为什么赢得textField打印日期？

Question

为什么这个tidField.setText(date);不起作用？其他一切都有效，日期取自getDatum()，这是一个不同的类，在textArea.append(r.getLista());调用时效果很好，但tidField.setText(date);它不会改变字段

 final JComboBox<String> comboBox = new JComboBox<String>();
            comboBox.addItem("Företag");
            comboBox.addItem("Normal");
            comboBox.addItem("Student");
            comboBox.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent event) {
                    Kund kek = new Kund();
                    int kb = 0;
                    String date = kek.getDatum();
                    String SaldoString = "";
                    JComboBox<?> comboBox = (JComboBox<?>) event.getSource();
                    Object selected = comboBox.getSelectedItem();
                     if(selected.toString().equals("Normal")) {
                            Register r = new Register();
                            Kund k = new Normal();
                            k.setBelopp(100);
                            k.setDatum(date);
                            r.regKund(k);
                            int tempbelopp = k.getBelopp();
                            String b = Integer.toString(tempbelopp);
                            tidField.setText(date);
                            beloppField.setText(b);
                            kb = kb + 100;
                            SaldoString = Integer.toString(kb);
                            saldoText.setText(SaldoString);
                            textArea.append(r.getLista()); 
                            }
                        else if(selected.toString().equals("Student")) {
                            Register r = new Register();
                            Kund k = new Normal();
                            k=new Student();
                            k.setBelopp(50);
                            k.setDatum(date);
                            beloppField.setText(date);
                            tidField.setText(date);
                            if( kb >=50)
                                r.regKund(k);
                                kb = kb - 50;

                                                    textArea.append("Det finns inga cash, student reggades ej!" + "\n");

                    }
                        else if(selected.toString().equals("Företag")) {
                            Register r = new Register();
                            Kund k = new Normal();
                            k.setBelopp(0);
                            k.setDatum("20:17");
                            k.setLopnummer(r.getLopnummer());
                            r.regKund(k);
                            // Den skriver ut samma skit ändra det
                            textArea.append(r.getLista());
                            textArea.append("Kassan har nu "+kb+" kr" + "\n");
                        }

                }
            });
            comboBox.setToolTipText("Välj vilken typ av Kund du är");
            comboBox.setRenderer(new MyComboBoxRenderer("Välj..."));  
            //comboBox.setSelectedIndex(-1);
            comboBox.setBounds(171, 46, 97, 22);        
            frame.getContentPane().add(comboBox);


        }
        }

Answer 1

创建对象时是否为kek自动生成日期值？如果没有，那肯定是问题所在。

Answer 2

其他类的代码

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

public class Kund {

int belopp;
private String datum;

public Kund(){
    belopp=0;
    datum="";
}
// - Initiera attribut
public int getBelopp(){
    return belopp;

}
// - Returnera belopp
public void setBelopp(int b){
    belopp=b;
}
// - Sätta belopp
public String getDatum() {
    return datum;
}
// - Returnera datum
public void setDatum(String d) {
    DateFormat format = new SimpleDateFormat("HH:mm:ss");
    Date date = new Date();
    d = format.format(date);
    datum=d;
}
// - Sätta datum
public int nyBalans(int n) {
    return (n+this.getBelopp());
}
// - Returnera tidigare balans + aktuellt belopp
// - Överlagras i Student
public void setLopnummer(int x) {

}
// - Överlagras i Foretag

}



public class Frame extends Register {
private int TempInt;
    JFrame frame;


    /**
     * Launch the application.
     */
    public static void main(String[] args) {

        EventQueue.invokeLater(new Runnable() 
        {
            public void run() {
                try {
                    Frame window = new Frame();
                    window.frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }
    public void windowClosing (WindowEvent e) {
        JOptionPane.showMessageDialog(frame, "Programmet sparas och kommer nu stängas av");
        System.exit(1);
    }


    /**
     * Create the application.
     */
    public Frame() {

        initialize();
    }

    /**
     * Initialize the contents of the frame.
     */
    void initialize() {

        frame = new JFrame();
        frame.setBounds(100, 100, 450, 424);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().setLayout(null);




        final TextArea textArea = new TextArea();
        textArea.setEditable(false);        
        textArea.setBounds(0, 105, 440, 243);
        frame.getContentPane().add(textArea);


        // Använd k.setBelopp beroende på vilken man väljer


        String s = "";
        int il = beraknaSaldo();
        s = Integer.toString(il);
        final JTextPane saldoText = new JTextPane();
        saldoText.setText(s);
        saldoText.setEditable(false);
        saldoText.setBounds(208, 354, 42, 22);
        frame.getContentPane().add(saldoText);

        final TextField beloppField = new TextField();
        beloppField.setEditable(false);
        beloppField.setBounds(120, 10, 102, 22);
        frame.getContentPane().add(beloppField);


        final TextField tidField = new TextField();
        tidField.setEditable(false);
        tidField.setBounds(255, 10, 102, 22);
        frame.getContentPane().add(tidField);

        Label saldoLabel = new Label("Saldo:");
        saldoLabel.setBounds(162, 354, 40, 22);
        frame.getContentPane().add(saldoLabel);

        Label beloppLabel = new Label("Belopp:");
        beloppLabel.setBounds(72, 10, 50, 22);
        frame.getContentPane().add(beloppLabel);

        Label tidLabel = new Label("Tid:");
        tidLabel.setBounds(228, 10, 22, 22);
        frame.getContentPane().add(tidLabel);

        Label besökartypLabel = new Label("Bes\u00F6kartyp");
        besökartypLabel.setBounds(0, 77, 62, 22);
        frame.getContentPane().add(besökartypLabel);

        Label beloppLabel_1 = new Label("Belopp");
        beloppLabel_1.setBounds(122, 77, 62, 22);
        frame.getContentPane().add(beloppLabel_1);

        Label tidLabel_1 = new Label("Tid");
        tidLabel_1.setBounds(246, 77, 22, 22);
        frame.getContentPane().add(tidLabel_1);

        Label lopnrLabel = new Label("L\u00F6pnummer");
        lopnrLabel.setBounds(345, 77, 79, 22);
        frame.getContentPane().add(lopnrLabel);

        final JComboBox<String> comboBox = new JComboBox<String>();
        comboBox.addItem("Företag");
        comboBox.addItem("Normal");
        comboBox.addItem("Student");
        comboBox.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event) {
                Kund kek = new Kund();
                int kb = 0;
                String date = kek.getDatum();
                String SaldoString = "";
                JComboBox<?> comboBox = (JComboBox<?>) event.getSource();
                Object selected = comboBox.getSelectedItem();
                 if(selected.toString().equals("Normal")) {
                     textArea.append(date);
                        /*Register r = new Register();
                        Kund k = new Normal();
                        k.setBelopp(100);
                        k.setDatum(date);
                        r.regKund(k);
                        int tempbelopp = k.getBelopp();
                        String b = Integer.toString(tempbelopp);
                        tidField.setText(date);
                        beloppField.setText(b);
                        kb = kb + 100;
                        SaldoString = Integer.toString(kb);
                        saldoText.setText(SaldoString);
                        textArea.append(r.getLista()); */
                        }
                    else if(selected.toString().equals("Student")) {
                        Register r = new Register();
                        Kund k = new Normal();
                        k=new Student();
                        k.setBelopp(50);
                        k.setDatum(date);
                        beloppField.setText(date);
                        tidField.setText(date);
                        if( kb >=50)
                            r.regKund(k);
                            kb = kb - 50;

                                                textArea.append("Det finns inga cash, student reggades ej!" + "\n");

                }
                    else if(selected.toString().equals("Företag")) {
                        Register r = new Register();
                        Kund k = new Normal();
                        k.setBelopp(0);
                        k.setDatum("20:17");
                        k.setLopnummer(r.getLopnummer());
                        r.regKund(k);
                        // Den skriver ut samma skit ändra det
                        textArea.append(r.getLista());
                        textArea.append("Kassan har nu "+kb+" kr" + "\n");
                    }

            }
        });
        comboBox.setToolTipText("Välj vilken typ av Kund du är");
        comboBox.setRenderer(new MyComboBoxRenderer("Välj..."));  
        //comboBox.setSelectedIndex(-1);
        comboBox.setBounds(171, 46, 97, 22);        
        frame.getContentPane().add(comboBox);


    }
    }


class MyComboBoxRenderer extends JLabel implements ListCellRenderer<Object> {
    private String title;

    public MyComboBoxRenderer(String newTitle) {
        title = newTitle;
    }

    @Override
    public Component getListCellRendererComponent(JList<?> list, Object value, int index, boolean isSelected, boolean hasFocus) {
        if (index == -1 && value == null) setText(title );
        else setText(value.toString());
        return this;
    }
}

Answer 3

好的，问题似乎是在您的构造函数中，您正在设置datum = ""。在此之后，您永远不会实际使用setDatum()，因此当您第一次调用getDatum()时，您将返回一个空字符串。如果您更改构造函数以使其使用含义默认值，您应该会在第一次打印时发现，它会将此值添加到tidField。

只是为了测试这种情况，将datum = ""更改为datum = "hello"，以便您可以看到实际上正确应用文本。最重要的是你必须确定何时打电话给setDatum()。

在测试你的代码之后，你的文本字段可以从代码写入，但不能由用户编辑，所以考虑到你提供的代码，这似乎是你想要的效果。