JFrame 和 JPanel 问题

Question

我正在尝试为当地一家销售糕点、百吉饼和咖啡的百吉饼店制作一个程序。我在实现我在 JFrame 中制作的面板时遇到了麻烦，

任何帮助理解如何使我的 JFrame 看起来像这样都会有帮助 http://kepler.covenant.edu/COS150/Bagel_files/image002.jpg

一旦我完成这项工作，我希望中间的面板集根据选择的产品而改变。我不完全确定如何使按钮和面板相互通信。

感谢您的帮助！

这是到目前为止我的 JFrame 代码。

import java.awt.BorderLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;

public class BagelOrder extends JFrame
{   
JLabel topLabel;

sizePanel sp = new sizePanel();
typePanel tp = new typePanel();
productsPanel pp = new productsPanel();
buttonPanel bp = new buttonPanel();
extrasPanel ep = new extrasPanel();

public BagelOrder()
{
    setTitle("Order Entry Screen");
    setSize(800, 800);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    topLabel = new JLabel("Order Entry Screen");
    add(pp, BorderLayout.WEST);
    add(topLabel, BorderLayout.NORTH);
    add(bp, BorderLayout.SOUTH);
    add(middleCoffeePanelSetBuild(), BorderLayout.CENTER);
    add(east, BorderLayout.EAST);
    setVisible(true);

}

private JPanel middleCoffeePanelSetBuild()
{
    JPanel middlePanel = new JPanel(new GridLayout(3,1));
    add(sp);
    add(tp);
    add(ep);

    }

public static void main(String args[])
{
    BagelOrder bo = new BagelOrder();
}



} 

我没有错误，但除了页面顶部的标签之外我看不到任何其他内容。

这是我的其他类

ButtonPanel

import java.awt.GridLayout;
import javax.swing.ButtonGroup;
import javax.swing.JButton;
import javax.swing.JPanel;


public class buttonPanel extends JPanel
{
JButton enterItemButton;
JPanel buttonPanel;
ButtonGroup bg;
JButton totalButton;
JButton newOrderButton;


public buttonPanel()
{
    buttonPanel = new JPanel(new GridLayout(1,3));
    bg = new ButtonGroup();
    enterItemButton = new JButton("Enter Item");
    totalButton = new JButton("Total");
    newOrderButton = new JButton("New Order");

    buttonPanel.setSize(150, 780);
    buttonPanel.add(enterItemButton);
    bg.add(enterItemButton);
    buttonPanel.add(totalButton);
    bg.add(totalButton);
    buttonPanel.add(newOrderButton);
    bg.add(newOrderButton);
    setVisible(true);   

}
}

ProductPanel

import java.awt.GridLayout;
import javax.swing.BorderFactory;
import javax.swing.ButtonGroup;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.border.Border;


public class productsPanel extends JPanel
{
public productsPanel()
{
    JPanel productPanel = new JPanel(new GridLayout(3,1));
    ButtonGroup bg = new ButtonGroup();
    JRadioButton coffeeButton = new JRadioButton("Coffee");
    JRadioButton bagelButton = new JRadioButton("Bagel");
    JRadioButton pastryButton = new JRadioButton("Pastry");

    productPanel.setSize(150, 780);
    productPanel.add(coffeeButton);
    bg.add(coffeeButton);
    productPanel.add(bagelButton);
    bg.add(bagelButton);
    productPanel.add(pastryButton);
    bg.add(pastryButton);

    Border etched = BorderFactory.createEtchedBorder();
    Border titled = BorderFactory.createTitledBorder(etched, "Products");
    productPanel.setBorder(titled);
    setVisible(true);   
}
}

Size Panel

import java.awt.GridLayout;

import javax.swing.BorderFactory;
import javax.swing.ButtonGroup;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.border.Border;


public class sizePanel extends JPanel{

public sizePanel()
{
    JPanel sp = new JPanel(new GridLayout(3,1));
    ButtonGroup bg = new ButtonGroup();
    JRadioButton smallButton = new JRadioButton("Small");
    JRadioButton mediumButton = new JRadioButton("Medium");
    JRadioButton largeButton = new JRadioButton("Large");

    sp.setSize(200, 200);
    sp.add(smallButton);
    bg.add(smallButton);
    sp.add(mediumButton);
    bg.add(mediumButton);
    sp.add(largeButton);
    bg.add(largeButton);


