每次在JList上单击都可以重新绘制JPanel [英] repaint JPanel with every click at JList

问题描述

每次我单击JList项时，我都需要清除+刷新当前面板&加载另一个面板，通过方法"populateWithButtons()"返回. temp是一个int变量，用于存储在JList中单击的内容.我该如何纠正以下问题?

everytime i click on a JList item, i need to clear + refresh my current panel & load another panel, returned via method 'populateWithButtons()'. temp is an int variable that stores what was clicked at the JList. How do i rectify the following?

        list_1.addMouseListener(new MouseAdapter() {
                @Override
                public void mouseClicked(MouseEvent evt) {

                //refresh + populate JPanel
                Food food = new Food();             
                JPanel panel2 = new JPanel();
                JPanel pane11 = new JPanel();


                panel2.add(panel1);
                panel1.validate();
                panel1.repaint();
                panel1.setBounds(153, 74, 281, 269);

                panel1.add(food.populateWithButtons(temp));             
                contentPane.add(panel2);
        }

推荐答案

1. 不要使用 NullLayout

将 ListSelectionListener 添加到 JList 而不是

add ListSelectionListener to JList instead of MouseListener, otherwise you would need to convert point from mouse to Item in JList

使用 CardLayout 代替添加，在运行时删除 JPanel ，然后从ListSelectionListener中选择(ListSelectionModel到SINGLE ...)以切换准备好的卡(具有某些内容的JPanel)

use CardLayout instead of add, remove JPanels on runtime, then selection from ListSelectionListener (ListSelectionModel to SINGLE...) to switch prepared card (JPanel with some contents)

编辑

.

.

import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.util.Vector;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.ListSelectionModel;
import javax.swing.SwingUtilities;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;

public class CardlayoutTest {

    private Color[] colors = new Color[]{Color.BLACK, Color.RED, Color.GREEN, Color.BLUE};
    private JFrame frame = new JFrame();
    private JList list = new JList();
    private JPanel panel = new JPanel();
    private CardLayout card = new CardLayout();

    public CardlayoutTest() {
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        panel.setLayout(card);
        Vector<String> items = new Vector<String>();
        for (int x = 0; x < colors.length; x++) {
            JPanel pnl = new JPanel(new BorderLayout());
            pnl.setBackground(colors[x]);
            panel.add(pnl, colors[x].toString());
            items.add(colors[x].toString());
        }
        list = new JList(items);
        list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        list.getSelectionModel().addListSelectionListener(new ListSelectionListener() {
            @Override
            public void valueChanged(ListSelectionEvent e) {
                if (!e.getValueIsAdjusting()) {
                    String card = list.getSelectedValue().toString();
                    CardLayout cL = (CardLayout) (panel.getLayout());
                    cL.show(panel, card);
                }
            }
        });
        frame.add(new JScrollPane(list), BorderLayout.WEST);
        frame.add(panel);
        frame.setPreferredSize(new Dimension(400, 150));
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new CardlayoutTest();
            }
        });
    }
}

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