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私は間違った認証に関するメッセージを表示するためにloginLabelというラベルを作成しました。私はactionPerformedメソッド内にこのロジックを保持していますが、私はloginLabel can not be resolvedというエラーが発生しています。このエラーを取り除くには？私はウィンドウビルダを使ってGUIを作成しました。ラベル名を解決できません
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.LineBorder;
import java.awt.Color;
import javax.swing.JLabel;
import java.awt.Font;
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 FirstView {
private JFrame frmFirstProject;
private JTextField txtUsername;
private JPasswordField txtPassword;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
FirstView window = new FirstView();
window.frmFirstProject.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public FirstView() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frmFirstProject = new JFrame();
frmFirstProject.getContentPane().setBackground(new Color(51, 204, 204));
frmFirstProject.setTitle("first project");
frmFirstProject.setBounds(100, 100, 714, 491);
frmFirstProject.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frmFirstProject.getContentPane().setLayout(null);
JPanel panel = new JPanel();
panel.setBorder(new LineBorder(new Color(0, 0, 0), 3));
panel.setBounds(63, 47, 580, 354);
frmFirstProject.getContentPane().add(panel);
panel.setLayout(null);
JLabel lblUsername = new JLabel("Username:");
lblUsername.setBounds(24, 25, 69, 22);
panel.add(lblUsername);
JLabel lblPassword = new JLabel("Password:");
lblPassword.setBounds(24, 66, 69, 22);
panel.add(lblPassword);
txtUsername = new JTextField();
txtUsername.setBounds(97, 26, 86, 20);
panel.add(txtUsername);
txtUsername.setColumns(10);
txtPassword = new JPasswordField();
txtPassword.setBounds(97, 67, 86, 20);
panel.add(txtPassword);
JButton btnsubmit = new JButton("submit");
frmFirstProject.getRootPane().setDefaultButton(btnsubmit); //enter key
btnsubmit.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
try {
int val = 0;
Connection sqlCon = DB_con.getSQLConnection();
PreparedStatement ps = sqlCon.prepareStatement("select 1 from tbl_user_info where username = ? and password = ?");
ps.setString(1, txtUsername.getText().toUpperCase());
ps.setString(2, String.valueOf(txtPassword.getPassword()).toUpperCase());
ResultSet rs = ps.executeQuery();
if (rs.next()) {
val = rs.getInt(1);
}
if(val != 1)
{
loginLabel.setVisible(true);
}
System.out.println("the value is: "+val);
sqlCon.close();
System.exit(0);
} catch (Exception e) {
System.out.println(e.toString());
}
}
});
btnsubmit.setBounds(94, 125, 89, 23);
panel.add(btnsubmit);
JPanel panel_display = new JPanel();
panel_display.setBounds(36, 181, 355, 50);
panel.add(panel_display);
panel_display.setLayout(null);
JLabel loginLabel = new JLabel("Login Authentication Mismatched. Please try again.");
loginLabel.setFont(new Font("Tahoma", Font.PLAIN, 13));
loginLabel.setBounds(10, 11, 319, 28);
panel_display.add(loginLabel);
loginLabel.setVisible(false);
JLabel lbl_header = new JLabel("LIBRARY MANAGEMENT SYSTEM");
lbl_header.setFont(new Font("Tahoma", Font.BOLD, 14));
lbl_header.setBounds(211, 11, 288, 25);
frmFirstProject.getContentPane().add(lbl_header);
}
}
インスタンスフィールドに 'loginLabel'を設定するか、' ActionListener'の前に宣言する必要があります – MadProgrammer
この質問の更新はありますか？ –