使用Java swing将面板添加到容器中

Question

我制作了两个面板，然后在第三个面板中添加。如何添加面板以显示在屏幕上？

这是我目前的代码：

import javax.swing.*;
import java.awt.*;

public class LibraryFront {

public static void main(String[] args)
{

    JFrame f1 = new JFrame();
    JPanel cards;
    final String BUTTONPANEL = "Card with JButtons";
    final String TEXTPANEL = "Card with JTextField";

    JPanel card1 = new JPanel();
    JPanel card2 = new JPanel();

    // Create the panel that contains the "cards".
    cards = new JPanel(new CardLayout());
    cards.add(card1, BUTTONPANEL);
    cards.add(card2, TEXTPANEL);

    Container c = getContentPane(); //this gives error
}

Answer 1

LibraryFront不是容器。 JFrame f1是，f1.getContentPane()应该可以使用，您还需要将面板添加到JFrame并将其设置为可见（如果不可见）。

Answer 2

修改
 我现在注意到您从http://download.oracle.com/javase/tutorial/uiswing/layout/card.html获取了代码段（部​​分）并将其直接放入主方法中。该代码只是CardLayoutDemo.java完整计划实施的一部分。您需要查看该代码。

您的代码存在很多小错误。这是一个有效的实现

//it is good practice to only import the packages you need
//so that you know exactly what you are dealing with
import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Color;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class LibraryFront {

    public static void main(String[] args) {
        //f1 is the JFrame
        //f1.getContentPane() would return the Container
        //but you do not actually need to add directly to it
        JFrame f1 = new JFrame();
        JPanel cards;
        final String BUTTONPANEL = "Card with JButtons";
        final String TEXTPANEL = "Card with JTextField";

        JPanel card1 = new JPanel();
        JPanel card2 = new JPanel();

        // Create the panel that contains the "cards".
        cards = new JPanel(new CardLayout());
        cards.add(card1, BUTTONPANEL);
        cards.add(card2, TEXTPANEL);

        //adjust background colors just so you can see what is happening
        cards.setBackground(Color.GREEN);
        card1.setBackground(Color.RED);
        card2.setBackground(Color.BLUE);

        //set the layout to BorderLayout
        // add the cards JPanel to the center
        f1.setLayout(new BorderLayout());
        f1.add(cards, BorderLayout.CENTER);
        f1.setSize(400, 300);
        f1.setTitle("Test Frame");
        f1.setVisible(true);
    }
}

Answer 3

尝试：

Container c = f1.getContentPane();

在JFrame上调用该方法，而不是在您自己的LibraryFront班级。

Answer 4

它会给您一个错误，因为您的班级LibraryFront不包含getContentPane()方法。而是在框架上调用该方法。

做类似的事情：

f1.getContentPane().add(cards);