将JPanel添加到具有布局的JPanel

Question

我有一个JPanel可以显示我的主要GUI。 在该主面板上，我想添加其他JPanels来显示项目的描述，并允许您购买和出售它。 我的主面板和ItemPanel都使用FlowLayout。 这些是类：

主面板

package me.phination.clicker.gui;

import javax.swing.JPanel;

public class MainPanel extends JPanel {

    private JLabel batchLabel;
    private JButton btnMakeBatch;
    private JButton btnSellBatch;
    private JLabel moneyLabel;
    private JTextArea textArea;
    private JPanel itemPanel;


    public MainPanel() {
        setBackground(new Color(153, 51, 0));
        SpringLayout springLayout = new SpringLayout();
        setLayout(springLayout);

            //add the item panel to this panel
        itemPanel = new ItemPanel();
        itemPanel.setSize(200, 100);
        add(itemPanel);
    }

    public void consoleMsg(String msg) {
        textArea.append(msg + "\n");
        textArea.setCaretPosition(textArea.getDocument().getLength());
    }
}

项目面板

package me.phination.clicker.game;

import javax.swing.JPanel;
import javax.swing.SpringLayout;
import javax.swing.JLabel;
import javax.swing.JButton;
import java.awt.Font;

public class ItemPanel extends JPanel {
        public ItemPanel() {
                SpringLayout springLayout = new SpringLayout();
                setLayout(springLayout);

                JLabel lblItemName = new JLabel("Item name");
                lblItemName.setFont(new Font("Lucida Grande", Font.BOLD, 18));
                springLayout.putConstraint(SpringLayout.NORTH, lblItemName, 10, SpringLayout.NORTH, this);
                add(lblItemName);

                JLabel lblAmountOwned = new JLabel("Amount owned");
                springLayout.putConstraint(SpringLayout.WEST, lblAmountOwned, 10, SpringLayout.WEST, this);
                springLayout.putConstraint(SpringLayout.WEST, lblItemName, 0, SpringLayout.WEST, lblAmountOwned);
                springLayout.putConstraint(SpringLayout.SOUTH, lblAmountOwned, -10, SpringLayout.SOUTH, this);
                add(lblAmountOwned);

                JButton btnPurchase = new JButton("Purchase");
                springLayout.putConstraint(SpringLayout.NORTH, btnPurchase, 0, SpringLayout.NORTH, lblItemName);
                springLayout.putConstraint(SpringLayout.EAST, btnPurchase, -10, SpringLayout.EAST, this);
                add(btnPurchase);

                JButton btnSell = new JButton("Sell");
                springLayout.putConstraint(SpringLayout.SOUTH, btnSell, -10, SpringLayout.SOUTH, this);
                springLayout.putConstraint(SpringLayout.EAST, btnSell, 0, SpringLayout.EAST, btnPurchase);
                add(btnSell);

                JLabel lblDescription = new JLabel("Description");
                springLayout.putConstraint(SpringLayout.NORTH, lblDescription, 6, SpringLayout.SOUTH, lblItemName);
                springLayout.putConstraint(SpringLayout.WEST, lblDescription, 0, SpringLayout.WEST, lblItemName);
                add(lblDescription);
        }
}

我遇到的问题是，如果我在ItemPanel中使用Spring，将其添加到主面板后，它什么也没有显示。 如果我不在ItemPanel中使用布局，则显示效果很好，但是如果我将其单独添加到JFrame中，则它没有ItemPanel的漂亮布局。

Answer 1

您没有在用于SpringLayout的ItemPanel上施加任何约束，因此它不会扩展或不知道MainPanel中要占用多少空间。 当我向面板添加约束时，它出现了。 尝试添加它，看看是否出现您的面板。

springLayout.putConstraint(SpringLayout.NORTH, itemPanel, 22, SpringLayout.SOUTH, btnMakeBatch);
springLayout.putConstraint(SpringLayout.WEST, itemPanel, 43, SpringLayout.WEST, this);
springLayout.putConstraint(SpringLayout.EAST, itemPanel, -104, SpringLayout.EAST, this);

您是在手动设计，然后按“运行”以查看它，还是使用例如WindowBuilder ？