Question

我正在制作一个非常基本的登录提示GUI，用于下周我的Java考试的修订（这个练习可能会出现在考试中，所以这就是为什么我要先试试它）。基本上当你输入某个名字时，在这种情况下'joe'它会说已经过验证，否则它会说未经验证。然而，即使我输入乔，它仍然会说未经证实。谁能看到我出错的地方？谢谢。

package gui.eventHandler;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;  
import javax.swing.JPanel;
import javax.swing.JTextField;

public class EventHandlerExample2_NameConfirmation {

private JFrame frame;
private JPanel panel;
private JButton button1;
private JLabel label;
private JTextField fname;

public EventHandlerExample2_NameConfirmation() {

    frame = new JFrame("Log In");
    panel = new JPanel();
    label = new JLabel("First Name: ");
    fname = new JTextField(20);

    // Actions for when the OK button is clicked
    // Implementing the ActionListener as an anonymous inner class
    button1 = new JButton("Submit");
    button1.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {

            String inputname = fname.getText();

            if (inputname == "joe") {
                JOptionPane.showMessageDialog(null, "Verified user " + inputname);
            } else {
                //selects this option regardless of entry
                JOptionPane.showMessageDialog(null, "Invalid user " + inputname);
            }

        }
    });

    panel.add(label); // add the label
    panel.add(fname); // textField
    panel.add(button1); // and button to the panel

    frame.add(panel); // add panel onto the frame
    frame.setVisible(true); // By default its invisible
    frame.setSize(600, 70); // 600 width 70 height
    frame.setLocation(350, 350); // roughly center screen
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // exit when closed

}

public static void main(String[] args) {
    EventHandlerExample2_NameConfirmation app = new EventHandlerExample2_NameConfirmation();
}

}

Answer 1

使用string.equals比较字符串operator ==检查对字符串的引用是否相等

GUI中的If语句出错（始终属于ELSE，从不IF）

1 个答案: