如何获取显示器分辨率并设置到DesktopLauncher？伪全屏代码报错求助

Hey there, let's tackle your two questions one by one:

Since you're working with a LibGDX DesktopLauncher, there are two reliable ways to grab the monitor's native resolution and apply it to your configuration:

Method 1: Use LibGDX's Built-in DisplayMode #

This is the most straightforward approach for LibGDX projects:

public class DesktopLauncher {
    public static void main (String[] arg) {
        // Initialize the config object first
        LwjglApplicationConfiguration config = new LwjglApplicationConfiguration();
        
        // Get the primary monitor's display mode
        DisplayMode displayMode = LwjglApplicationConfiguration.getDisplayMode();
        
        // Set config dimensions to match the monitor
        config.width = displayMode.width;
        config.height = displayMode.height;
        
        // Launch your game with the updated config
        new LwjglApplication(new YourGameClass(), config);
    }
}

Method 2: Use AWT Toolkit (For Multi-Monitor Flexibility) #

If you need to target a specific monitor or want a more cross-desktop compatible way, use AWT's Toolkit:

import java.awt.Toolkit;

public class DesktopLauncher {
    public static void main (String[] arg) {
        LwjglApplicationConfiguration config = new LwjglApplicationConfiguration();
        
        // Fetch screen resolution via AWT
        java.awt.Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        config.width = (int) screenSize.getWidth();
        config.height = (int) screenSize.getHeight();
        
        new LwjglApplication(new YourGameClass(), config);
    }
}

Note: LibGDX's desktop project includes AWT dependencies by default, so this should work out of the box.

That NullPointerException at line 13 of your DesktopLauncher means you're trying to access a method/property on an object that hasn't been initialized (it's null). Let's break down the likely causes and fixes:

First, Let's Confirm the Correct Borderless Fullscreen Setup #

Terraria's "pseudo-fullscreen" is just a borderless window that fills the entire screen. Here's the proper way to implement it in LibGDX:

public class DesktopLauncher {
    public static void main (String[] arg) {
        LwjglApplicationConfiguration config = new LwjglApplicationConfiguration();
        
        // Get screen resolution (with null check to avoid NPE!)
        DisplayMode displayMode = LwjglApplicationConfiguration.getDisplayMode();
        if (displayMode != null) {
            config.width = displayMode.width;
            config.height = displayMode.height;
        } else {
            // Fallback to a default resolution if display mode can't be fetched
            config.width = 1920;
            config.height = 1080;
        }
        
        // Enable borderless window (this is the key for pseudo-fullscreen)
        config.borderless = true;
        // Optional: Prevent window resizing
        config.resizable = false;
        
        // Make sure your game instance is properly initialized!
        new LwjglApplication(new MMGame(), config);
    }
}

Likely Causes of the NullPointerException #

1. Uninitialized config Object
   If line 13 is something like config.width = ... but you forgot to create the config with new LwjglApplicationConfiguration(), that'll throw an NPE. Double-check that you've initialized config before using it.

2. Null DisplayMode
   In rare cases, LwjglApplicationConfiguration.getDisplayMode() might return null (e.g., headless environments, though that's unlikely for a desktop game). Adding a null check like in the example above will prevent this.

3. Null Game Instance
   If line 13 is the new LwjglApplication(...) call, make sure you're passing a valid instance of your game class (not null). For example, new LwjglApplication(null, config) would trigger an NPE.

Debugging Step #

To pinpoint exactly what's null, add print statements to your main method:

public static void main (String[] arg) {
    System.out.println("Launcher starting...");
    LwjglApplicationConfiguration config = new LwjglApplicationConfiguration();
    System.out.println("Config initialized: " + (config != null));
    
    DisplayMode displayMode = LwjglApplicationConfiguration.getDisplayMode();
    System.out.println("DisplayMode: " + displayMode);
    
    if (displayMode != null) {
        System.out.println("Display width: " + displayMode.width);
    }
    
    // Rest of your code...
}

Run the game again, and the console output will tell you which object is null.

内容的提问来源于stack exchange，提问作者leonidsah