0

好的，所以我有一个带有一些文本字段和组合框的 GUI。每当我尝试获取文本时textField.getText()，comboBox.getSelectedItem()我都会得到一个空指针异常。即使我的组合框默认为一组String，或者我在 textField 中有文本。我运行GUI_preGame课程并将内容输入框中，然后调用getText().

抱歉，代码太乱了（部分原因是使用了窗口构建器组布局）我使用GUI_preGame.PetNames(); Error is with this line 从另一个调用这个类：498（我输入的打印语句只是为了打印它！） System.out.println(textField_3.getText().toString());

package tamagotchiAssignment;

import java.awt.BorderLayout;

public class GUI_preGame extends JFrame {

    private static JPanel contentPane;
    private static JTextField textField;
    private static JTextField textField_1;
    private static JTextField textField_2;
    private static JTextField textField_3;
    private static JTextField textField_4;
    private static JTextField textField_5;
    private static JTextField textField_6;
    private static JTextField textField_7;
    private static JTextField textField_8;
    private static JTextField textField_9;
    private static JTextField textField_10;
    private static JTextField textField_11;
    private static JComboBox comboBox_2;
    private static JComboBox comboBox_3;
    private JLabel lblPlayer_1;
    private JLabel lblPlayer_2;
    private JLabel lblPet_1;
    private JLabel lblPet_2;
    private JLabel label;
    private static JComboBox comboBox_7;
    private static JComboBox comboBox_8;
    private static JComboBox comboBox_9;
    private JLabel label_1;
    private static JComboBox comboBox_10;
    private static JComboBox comboBox_11;
    private static JComboBox comboBox_12;
    private JLabel lblPet_4;
    private JLabel lblPet_5;
    private static ArrayList<String> playerTexts = new ArrayList<String>();
    private static ArrayList<String> petTexts = new ArrayList<String>();
    private static ArrayList<String> speciesTexts = new ArrayList<String>();
    private static JComboBox comboBox_4;
    private static JComboBox comboBox_5;
    private static JComboBox comboBox_6;


    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    GUI_preGame frame = new GUI_preGame();
                    frame.setVisible(true);

                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public GUI_preGame() {
        setResizable(false);
        setTitle("Tamagotchi: Pre-Game");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 800, 600);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);

        JLabel lblNumberOfPlayers = new JLabel("Number of players:");
        lblNumberOfPlayers.setFont(new Font("Tahoma", Font.PLAIN, 14));

        final JComboBox comboBox = new JComboBox();
        comboBox.setModel(new DefaultComboBoxModel(new String[] {"3", "2", "1"}));

        JLabel lblPlayerNamesopt = new JLabel("Player names: (Optional)");
        lblPlayerNamesopt.setFont(new Font("Tahoma", Font.PLAIN, 14));

        JLabel lblNumberOfPets = new JLabel("Number of Pets:");
        lblNumberOfPets.setFont(new Font("Tahoma", Font.PLAIN, 14));

        textField = new JTextField();
        textField.setColumns(10);

        JComboBox comboBox_1 = new JComboBox();
        comboBox_1.setModel(new DefaultComboBoxModel(new String[] {"3", "2", "1"}));

        textField_1 = new JTextField();
        textField_1.setColumns(10);

        final JComboBox comboBox_2 = new JComboBox();
        comboBox_2.setModel(new DefaultComboBoxModel(new String[] {"3", "2", "1"}));

        textField_2 = new JTextField();
        textField_2.setColumns(10);

        comboBox_3 = new JComboBox();
        comboBox_3.setModel(new DefaultComboBoxModel(new String[] {"3", "2", "1"}));

        JLabel lblPetNamesoptional = new JLabel("Pet names: (Optional)");
        lblPetNamesoptional.setFont(new Font("Tahoma", Font.PLAIN, 14));

        JLabel lblPet = new JLabel("Pet 1");

        lblPet_1 = new JLabel("Pet 2");

        lblPet_2 = new JLabel("Pet 3");

