Question

我正致力于为今年早些时候负责的程序创建基本GUI。我的目标是让程序执行时，显示的第一个屏幕是用户输入其名称的字段。按下回车键或提交按钮，然后将它们引导到另一个窗口，该窗口将播放器的名称嵌入为图层。

现在我不确定我是以最有效的方式做到这一点，但是通过阅读多个答案，创建单独的框架似乎是最好的方法，但如果我错了就纠正我。

执行

时出现以下错误

＆＃34;线程中的异常＆＃34; AWT-EventQueue-0＆＃34; 显示java.lang.NullPointerException＆＃34;

所以我首先运行loginpanel 代码：

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 loginPanel extends JFrame {

    public static void main(String[] args) {
        loginPanel loginFrame = new loginPanel();
    }

    private JButton submit;
    private JLabel playerName;
    private JTextField nameInput;
    public String name;

    JPanel panel = new JPanel();

    loginPanel() {
        setTitle("Game Data");
        setSize(300, 400);
        setLocationRelativeTo(null);

        submit = new JButton("Submit");
        submit.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event) {

                if (nameInput.getText().isEmpty()) {
                    JOptionPane.showMessageDialog(null, "Invalid Input, please try again");
                }

                else {
                    name = nameInput.getText();
                    gameDataPanel mainFrame = new gameDataPanel();
                    mainFrame.setVisible(true);
                    dispose();
                }
            }

        });

        playerName = new JLabel("Enter Player Name");

        nameInput = new JTextField(30);
        nameInput.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event) {

                if (nameInput.getText().isEmpty()) {
                    JOptionPane.showMessageDialog(null, "Invalid Input, please try again");
                }

                else {
                    name = nameInput.getText();

                    gameDataPanel mainFrame = new gameDataPanel();
                    mainFrame.setVisible(true);
                    dispose();
                }
            }

        });

        panel.add(playerName);
        panel.add(nameInput);
        panel.add(submit);

        getContentPane().add(panel);
        pack();
        setVisible(true);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    public String grabName() {
        return nameInput.getText();
    }

}

然后它应该在按下提交时运行：

import java.awt.Color;
import java.awt.Dimension;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class gameDataPanel extends JFrame {

    private JLabel playerName, gameName, gameScore, timePlayed;
    private JTextField gameNameField, gameScoreField, timePlayedField;
    private loginPanel login;
    private String name2;

    public static void main(String[] args) {
        gameDataPanel mainFrame = new gameDataPanel();
    }

    JPanel panel = new JPanel();

    gameDataPanel() {
        setTitle("Game Data Entry Program");
        setBackground(Color.WHITE);
        setPreferredSize(new Dimension(400, 300));


        name2 = login.name;

        playerName.setText(name2);

        panel.add(playerName);
        getContentPane().add(panel);
        pack();
        setVisible(true);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

}

问题是它永远不会超过第一个屏幕，任何帮助都表示赞赏。谢谢！

如何根据来自单独类的输入更改我的JLabel

0 个答案: