问题
got a problem here, trying to create a login to database system at the moment. I have to classes : UserLogManagerMainWindow and DatabaseConnectionFrame. My program is about log management. I want to make a database connection :
UserLogManagerMainWindow class has a button "Connect to database", on it's click DatabaseConnectionFrame initialize and gets up a frame with jlabels and jtextfields, after I enter everything i need, i press "Login" button, after this I want that my UserLogManagerMainWindow class continues on pressenting the logs from connected database.
I have written some code about how it supposed to look : "the logic about what am i trying to say"
connectToDatabaseBtn.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
DatabaseConnectionFrame dcf = new DatabaseConnectionFrame();
dcf.setVisible(true);
if(dcf.answer == true) {
importButtons(menuBar);
setJMenuBar(menuBar);
try {
DatabaseComm.getColumnNamesToPanel(model, titles);
projects = DatabaseComm.AddLogsToArrayReturnProjectNames(events);
DatabaseComm.fillDataToPanel(model, events, titles, row);
DatabaseComm.resizeColumnWidth(table);
} catch (SQLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
else {
System.out.println("not working");
}
}
});
But if statement does not working, i know why. That's why i'm asking how to make it work? More likely, threading is the key, but not good at it at the moment. Any tips without threading? And if threading is the only way, may i get some help of it?
Giving DatabaseConnectionFrame class below either:
package manager;
import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import java.awt.GridBagLayout;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import java.awt.GridBagConstraints;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.net.InetAddress;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import javax.swing.JTextField;
import javax.swing.JPasswordField;
import javax.swing.SwingConstants;
import javax.swing.JButton;
public class DatabaseConnectionFrame extends JFrame{
private JPanel contentPane;
private JTextField address;
private JPasswordField password;
private JTextField username;
private JButton btnLogin;
private JButton btnCancel;
private JLabel lblPort;
private JTextField port;
public boolean answer = false;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
DatabaseConnectionFrame frame = new DatabaseConnectionFrame();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame.
*/
public DatabaseConnectionFrame() {
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
setSize(450,250);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
GridBagLayout gbl_contentPane = new GridBagLayout();
contentPane.setLayout(gbl_contentPane);
JLabel lblDatabaseIpAddress = new JLabel("Database ip address:");
GridBagConstraints gbc_lblDatabaseIpAddress = new GridBagConstraints();
gbc_lblDatabaseIpAddress.anchor = GridBagConstraints.EAST;
gbc_lblDatabaseIpAddress.insets = new Insets(0, 0, 5, 5);
gbc_lblDatabaseIpAddress.gridx = 0;
gbc_lblDatabaseIpAddress.gridy = 0;
contentPane.add(lblDatabaseIpAddress, gbc_lblDatabaseIpAddress);
address = new JTextField();
GridBagConstraints gbc_textField = new GridBagConstraints();
gbc_textField.insets = new Insets(0, 0, 5, 0);
gbc_textField.fill = GridBagConstraints.HORIZONTAL;
gbc_textField.gridx = 1;
gbc_textField.gridy = 0;
contentPane.add(address, gbc_textField);
address.setColumns(10);
lblPort = new JLabel("Port");
GridBagConstraints gbc_lblPort = new GridBagConstraints();
gbc_lblPort.anchor = GridBagConstraints.EAST;
gbc_lblPort.insets = new Insets(0, 0, 5, 5);
gbc_lblPort.gridx = 0;
gbc_lblPort.gridy = 1;
contentPane.add(lblPort, gbc_lblPort);
port = new JTextField();
GridBagConstraints gbc_textField1 = new GridBagConstraints();
gbc_textField1.insets = new Insets(0, 0, 5, 0);
gbc_textField1.fill = GridBagConstraints.HORIZONTAL;
gbc_textField1.gridx = 1;
gbc_textField1.gridy = 1;
contentPane.add(port, gbc_textField1);
port.setColumns(10);
JLabel lblUsername = new JLabel("Username:");