        JLabel lblPlayer = new JLabel("Player 1");

        lblPlayer_1 = new JLabel("Player 2");

        lblPlayer_2 = new JLabel("Player 3");

        textField_3 = new JTextField();
        textField_3.setColumns(10);

        textField_4 = new JTextField();
        textField_4.setColumns(10);

        textField_5 = new JTextField();
        textField_5.setColumns(10);

        textField_6 = new JTextField();
        textField_6.setColumns(10);

        textField_7 = new JTextField();
        textField_7.setColumns(10);

        textField_8 = new JTextField();
        textField_8.setColumns(10);

        textField_9 = new JTextField();
        textField_9.setColumns(10);

        textField_10 = new JTextField();
        textField_10.setColumns(10);

        textField_11 = new JTextField();
        textField_11.setColumns(10);

        JButton btnCancel = new JButton("Cancel");
        btnCancel.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                System.exit(0);
            }
        }); 

        final JButton btnOk = new JButton("OK");
        btnOk.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                dispose();
            }
        }); 
        JLabel lblPetSpecies = new JLabel("Pet species:");
        lblPetSpecies.setFont(new Font("Tahoma", Font.PLAIN, 14));

        JLabel label_3 = new JLabel("Player 1");

        label = new JLabel("Player 2");

        label_1 = new JLabel("Player 3");

        comboBox_4 = new JComboBox();
        comboBox_4.setModel(new DefaultComboBoxModel(new String[] {"Mametchi", "Kuchipatchi", "Tarakotchi"}));

        comboBox_5 = new JComboBox();
        comboBox_5.setModel(new DefaultComboBoxModel(new String[] {"Kuchipatchi", "Mametchi", "Tarakotchi"}));

        comboBox_6 = new JComboBox();
        comboBox_6.setModel(new DefaultComboBoxModel(new String[] {"Tarakotchi", "Mametchi", "Kuchipatchi"}));

        comboBox_7 = new JComboBox();
        comboBox_7.setModel(new DefaultComboBoxModel(new String[] {"Mametchi", "Kuchipatchi", "Tarakotchi"}));

        comboBox_8 = new JComboBox();
        comboBox_8.setModel(new DefaultComboBoxModel(new String[] {"Kuchipatchi", "Mametchi", "Tarakotchi"}));

        comboBox_9 = new JComboBox();
        comboBox_9.setModel(new DefaultComboBoxModel(new String[] {"Tarakotchi", "Mametchi", "Kuchipatchi"}));

        comboBox_10 = new JComboBox();
        comboBox_10.setModel(new DefaultComboBoxModel(new String[] {"Mametchi", "Kuchipatchi", "Tarakotchi"}));

        comboBox_11 = new JComboBox();
        comboBox_11.setModel(new DefaultComboBoxModel(new String[] {"Kuchipatchi", "Mametchi", "Tarakotchi"}));

        comboBox_12 = new JComboBox();
        comboBox_12.setModel(new DefaultComboBoxModel(new String[] {"Tarakotchi", "Mametchi", "Kuchipatchi"}));

        JLabel lblPet_3 = new JLabel("Pet 1");

        lblPet_4 = new JLabel("Pet 2");

        lblPet_5 = new JLabel("Pet 3");

        JLabel lblDaysToPlay = new JLabel("Days to play:");
        lblDaysToPlay.setFont(new Font("Tahoma", Font.PLAIN, 14));

        JComboBox comboBox_13 = new JComboBox();
        comboBox_13.setModel(new DefaultComboBoxModel(new String[] {"1", "2", "5", "10", "15", "20", "30", "40", "50"}));



