java - 两个 Jpanel 未显示在 Jframe 中

Question

我不明白为什么 mediaPanel 和 selectedMediaPanel 没有显示在 JFrame 中。原因是什么？

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Arrays;
import java.util.List;
import java.util.Vector;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.ListSelectionModel;


public class MediaSelectionGUI {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub

        new MediaSelectionGUI();

    }

    public MediaSelectionGUI(){

        final Situation situation = new Situation();

        JFrame guiFrame = new JFrame();

        //make sure the program exits when the frame closes
        guiFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        guiFrame.setTitle("Communications Support Tool version 0.1");
        guiFrame.setSize(1000,500);
        guiFrame.setLayout(new FlowLayout());


      //This will center the JFrame in the middle of the screen
        guiFrame.setLocationRelativeTo(null);

        Vector<Media> media_option = new Vector<Media>(Arrays.asList(new Media[]{Media.Chat,Media.E_mail,Media.Intranet,Media.Meeting,Media.Social_Media, Media.Telefon, Media.Video}));
        Vector<Media> selected_media_option = new Vector<Media>();

        Zweck[] zweck_option = {Zweck.Anweisung, Zweck.Austausch, Zweck.Informieren, Zweck.Koordination};
        Ort[] ort_option = {Ort.Gleicher_Ort, Ort.Unterschiedlicher_Ort, Ort.Andere_Zeitzone};
        Anzahl[] anzahl_option = {Anzahl.Zwei_Personen, Anzahl.Klein_Gruppe, Anzahl.Publikum};

      //Create the second JPanel. Add a JLabel and JList and
        final JPanel mediaPanel = new JPanel(null);
        JLabel mediaLabel = new JLabel("All Media:");
        final JList<Media> media = new JList<Media>(media_option);
        media.setLayoutOrientation(JList.HORIZONTAL_WRAP);
        media.setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);

        mediaPanel.add(mediaLabel);
        mediaPanel.add(media);
        mediaPanel.setVisible(true);

        final JPanel selectedMediaPanel = new JPanel(null);
        JLabel selectedmediaLabel = new JLabel("Selected Media:");
        final JList<Media> selected_media = new JList<Media>(selected_media_option);
        selected_media.setLayoutOrientation(JList.HORIZONTAL_WRAP);
        selected_media.setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);

        selectedMediaPanel.add(selectedmediaLabel);
        selectedMediaPanel.add(selected_media);
        selectedMediaPanel.setVisible(true);

        JButton select_button = new JButton("select");
        JButton deselect_button = new JButton("deselect");

        select_button.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent event) {
                // TODO Auto-generated method stub
                List<Media> selected_media_option = media.getSelectedValuesList();
                for (Media medium: selected_media_option){
                    selected_media.getSelectedValuesList().add(medium);
                }
            }
        });


        deselect_button.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent event) {
                // TODO Auto-generated method stub
                List<Media> selected_media_option = selected_media.getSelectedValuesList();
                for (Media medium: selected_media_option){
                    media.getSelectedValuesList().add(medium);
                }
            }
        });

        select_button.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent event) {
                // TODO Auto-generated method stub
                List<Media> selected_media_option = media.getSelectedValuesList();
                for (Media medium: selected_media_option){
                    situation.media_collection.add(medium);
                    System.out.println(medium);
                }
            }
        });


      // Zweck Panel
        final JPanel zweckPanel = new JPanel();
        JLabel zweckLabel = new JLabel("Zweck:");
        JComboBox<Zweck> zweck = new JComboBox<Zweck>(zweck_option);
        zweckPanel.add(zweckLabel);
        zweckPanel.add(zweck);

     // Ort Panel
        final JPanel ortPanel = new JPanel();
        JLabel ortLabel = new JLabel("Ort:");
        JComboBox<Ort> ort = new JComboBox<Ort>(ort_option);    
        ortPanel.add(ortLabel);
        ortPanel.add(ort);

     // Anzahl Panel
        final JPanel anzahlPanel = new JPanel();
        JLabel anzahlLabel = new JLabel("Anzahl:");
        JComboBox<Anzahl> anzahl = new JComboBox<Anzahl>(anzahl_option);
        ortPanel.add(anzahlLabel);
        ortPanel.add(anzahl);


        guiFrame.add(mediaPanel);
        guiFrame.add(select_button);
        guiFrame.add(deselect_button);
        guiFrame.add(selectedMediaPanel);
        guiFrame.add(zweckPanel);
        guiFrame.add(ortPanel);
        guiFrame.add(anzahlPanel);

        guiFrame.setVisible(true);
    }

}

Answer 1

您遇到问题的主要原因是您向使用布局管理器的框架添加了两个具有空布局的面板。

框架布局管理器正在检查这些面板的首选尺寸，并且它们返回 0x0。所以你的面板正在显示，它们的大小只是0x0

尝试为面板使用适当的布局管理器