing.JOptionPane;
public class ManageEmployees implements ActionListener
{
Connection con;
Statement st;
ResultSet rs;
Frame f;
Choice employeeID;
Button savenewemployeeButton, updateemployeeButton, returndashboardButton, nextButton/*, previousButton, lastButton, firstButton*/;
Label nameLabel, usernameLabel, addressLabel, contactnumberLabel, passwordLabel, confirmpasswordLabel, selectemployeeLabel;
TextField nameTextField, usernameTextField, addressTextField, passwordTextField, confirmpasswordTextField;
ManageEmployees()
{
dbconnect();
initframe();
}
public void dbconnect()
{
try{
Class.forName("com.mysql.jdbc.Driver");
con=DriverManager.getConnection("jdbc:mysql://localhost:8889/InventoryManagement","root","root");
st=con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_UPDATABLE);
String sql="select * from SalesMen";
rs=st.executeQuery(sql);
}
catch(Exception ce)
{
ce.printStackTrace();
}
}
public void initframe()
{
f=new Frame("Manage Employees");
selectemployeeLabel=new Label("Select Employee Type:");
nameLabel=new Label("Employee Name:");
addressLabel=new Label("Address:");
usernameLabel=new Label("User Name:");
passwordLabel=new Label("Password:");
confirmpasswordLabel=new Label("Confirm Password:");
employeeID=new Choice();
employeeID.add("Sales Person");
employeeID.add("Sales Manager");
employeeID.add("Inventory Manager");
employeeID.add("Administrator");
savenewemployeeButton=new Button("Save New Employee details");
savenewemployeeButton.addActionListener(this);
returndashboardButton=new Button("Return to Dashboard");
returndashboardButton.addActionListener(this);
nextButton=new Button("Next");
nextButton.addActionListener(this);
nameTextField=new TextField(30);
addressTextField=new TextField(50);
usernameTextField=new TextField(20);
passwordTextField=new TextField(15);
confirmpasswordTextField=new TextField(15);
f.setLayout(new GridLayout(10,2,0,2));
f.add(selectemployeeLabel);
f.add(employeeID);
f.add(nameLabel);
f.add(nameTextField);
f.add(addressLabel);
f.add(addressTextField);
f.add(usernameLabel);
f.add(usernameTextField);
f.add(passwordLabel);
f.add(passwordTextField);
f.add(confirmpasswordLabel);
f.add(confirmpasswordTextField);
f.add(returndashboardButton);
f.add(savenewemployeeButton);
f.add(nextButton);
passwordTextField.setEchoChar('*');
confirmpasswordTextField.setEchoChar('*');
f.setSize(500,400);
f.setVisible(true);
f.setResizable(false);
f.addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent we)
{
System.exit(0);
}
}
);
}
public void actionPerformed(ActionEvent e)
{
// Return to dashboard on button click
if(e.getSource()==returndashboardButton)
{
f.dispose();
new Dashboard();
}
// ---------------------------------------- (Begin) Save new employee information ------------------------------------------------------------//
// Save new Sales Person information
String salesmen=employeeID.getSelectedItem();
if(salesmen=="Sales Person" && e.getSource()==savenewemployeeButton)
{
try
{
String fullname1=nameTextField.getText();
String address1=usernameTextField.getText();
String username1=addressTextField.getText();
String password1=passwordTextField.getText();
String sql="insert into SalesMen values('"+fullname1+"','"+address1+"','"+username1+"','"+password1+"')";
st.executeUpdate(sql);
JOptionPane.showMessageDialog(null,"New Sales Man's details saved!");
}
catch(Exception ce)
{
ce.printStackTrace();
}
}
// Save new Sales Manager information
String salesmanager=employeeID.getSelectedItem();
if(salesmanager=="Sales Manager" && e.getSource()==savenewemployeeButton)
{
try
{
String fullname1=nameTextField.getText();
String address1=usernameTextField.getText();
String username1=addressTextField.getText();
String password1=passwordTextField.getText();
String sql="insert into SalesManagers values('"+fullname1+"','"+address1+"','"+username1+"','"+password1+"')";
st.executeUpdate(sql);
JOptionPane.showMessageDialog(null,"New Sales Manager's details saved!");
}
catch(Exception ce)
{
ce.printStackTrace();
}
}
// Save new Inventory Manger information
String inventorymanger=employeeID.getSelectedItem();
if(inventorymanger=="Inventory Manager" && e.getSource()==savenewemployeeButton)
{
try
{
String fullname1=nameTextField.getText();
String address1=usernameTextField.getText();
String username1=addressTextField.getText();
String password1=passwordTextField.getText();
String sql="insert into InventoryManagers values('"+fullname1+"','"+address1+"','"+username1+"','"+password1+"')";
st.executeUpdate(sql);
JOptionPane.showMessageDialog(null,"New Inventory Manager's details saved!");
}
catch(Exception ce)
{
ce.printStackTrace();
}
}
// Save new Administrator information
String administrator=employeeID.getSelectedItem();
if(administrator=="Administrator" && e.getSource()==savenewemployeeButton)
{
try
{
String fullname1=nameTextField.getText();
String address1=usernameTextField.getText();
String username1=addressTextField.getText();
String password1=passwordTextField.getText();
String sql="insert into Administrators values('"+fullname1+"','"+address1+"','"+username1+"','"+password1+"')";
st.executeUpdate(sql);
JOptionPane.showMessageDialog(null,"New Admin's details saved!");
}
catch(Exception ce)
{
ce.printStackTrace();
}
// ---------------------------------------- (End) Save new employee information ------------------------------------------------------------//
}
if(salesmen=="Sales Person" && e.getSource()==nextButton)
{
try
{
String sql="select * from SalesMen";
rs=st.executeQuery(sql);
// Problem code begins
if(rs.next())
{
nameTextField.setText(rs.getString("FullName"));
usernameTextField.setText(rs.getString("UserName"));
addressTextField.setText(rs.getString("Address"));
}
else
{
rs.previous();
System.out.println("boo!");
JOptionPane.showMessageDialog(null,"No more records");
}
}
// Problem code ends
catch(Exception ce)
{
ce.printStackTrace();
}
}
}
public static void main(String[] args)
{
new ManageEmployees();
}
}