        GroupLayout gl_contentPane = new GroupLayout(contentPane);
        gl_contentPane.setHorizontalGroup(
            gl_contentPane.createParallelGroup(Alignment.LEADING)
                .addGroup(gl_contentPane.createSequentialGroup()
                    .addGap(267)
                    .addComponent(lblPet_3)
                    .addGap(69)
                    .addComponent(lblPet_4)
                    .addGap(88)
                    .addComponent(lblPet_5)
                    .addContainerGap(285, Short.MAX_VALUE))
                .addGroup(gl_contentPane.createSequentialGroup()
                    .addGap(272)
                    .addComponent(lblPet)
                    .addContainerGap(487, Short.MAX_VALUE))
                .addGroup(gl_contentPane.createSequentialGroup()
                    .addGap(185)
                    .addGroup(gl_contentPane.createParallelGroup(Alignment.LEADING)
                        .addGroup(gl_contentPane.createSequentialGroup()
                            .addComponent(lblDaysToPlay)
                            .addPreferredGap(ComponentPlacement.UNRELATED)
                            .addComponent(comboBox_13, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                            .addPreferredGap(ComponentPlacement.RELATED, 199, Short.MAX_VALUE)
                            .addComponent(btnOk, GroupLayout.PREFERRED_SIZE, 62, GroupLayout.PREFERRED_SIZE)
                            .addPreferredGap(ComponentPlacement.RELATED)
                            .addComponent(btnCancel)
                            .addGap(138))
                        .addGroup(gl_contentPane.createSequentialGroup()
                            .addGroup(gl_contentPane.createParallelGroup(Alignment.LEADING)
                                .addComponent(lblPetSpecies)
                                .addGroup(gl_contentPane.createSequentialGroup()
                                    .addComponent(lblPlayer_1)
                                    .addGap(18)
                                    .addComponent(textField_6, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                                    .addPreferredGap(ComponentPlacement.RELATED)
                                    .addComponent(textField_7, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                                    .addPreferredGap(ComponentPlacement.RELATED)
                                    .addComponent(textField_8, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                                .addGroup(gl_contentPane.createSequentialGroup()
                                    .addComponent(lblPlayer)
                                    .addGap(18)
                                    .addComponent(textField_3, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                                    .addPreferredGap(ComponentPlacement.RELATED)
                                    .addComponent(textField_4, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                                    .addPreferredGap(ComponentPlacement.RELATED)
                                    .addComponent(textField_5, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                                .addGroup(gl_contentPane.createSequentialGroup()
                                    .addGroup(gl_contentPane.createParallelGroup(Alignment.TRAILING)
                                        .addGroup(gl_contentPane.createSequentialGroup()
                                            .addGroup(gl_contentPane.createParallelGroup(Alignment.LEADING)
                                                .addComponent(lblPlayerNamesopt)
                                                .addComponent(textField, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                                                .addComponent(textField_1, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                                                .addComponent(textField_2, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                                                .addComponent(lblPetNamesoptional))
                                            .addGap(18))
                                        .addGroup(gl_contentPane.createSequentialGroup()
                                            .addComponent(lblNumberOfPlayers)
                                            .addPreferredGap(ComponentPlacement.UNRELATED)
                                            .addComponent(comboBox, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)))
                                    .addGroup(gl_contentPane.createParallelGroup(Alignment.LEADING)
                                        .addComponent(comboBox_2, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                                        .addComponent(comboBox_1, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                                        .addComponent(lblNumberOfPets)
                                        .addGroup(gl_contentPane.createSequentialGroup()
                                            .addGroup(gl_contentPane.createParallelGroup(Alignment.TRAILING)
                                                .addComponent(lblPet_1)
                                                .addComponent(comboBox_3, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                                            .addGap(69)
                                            .addComponent(lblPet_2))))
                                .addGroup(gl_contentPane.createSequentialGroup()
                                    .addGroup(gl_contentPane.createParallelGroup(Alignment.LEADING)
                                        .addGroup(gl_contentPane.createSequentialGroup()
                                            .addComponent(lblPlayer_2)
                                            .addGap(18)
                                            .addComponent(textField_9, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                                        .addGroup(gl_contentPane.createSequentialGroup()
                                            .addGroup(gl_contentPane.createParallelGroup(Alignment.LEADING)
                                                .addComponent(label_3, GroupLayout.PREFERRED_SIZE, 39, GroupLayout.PREFERRED_SIZE)
                                                .addComponent(label_1, GroupLayout.PREFERRED_SIZE, 39, GroupLayout.PREFERRED_SIZE))
                                            .addGap(26)
                                            .addGroup(gl_contentPane.createParallelGroup(Alignment.LEADING)
                                                .addComponent(comboBox_7, 0, 90, Short.MAX_VALUE)
                                                .addComponent(comboBox_4, 0, 90, Short.MAX_VALUE)
                                                .addComponent(comboBox_10, 0, 90, Short.MAX_VALUE))))
                                    .addPreferredGap(ComponentPlacement.RELATED)
                                    .addGroup(gl_contentPane.createParallelGroup(Alignment.LEADING)
                                        .addGroup(gl_contentPane.createSequentialGroup()
                                            .addComponent(textField_10, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                                            .addPreferredGap(ComponentPlacement.RELATED)
                                            .addComponent(textField_11, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                                        .addGroup(gl_contentPane.createSequentialGroup()
                                            .addGap(8)
                                            .addGroup(gl_contentPane.createParallelGroup(Alignment.LEADING)
                                                .addComponent(comboBox_5, 0, 95, Short.MAX_VALUE)
                                                .addComponent(comboBox_8, 0, 95, Short.MAX_VALUE)
                                                .addComponent(comboBox_11, 0, 95, Short.MAX_VALUE))
                                            .addGap(18)
                                            .addGroup(gl_contentPane.createParallelGroup(Alignment.LEADING, false)
                                                .addComponent(comboBox_6, 0, 96, Short.MAX_VALUE)
                                                .addComponent(comboBox_9, 0, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                                                .addComponent(comboBox_12, 0, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)))))
                                .addGroup(gl_contentPane.createSequentialGroup()
                                    .addComponent(label, GroupLayout.PREFERRED_SIZE, 39, GroupLayout.PREFERRED_SIZE)
                                    .addPreferredGap(ComponentPlacement.RELATED, 339, Short.MAX_VALUE)))
                            .addGap(221))))
        );
        gl_contentPane.setVerticalGroup(
            gl_contentPane.createParallelGroup(Alignment.LEADING)
                .addGroup(gl_contentPane.createSequentialGroup()
                    .addGap(22)
                    .addGroup(gl_contentPane.createParallelGroup(Alignment.LEADING)
                        .addGroup(gl_contentPane.createSequentialGroup()
                            .addGap(35)
                            .addGroup(gl_contentPane.createParallelGroup(Alignment.BASELINE)
                                .addComponent(lblPlayerNamesopt)
                                .addComponent(lblNumberOfPets)))
                        .addGroup(gl_contentPane.createParallelGroup(Alignment.BASELINE)
                            .addComponent(comboBox, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                            .addComponent(lblNumberOfPlayers)))
                    .addPreferredGap(ComponentPlacement.RELATED)
                    .addGroup(gl_contentPane.createParallelGroup(Alignment.LEADING)
                        .addComponent(textField, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                        .addComponent(comboBox_1, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                    .addPreferredGap(ComponentPlacement.RELATED)
                    .addGroup(gl_contentPane.createParallelGroup(Alignment.LEADING)
                        .addComponent(textField_1, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                        .addComponent(comboBox_2, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                    .addPreferredGap(ComponentPlacement.RELATED)
                    .addGroup(gl_contentPane.createParallelGroup(Alignment.LEADING)
                        .addComponent(textField_2, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                        .addComponent(comboBox_3, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                    .addGap(18)
                    .addComponent(lblPetNamesoptional)
                    .addPreferredGap(ComponentPlacement.RELATED)
                    .addGroup(gl_contentPane.createParallelGroup(Alignment.BASELINE)
                        .addComponent(lblPet)
                        .addComponent(lblPet_2)
                        .addComponent(lblPet_1))
                    .addPreferredGap(ComponentPlacement.RELATED)
                    .addGroup(gl_contentPane.createParallelGroup(Alignment.BASELINE)
                        .addComponent(lblPlayer)
                        .addComponent(textField_3, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                        .addComponent(textField_4, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                        .addComponent(textField_5, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                    .addPreferredGap(ComponentPlacement.RELATED)
                    .addGroup(gl_contentPane.createParallelGroup(Alignment.BASELINE)
                        .addComponent(lblPlayer_1)
                        .addComponent(textField_6, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                        .addComponent(textField_7, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                        .addComponent(textField_8, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                    .addPreferredGap(ComponentPlacement.RELATED)
                    .addGroup(gl_contentPane.createParallelGroup(Alignment.BASELINE)
                        .addComponent(lblPlayer_2)
                        .addComponent(textField_9, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                        .addComponent(textField_10, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                        .addComponent(textField_11, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                    .addGap(18)
                    .addGroup(gl_contentPane.createParallelGroup(Alignment.TRAILING)
                        .addComponent(lblPet_3)
                        .addGroup(gl_contentPane.createSequentialGroup()
                            .addComponent(lblPetSpecies)
                            .addGap(9)
                            .addGroup(gl_contentPane.createParallelGroup(Alignment.BASELINE)
                                .addComponent(lblPet_4)
                                .addComponent(lblPet_5))))
                    .addPreferredGap(ComponentPlacement.RELATED)
                    .addGroup(gl_contentPane.createParallelGroup(Alignment.BASELINE)
                        .addComponent(label_3)
                        .addComponent(comboBox_4, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                        .addComponent(comboBox_5, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                        .addComponent(comboBox_6, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                    .addGap(18)
                    .addGroup(gl_contentPane.createParallelGroup(Alignment.BASELINE)
                        .addComponent(label)
                        .addComponent(comboBox_7, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                        .addComponent(comboBox_8, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                        .addComponent(comboBox_9, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                    .addGap(18)
                    .addGroup(gl_contentPane.createParallelGroup(Alignment.BASELINE)
                        .addComponent(label_1)
                        .addComponent(comboBox_10, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                        .addComponent(comboBox_11, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                        .addComponent(comboBox_12, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE))
                    .addGap(42)
                    .addGroup(gl_contentPane.createParallelGroup(Alignment.BASELINE)
                        .addComponent(lblDaysToPlay)
                        .addComponent(comboBox_13, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                        .addComponent(btnOk)
                        .addComponent(btnCancel))
                    .addGap(52))
        );
        contentPane.setLayout(gl_contentPane);
        }

    public static ArrayList<String> PetNames() {
        System.out.println(textField_3.getText().toString());
        petTexts.add(textField_3.getText().toString());
        petTexts.add(textField_4.getText());
        petTexts.add(textField_5.getText());
        petTexts.add(textField_6.getText());
        petTexts.add(textField_7.getText());
        petTexts.add(textField_8.getText());
        petTexts.add(textField_9.getText());
        petTexts.add(textField_10.getText());
        petTexts.add(textField_11.getText());
        return petTexts;
    }

    public static ArrayList<String> playerNames() {
        playerTexts.add(textField.getText());
        playerTexts.add(textField_1.getText());
        playerTexts.add(textField_2.getText());
        return playerTexts;
    }
    public static ArrayList<String> speciesNames() {
        System.out.println("hello");
        speciesTexts.add(comboBox_4.getSelectedItem().toString());
        speciesTexts.add(comboBox_5.getSelectedItem().toString());
        speciesTexts.add(comboBox_6.getSelectedItem().toString());
        speciesTexts.add(comboBox_7.getSelectedItem().toString());
        speciesTexts.add(comboBox_8.getSelectedItem().toString());
        speciesTexts.add(comboBox_9.getSelectedItem().toString());
        speciesTexts.add(comboBox_10.getSelectedItem().toString());
        speciesTexts.add(comboBox_11.getSelectedItem().toString());
        return speciesTexts;
    }
    public void disablePlayer23() {
        disablePlayer2();
        disablePlayer3();
    }

    public void disablePlayer2() {
        textField_1.setEnabled(false);
        comboBox_2.setEnabled(false);
        textField_6.setEnabled(false);
        textField_7.setEnabled(false);
        textField_8.setEnabled(false);
        lblPlayer_1.setEnabled(false);
        comboBox_7.setEnabled(false);
        comboBox_8.setEnabled(false);
        comboBox_9.setEnabled(false);
        label.setEnabled(false);
    }

    public void enablePlayer2() {
        textField_1.setEnabled(true);
        comboBox_2.setEnabled(true);
        textField_6.setEnabled(true);
        textField_7.setEnabled(true);
        textField_8.setEnabled(true);
        lblPlayer_1.setEnabled(true);
        comboBox_7.setEnabled(true);
        comboBox_8.setEnabled(true);
        comboBox_9.setEnabled(true);
        label.setEnabled(true);
    }

    public void disablePlayer3() {
        textField_2.setEnabled(false);
        comboBox_3.setEnabled(false);
        textField_9.setEnabled(false);
        textField_10.setEnabled(false);
        textField_11.setEnabled(false);
        lblPlayer_2.setEnabled(false);
        comboBox_10.setEnabled(false);
        comboBox_11.setEnabled(false);
        comboBox_12.setEnabled(false);
        label_1.setEnabled(false);
    }

    public void enablePlayer3() {
        textField_2.setEnabled(true);
        comboBox_3.setEnabled(true);
        textField_9.setEnabled(true);
        textField_10.setEnabled(true);
        textField_11.setEnabled(true);
        lblPlayer_2.setEnabled(true);
        comboBox_10.setEnabled(true);
        comboBox_11.setEnabled(true);
        comboBox_12.setEnabled(true);
        label_1.setEnabled(true);
    }

    public void enablePlayer23() {
        enablePlayer2();
        enablePlayer3();    
    }

    public void disableP2Pet23() {
        disableP2Pet2();
        disableP2Pet3();
    }

    public void disableP2Pet2() {
        textField_7.setEnabled(false);
        comboBox_8.setEnabled(false);
    }

    public void disableP2Pet3() {
        textField_8.setEnabled(false);
        comboBox_9.setEnabled(false);
    }

    public void enableP2Pet2() {
        textField_7.setEnabled(true);
        comboBox_8.setEnabled(true);
    }

    public void enableP2Pet3() {
        textField_8.setEnabled(true);
        comboBox_9.setEnabled(true);
    }

    public void enableP2Pet23() {
        enableP2Pet2();
        enableP2Pet3();
    }
}
4

2 回答 2

1

您的所有字段都在GUI_preGame的构造函数中初始化。

不过，作为PetNames()一种static方法，您可以访问它而无需先调用GUI_preGame' 的构造函数。

当你这样做时，由于所有这些textField_*对象都没有被初始化，它们将被初始化，null并且任何从它们执行方法的尝试都会抛出一个NullPointerException.

解决方案：将其设置PetNames()为非静态，static使其附加到一个GUI_preGame实例（仅在调用 的构造函数时才会存在GUI_preGame），或者更好的是，将PetNames() 所有其他 static方法和字段设置为非静态，因为您的代码现在正在制作对该功能的不当使用static：

public static ArrayList<String> PetNames() { //<-- remove "static" from this line
    System.out.println(textField_3.getText().toString());
    petTexts.add(textField_3.getText().toString());
    petTexts.add(textField_4.getText());
    petTexts.add(textField_5.getText());
    petTexts.add(textField_6.getText());
    petTexts.add(textField_7.getText());
    petTexts.add(textField_8.getText());
    petTexts.add(textField_9.getText());
    petTexts.add(textField_10.getText());
    petTexts.add(textField_11.getText());
    return petTexts;
}
于 2013-05-25T02:37:46.020 回答
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  1. 不要static以这种方式使用。它带有糟糕的设计的味道，并且只会限制您从长远来看可以实现的目标。
  2. 你正在隐藏你的变量......

例如，您声明一个类级别的字段...

private static JComboBox comboBox_2;

但是在您的构造函数中，您将其重新声明为局部变量...

final JComboBox comboBox_2 = new JComboBox();

这意味着类级别字段仍然是null

于 2013-05-25T02:39:42.453 回答