Switching JPanels within a JFrame
Question:
I'm new to Java components and having trouble switching JPanels inside a JFrame. When I call gameOn(), the Frame surface becomes blank without displaying the game panel. How can I fix this?
Answer:
Instead of adding and removing components, it's recommended to use a CardLayout. Here's how:
-
Create a CardLayout object and a JPanel using it:
<code class="java">CardLayout cardLayout = new CardLayout(); JPanel mainPanel = new JPanel(cardLayout);</code>
-
Add the menu and game panels to mainPanel:
<code class="java">MenuPanel menu = new MenuPanel(); GamePanel game = new GamePanel(); mainPanel.add(menu, "menu"); mainPanel.add(game, "game");</code>
-
In the gameOn() method, simply show the game panel using cardLayout without adding or removing any components:
<code class="java">public void gameOn() { cardLayout.show(mainPanel, "game"); }</code>
- When gameOn() is called, the menu panel will be hidden behind the game panel.
Example:
<code class="java">import java.awt.BorderLayout; import java.awt.CardLayout; import java.awt.Color; import java.awt.Dimension; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.SwingUtilities; class GameFrame extends JFrame implements ActionListener { public static void main(String[] args) { SwingUtilities.invokeLater(() -> new GameFrame().setVisible(true)); } private CardLayout cardLayout; private JPanel mainPanel; private MenuPanel menuPanel; private GamePanel gamePanel; public GameFrame() { cardLayout = new CardLayout(); mainPanel = new JPanel(cardLayout); menuPanel = new MenuPanel(); mainPanel.add(menuPanel, "menu"); gamePanel = new GamePanel(); mainPanel.add(gamePanel, "game"); JButton goGameButton = new JButton("Go to Game"); goGameButton.addActionListener(this); add(mainPanel); add(goGameButton, BorderLayout.SOUTH); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); pack(); setLocationRelativeTo(null); } @Override public void actionPerformed(ActionEvent e) { cardLayout.show(mainPanel, "game"); } } class MenuPanel extends JPanel { public MenuPanel() { setBackground(Color.GREEN); add(new JLabel("Menu")); } @Override public Dimension getPreferredSize() { return new Dimension(300, 300); } } class GamePanel extends JPanel { public GamePanel() { setBackground(Color.BLUE); add(new JLabel("Game")); } @Override public Dimension getPreferredSize() { return new Dimension(300, 300); } }</code>
The above is the detailed content of How to Switch JPanels within a JFrame using CardLayout?. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undress AI Tool
Undress images for free

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

The difference between HashMap and Hashtable is mainly reflected in thread safety, null value support and performance. 1. In terms of thread safety, Hashtable is thread-safe, and its methods are mostly synchronous methods, while HashMap does not perform synchronization processing, which is not thread-safe; 2. In terms of null value support, HashMap allows one null key and multiple null values, while Hashtable does not allow null keys or values, otherwise a NullPointerException will be thrown; 3. In terms of performance, HashMap is more efficient because there is no synchronization mechanism, and Hashtable has a low locking performance for each operation. It is recommended to use ConcurrentHashMap instead.

StaticmethodsininterfaceswereintroducedinJava8toallowutilityfunctionswithintheinterfaceitself.BeforeJava8,suchfunctionsrequiredseparatehelperclasses,leadingtodisorganizedcode.Now,staticmethodsprovidethreekeybenefits:1)theyenableutilitymethodsdirectly

The JIT compiler optimizes code through four methods: method inline, hot spot detection and compilation, type speculation and devirtualization, and redundant operation elimination. 1. Method inline reduces call overhead and inserts frequently called small methods directly into the call; 2. Hot spot detection and high-frequency code execution and centrally optimize it to save resources; 3. Type speculation collects runtime type information to achieve devirtualization calls, improving efficiency; 4. Redundant operations eliminate useless calculations and inspections based on operational data deletion, enhancing performance.

Instance initialization blocks are used in Java to run initialization logic when creating objects, which are executed before the constructor. It is suitable for scenarios where multiple constructors share initialization code, complex field initialization, or anonymous class initialization scenarios. Unlike static initialization blocks, it is executed every time it is instantiated, while static initialization blocks only run once when the class is loaded.

Java uses wrapper classes because basic data types cannot directly participate in object-oriented operations, and object forms are often required in actual needs; 1. Collection classes can only store objects, such as Lists use automatic boxing to store numerical values; 2. Generics do not support basic types, and packaging classes must be used as type parameters; 3. Packaging classes can represent null values ??to distinguish unset or missing data; 4. Packaging classes provide practical methods such as string conversion to facilitate data parsing and processing, so in scenarios where these characteristics are needed, packaging classes are indispensable.

Factory mode is used to encapsulate object creation logic, making the code more flexible, easy to maintain, and loosely coupled. The core answer is: by centrally managing object creation logic, hiding implementation details, and supporting the creation of multiple related objects. The specific description is as follows: the factory mode handes object creation to a special factory class or method for processing, avoiding the use of newClass() directly; it is suitable for scenarios where multiple types of related objects are created, creation logic may change, and implementation details need to be hidden; for example, in the payment processor, Stripe, PayPal and other instances are created through factories; its implementation includes the object returned by the factory class based on input parameters, and all objects realize a common interface; common variants include simple factories, factory methods and abstract factories, which are suitable for different complexities.

There are two types of conversion: implicit and explicit. 1. Implicit conversion occurs automatically, such as converting int to double; 2. Explicit conversion requires manual operation, such as using (int)myDouble. A case where type conversion is required includes processing user input, mathematical operations, or passing different types of values ??between functions. Issues that need to be noted are: turning floating-point numbers into integers will truncate the fractional part, turning large types into small types may lead to data loss, and some languages ??do not allow direct conversion of specific types. A proper understanding of language conversion rules helps avoid errors.

InJava,thefinalkeywordpreventsavariable’svaluefrombeingchangedafterassignment,butitsbehaviordiffersforprimitivesandobjectreferences.Forprimitivevariables,finalmakesthevalueconstant,asinfinalintMAX_SPEED=100;wherereassignmentcausesanerror.Forobjectref
