Question

起初，我很抱歉在Java，Swing和英语中都是noob。

我已经阅读了很多部分，但仍然不了解如何使用这三行......

removeAll();
revalidate(),
repaint();

这是我的问题。（因为大多数人都在谈论这个）我想刷新我的面板以删除JtextAreas并根据comboBox选择的项目添加新的。我创建了一个开关来做到这一点。我尝试了不同的地方来放置这些命令，但没有任何正常工作

我真的很抱歉，我当然会错过一些明显的东西，但我太初衷了，不能看到它。

这是我的代码:(我只是从我的主电话中调用它）

`public final class TestPane extends JFrame {

        public TestPane() throws ParseException {


 /********************* def layouts **********************/


JFrame desktop = new JFrame();  
desktop.setSize(new Dimension(1200, 200)); 

JPanel principalLayout = new JPanel();  
principalLayout.setLayout(new GridBagLayout()); 
GridBagConstraints  principalGrid = new GridBagConstraints();

principalGrid.fill=GridBagConstraints.BOTH;
desktop.add(principalLayout);


 /********************* def des contraintes **********************/

principalLayout.removeAll();
principalGrid.insets = new Insets(5, 5, 5, 5);
principalGrid.ipady = principalGrid.anchor = GridBagConstraints.CENTER;
principalGrid.weightx = 10;
principalGrid.weighty = 10;


 /**************** objets dans le gridBagLayout ******************/


String[] items = new String[4];
items[0] = ("DejAffaire");
items[1] = ("Hebergement");
items[2] = ("Kilometre");
    items[3] = ("Taxi");
JComboBox<String> comboChoixAdd = new JComboBox<>(items);
//comboChoixAdd.addActionListener(this);
JButton validAddFrais = new JButton("valider");
//validAddFrais.addActionListener(this);
JCheckBox checkKM = new JCheckBox("afficher frais kilométrique");
JCheckBox checkTaxi = new JCheckBox("afficher taxi");
JCheckBox checkDej = new JCheckBox("afficher frais repas");
JCheckBox checkHotel = new JCheckBox("afficher frais d'hébergement");


 /********* ajout dans le gridBagLayout + contraintes ************/


principalGrid.gridx = 0;
principalGrid.gridy = 0;
principalLayout.add(new JLabel("choix du type de frais :"), principalGrid);

//principalGrid.weightx = 2;
//principalGrid.weighty = 1;
principalGrid.gridx = 0;
principalGrid.gridy = 1;
principalLayout.add(comboChoixAdd, principalGrid);

principalGrid.gridx = 0;
principalGrid.gridy = 2;
principalLayout.add(validAddFrais, principalGrid);

principalGrid.gridx = 1;
principalGrid.gridy = 0;
principalGrid.gridwidth = 7;
principalLayout.add(new JLabel("entrer les champs du frais :"), principalGrid);

principalGrid.gridwidth = 1;
principalGrid.gridx = 0;
principalGrid.gridy = 3;
principalLayout.add(new JLabel("affichage des frais :"), principalGrid);


principalGrid.gridx = 2;
principalGrid.gridy = 3;
principalLayout.add(checkKM, principalGrid);

principalGrid.gridx = 3;
principalGrid.gridy = 3;
principalLayout.add(checkDej, principalGrid);

principalGrid.gridx = 4;
principalGrid.gridy = 3;
principalLayout.add(checkHotel, principalGrid);

principalGrid.gridx = 5;
principalGrid.gridy = 3;
principalLayout.add(checkTaxi, principalGrid);


desktop.setTitle("tests");
desktop.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
desktop.setVisible(true);




comboChoixAdd.addActionListener(new ActionListener() {//add actionlistner to listen for change
@Override
public void actionPerformed(ActionEvent e) {

    String s = (String) comboChoixAdd.getSelectedItem();//get the selected item

    switch (s) {
        case "DejAffaire":


            principalGrid.gridx = 1;
            principalGrid.gridy = 1;
            JTextArea text = new JTextArea();

            text.setText("test");
            text.setBounds(50, 50, 50, 50); 
            System.out.println(".actionPerformed()");
            principalLayout.add(text, principalGrid);
            principalLayout.revalidate();
            principalLayout.repaint();

            break;
        case "Hebergement":
            principalGrid.gridx = 1;
            principalGrid.gridy = 1;
            JTextArea textHotel = new JTextArea();

            textHotel.setText("azzzzzzzzzzzzzzzzeazeazeaze");
            textHotel.setBounds(50, 50, 50, 50); 
            System.out.println(".actionPerformed()");
            principalLayout.add(textHotel, principalGrid);
            //principalLayout.removeAll();
            principalLayout.revalidate();
            principalLayout.repaint();
            System.out.println(".actionPerformed()");
            break;
        case "Kilometre":
            System.out.println(".actionPerformed()");
            break;
        case "Taxi":
            System.out.println(".actionPerformed()");
            break;
    }
    System.out.println(".actionPerformed2()");
}
});
comboChoixAdd.setSelectedItem(items[3]);
    }




}`

Java swing removeALL + revalidate + repaint我不知道如何正确使用它们

0 个答案: