我一直在尝试通过使用按钮来删除SQLite中表中的数据。我已经能够使其在另一堂课上工作，但是我似乎无法使其在这一特定课上工作，我将向您展示。
该按钮称为btnDelete，而加载和删除数据库的方法称为delete_account。
Button btnDelete = new JButton("Delete Account");
btnDelete.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
delete_account();
}
});
public void delete_account(){
try { //start or try
//1)create a connection variable
Connection con;
//2)create an instance of the database class
Database db=new Database();
//3)pass the connection from DB to con
con=db.open_connection();
//4)create a statement variable to prepare the SQL
Statement statement=con.createStatement();
//5)create a query to insert the records
String query="DELETE FROM tblUsers WHERE userID="+ userid +"";
//6) execute the SQL code
if(statement.executeUpdate(query)==1) { //query was successful
JOptionPane.showMessageDialog(null, "Account successfully deleted!");
//clear the inputs
new MainInterface(user);
frmAccountSett.dispose();
}
}//end of try
catch (Exception e){//start of catch
//display the error
JOptionPane.showMessageDialog(null,e.getMessage());
}//end of catch
}//end of save_recipe()
这是该类中的所有代码，以防万一：
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JTextField;
import javax.swing.JPasswordField;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.sql.*;
public class AccSettings {
private JFrame frmAccountSett;
private JTextField txtFullname;
private JTextField txtUsername;
private JPasswordField txtPassword;
private int userid;
private String user;
/**
* Create the application.
*/
public AccSettings(String username) {
user=username;
//userid = id;
initialize();
edit_account();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frmAccountSett = new JFrame();
frmAccountSett.setTitle("Account Settings");
frmAccountSett.setBounds(100, 100, 450, 300);
frmAccountSett.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frmAccountSett.getContentPane().setLayout(null);
JLabel lblUsername = new JLabel("Edit Username:");
lblUsername.setBounds(85, 62, 103, 14);
frmAccountSett.getContentPane().add(lblUsername);
txtUsername = new JTextField();
txtUsername.setBounds(229, 59, 137, 20);
frmAccountSett.getContentPane().add(txtUsername);
txtUsername.setColumns(10);
txtPassword = new JPasswordField();
txtPassword.setBounds(229, 90, 137, 20);
frmAccountSett.getContentPane().add(txtPassword);
JButton btnConfirm = new JButton("Confirm Changes");
btnConfirm.setBounds(146, 164, 137, 29);
frmAccountSett.getContentPane().add(btnConfirm);
JLabel lblPassword = new JLabel("Edit Password:");
lblPassword.setBounds(85, 93, 103, 14);
frmAccountSett.getContentPane().add(lblPassword);
frmAccountSett.setVisible(true);
JButton btnDelete = new JButton("Delete Account");
btnDelete.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
delete_account();
}
});
btnDelete.setBounds(299, 227, 125, 23);
frmAccountSett.getContentPane().add(btnDelete);
JButton btnBack = new JButton("<< Back");
btnBack.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
frmAccountSett.dispose();
}
});
btnBack.setBounds(10, 227, 103, 23);
frmAccountSett.getContentPane().add(btnBack);
JLabel lblFullname = new JLabel("Edit Fullname:");
lblFullname.setBounds(85, 31, 103, 14);
frmAccountSett.getContentPane().add(lblFullname);
txtFullname = new JTextField();
txtFullname.setColumns(10);
txtFullname.setBounds(229, 28, 137, 20);
frmAccountSett.getContentPane().add(txtFullname);
btnConfirm.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent arg0) {
// TODO Auto-generated method stub
update_account();
}
});
}
public void delete_account(){
try { //start or try
//1)create a connection variable
Connection con;
//2)create an instance of the database class
Database db=new Database();
//3)pass the connection from DB to con
con=db.open_connection();
//4)create a statement variable to prepare the SQL
Statement statement=con.createStatement();
//5)create a query to insert the records
String query="DELETE FROM tblUsers WHERE userID="+ userid +"";
//6) execute the SQL code
if(statement.executeUpdate(query)==1) { //query was successful
JOptionPane.showMessageDialog(null, "Account successfully deleted!");
//clear the inputs
new MainInterface(user);
frmAccountSett.dispose();
}
}//end of try
catch (Exception e){//start of catch
//display the error
JOptionPane.showMessageDialog(null,e.getMessage());
}//end of catch
}//end of save_recipe()
public void update_account(){
try { //start or try
//1)create a connection variable
Connection con;
//2)create an instance of the database class
Database db=new Database();
//3)pass the connection from DB to con
con=db.open_connection();
//4)create a statement variable to prepare the SQL
Statement statement=con.createStatement();
//5)create a query to insert the records
@SuppressWarnings("deprecation")
String query="UPDATE tblUsers SET fullname='" + txtFullname.getText()+"',"
+ "username='" + txtUsername.getText()+"',"
+ "password='" + txtPassword.getText()+"'"
+ "WHERE userID="+ userid +"";
//6) execute the SQL code
if(statement.executeUpdate(query)==1) { //query was successful
JOptionPane.showMessageDialog(null, "Reference successfully updated!");
//clear the inputs
new MainInterface(user);
frmAccountSett.dispose();
}
}//end of try
catch (Exception e){//start of catch
//display the error
JOptionPane.showMessageDialog(null,e.getMessage());
}//end of catch
}//end of save_recipe()
//load the results
public void edit_account()
{
try {
Connection con; //create a variable for con
Database db = new Database(); //create an instance of database class
con = db.open_connection(); //set con as connection form database class
Statement st;
st = con.createStatement();
//create a statement variable
//create the query that will search the table based on similar terms
String query = "SELECT * FROM tblUsers WHERE userID=" + userid+ "";
//get the resultset of the query (rows)
ResultSet rs = st.executeQuery(query);
if (rs.next())
{
do{
txtFullname.setText(rs.getString(2));
txtUsername.setText(rs.getString(3));
txtPassword.setText(rs.getString(4));
}
while(rs.next());
}
/*
else {
JOptionPane.showMessageDialog(null, "Edit failed");
}
*/
}
catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
我认为问题主要来自zephyr所说的userID。我遵循了另一个类（frmEditRef）的代码，但是该类使用了JScrollPane，当从另一个类（frmMainInterface）调用它时，它看起来像这样：
public void mouseClicked(MouseEvent e) {
// TODO Auto-generated method stub
int x = table.getSelectedRow(); //get the current row
int ans = JOptionPane.showConfirmDialog(null, "Do you want to edit this record?");
if (ans == 0) {
//proceed to edit the transaction
//get the id
String id = String.valueOf(model.getValueAt(x, 0));
new EditRef(user,Integer.valueOf(id));
frmUserRef.dispose();
}
}
});
我尝试使用的类不使用JScrollPane。因此，其编码将有所不同。从frmMainInterface看起来是这样的：
btnAccountSett.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent arg0) {
// TODO Auto-generated method stub
String id = ;
new AccSettings(user,Integer.valueOf(id));
}
});
如您所见，我不知道在“ String id =”之后输入什么。
我希望这种解释能通过你们。我自己很难解释我什至不完全理解的东西。