    Border etched = BorderFactory.createEtchedBorder();
    Border titled = BorderFactory.createTitledBorder(etched, "Size");   
    sp.setBorder(titled);
    setVisible(true);   
}
}

TypePanel

import java.awt.GridLayout;

import javax.swing.BorderFactory;
import javax.swing.ButtonGroup;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.border.Border;


public class typePanel extends JPanel
{
public typePanel()
{
    JPanel typePanel = new JPanel(new GridLayout(3,1));
    ButtonGroup bg = new ButtonGroup();
    JRadioButton regularButton = new JRadioButton("Regular");
    JRadioButton decafButton = new JRadioButton("Decaf");
    JRadioButton frenchRoastButton = new JRadioButton("French Roast");

    typePanel.setSize(200, 200);
    typePanel.add(regularButton);
    bg.add(regularButton);
    typePanel.add(decafButton);
    bg.add(decafButton);
    typePanel.add(frenchRoastButton);
    bg.add(frenchRoastButton);


    Border etched = BorderFactory.createEtchedBorder();
    Border titled = BorderFactory.createTitledBorder(etched, "Type");   
    typePanel.setBorder(titled);
    setVisible(true);   
}
}

ExtrasPanel的代码

 import java.awt.GridLayout;
 import javax.swing.BorderFactory;
 import javax.swing.JCheckBox;
 import javax.swing.JPanel;
 import javax.swing.border.Border;


public class extrasPanel extends JPanel
{
public extrasPanel()
{
    JPanel extrasPanel = new JPanel(new GridLayout(2,1));

    JCheckBox creamCheckBox = new JCheckBox("Cream");
    JCheckBox sugarCheckBox = new JCheckBox("Sugar");   

    extrasPanel.setSize(200, 200);
    extrasPanel.add(creamCheckBox);
    extrasPanel.add(sugarCheckBox);

    Border etched = BorderFactory.createEtchedBorder();
    Border titled = BorderFactory.createTitledBorder(etched, "Extras");
    extrasPanel.setBorder(titled);
    setVisible(true);
}
}

Answer 1

编写 Swing GUI 时需要遵循的一些良好实践：

1) 您的 Panel 类构建错误。
您需要重写 ButtonPanel 以及所有其他控件，以便它们读起来像这样：

public buttonPanel() {
    super(new GridLayout(1,3));
    bg = new ButtonGroup();
    enterItemButton = new JButton("Enter Item");
    totalButton = new JButton("Total");
    newOrderButton = new JButton("New Order");

    this.setSize(150, 780);
    this.add(enterItemButton);
    bg.add(enterItemButton);
    this.add(totalButton);
    bg.add(totalButton);
    this.add(newOrderButton);
    bg.add(newOrderButton);
    this.setVisible(true);

    }
}

按照您目前的编写方式，您有一个 ButtonPanel 类（始终大写类），它拥有一个带有按钮的 JPanel，但它从不显示它拥有的 JPanel。您需要 ButtonPanel 成为一个 JPanel，而不仅仅是拥有一个 JPanel。
这是主要问题。您可以改进的小点：

2) JFrame 有一个称为 contentPane 的 JPanel。正如 jzd 所说，当使用 JFrame.add 时，您实际上是在调用 JFrame.getContentPane.add(Component c)。这是一种方便的方法，但它隐藏了您真正在做什么。尤其是当你刚刚学习时，走捷径是不好的。

我个人更进一步，从

JPanel content = new JPanel(new BorderLayout());
content.add(...);
....
this.setContentPane(content);

3) 开始我的 JFrame，在扩展类（如 JFrame）时以调用 super() 开始是一个很好的做法。同样，您可以将其作为速记形式省略，但在开始时迂腐一点是有好处的。这会调用超类的构造函数（带有您需要的任何参数），这基本上是在说“让我们创建基本的 JFrame，然后对其应用我的扩展”。

4) 将类大写并以小写动词开头所有函数也是一个好习惯。即 ButtonPanel 或 build()

5) 看来您才刚刚开始使用 GUI，但我可以推荐外部库“MigLayout”（google 一下）。它的额外功能和易用性令人惊叹，它使您能够克服所有 Java 内置的、可怕的布局类型。

Answer 2

它们通过 ActionListener 接口、ActionPerformed(ActionEvent e) 方法相互通信，并且为了触发这些方法，您需要<要侦听的组件to>.addActionListener(theListener);