lblUsername.setHorizontalAlignment(SwingConstants.CENTER);
GridBagConstraints gbc_lblUsername = new GridBagConstraints();
gbc_lblUsername.anchor = GridBagConstraints.EAST;
gbc_lblUsername.insets = new Insets(0, 0, 5, 5);
gbc_lblUsername.gridx = 0;
gbc_lblUsername.gridy = 2;
contentPane.add(lblUsername, gbc_lblUsername);
username = new JTextField();
GridBagConstraints gbc_textField_1 = new GridBagConstraints();
gbc_textField_1.insets = new Insets(0, 0, 5, 0);
gbc_textField_1.fill = GridBagConstraints.HORIZONTAL;
gbc_textField_1.gridx = 1;
gbc_textField_1.gridy = 2;
contentPane.add(username, gbc_textField_1);
username.setColumns(10);
JLabel lblPassword = new JLabel("Password");
GridBagConstraints gbc_lblPassword = new GridBagConstraints();
gbc_lblPassword.anchor = GridBagConstraints.EAST;
gbc_lblPassword.insets = new Insets(0, 0, 5, 5);
gbc_lblPassword.gridx = 0;
gbc_lblPassword.gridy = 3;
contentPane.add(lblPassword, gbc_lblPassword);
password = new JPasswordField();
GridBagConstraints gbc_passwordField = new GridBagConstraints();
gbc_passwordField.insets = new Insets(0, 0, 5, 0);
gbc_passwordField.fill = GridBagConstraints.HORIZONTAL;
gbc_passwordField.gridx = 1;
gbc_passwordField.gridy = 3;
contentPane.add(password, gbc_passwordField);
btnLogin = new JButton("Login");
GridBagConstraints gbc_btnLogin = new GridBagConstraints();
gbc_btnLogin.insets = new Insets(0, 0, 0, 5);
gbc_btnLogin.gridx = 0;
gbc_btnLogin.gridy = 4;
contentPane.add(btnLogin, gbc_btnLogin);
btnCancel = new JButton("Cancel");
GridBagConstraints gbc_btnCancel = new GridBagConstraints();
gbc_btnCancel.gridx = 1;
gbc_btnCancel.gridy = 4;
contentPane.add(btnCancel, gbc_btnCancel);
btnCancel.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
dispose();
}
});
btnLogin.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
String dbAddress = address.getText();
String dbPort = port.getText();
String dbUsername = username.getText();
char[] dbPassword = password.getPassword();
if( dbAddress.isEmpty() || dbPort.isEmpty() || dbUsername.isEmpty() || dbPassword.length == 0) {
JOptionPane.showMessageDialog(getParent(),
"All fields have to be filled!");
}
else {
if(databaseValidation(dbAddress, dbPort, dbUsername, dbPassword)) {
JOptionPane.showMessageDialog(getParent(),
"Connected!");
answer = true;
setVisible(false);
}
else {
JOptionPane.showMessageDialog(getParent(),
"There was error connecting to the database!");
answer = false;
}
}
System.out.println(answer);
}
});
}
public boolean databaseValidation(String address, String port, String username, char[] password) {
String pw = String.valueOf(password);
System.out.println(pw);
try {
Connection con = DriverManager.getConnection("jdbc:mysql://" + address + ":" + port + "/logctrl?user=" + username + "&password=" + pw );
} catch (SQLException e) {
System.out.println("Error connecting to database!");
return false;
}
System.out.println("Connected");
return true;
}
}
回答1:
If you want to wait for the user input, you have two choices, you either make your own observer pattern which can be called at some point in the future when the state changes in some way or you use a dialog, which will block the codes execution at the point the dialog is made visible and will wait till it's closed
See How to use dialogs for details
import java.awt.Frame;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
setLayout(new GridBagLayout());
JButton btn = new JButton("Show the dialog");
add(btn);
btn.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
JDialog dialog = new JDialog((Frame)SwingUtilities.getWindowAncestor(TestPane.this), "I'm in charge now", true);
JButton btn = new JButton("Waiting");
btn.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
dialog.dispose();
}
});
dialog.add(btn);
dialog.pack();
dialog.setLocationRelativeTo(TestPane.this);
dialog.setVisible(true);
JOptionPane.showMessageDialog(TestPane.this, "You won't see this till the dialog is closed");
}
});
}
}
}
来源：https://stackoverflow.com/questions/46294138/how-i-supposed-to-make-program-to-stop-and-wait-for-something-java