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Documentation Index

Fetch the complete documentation index at: https://mintlify.com/pojavlauncherteam/pojavlauncher/llms.txt

Use this file to discover all available pages before exploring further.

PojavLauncher runs Minecraft through a full Java runtime bundled on your device, which means you have real control over the JVM that launches the game. The Java settings screen lets you install and switch between multiple Java runtimes, pass arbitrary JVM flags, cap the heap size, and toggle the security sandbox. Getting these values right is one of the most impactful things you can do for stability and performance.

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Runtime Manager

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install_jre
action (button)
Opens the Multi-Runtime Manager dialog, where you can:
  • View all currently installed Java runtimes
  • Install a new runtime from a .tar.xz archive (via the system file picker)
  • Set which runtime is used as the default
  • Remove runtimes you no longer need
Minecraft versions have different Java requirements — Java 8 for 1.16 and below, Java 17 for 1.17–1.20, and Java 21 for 1.21+. Use this manager to keep multiple runtimes installed side-by-side.See Multi-Runtime for installation instructions.
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defaultRuntime
string
default:"first available runtime"
The name of the Java runtime that will be used when launching any profile that does not specify an explicit runtime. The value is set automatically to the first entry returned by the runtime manager when no preference has been saved yet.

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Memory

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allocation
integer (MB)
default:"auto"
Amount of RAM in megabytes allocated to the Minecraft JVM heap (-Xmx). The seekbar is capped at a device-safe maximum calculated at runtime to ensure the Android OS itself retains enough memory to operate.Auto allocation logic — findBestRAMAllocation() picks a default based on total device RAM:
Device RAMDefault Allocation
< 1 024 MB296 MB
< 1 536 MB448 MB
< 2 048 MB656 MB
Any 32-bit device696 MB (hard cap)
< 3 064 MB936 MB
< 4 096 MB1 144 MB
< 6 144 MB1 536 MB
≥ 6 144 MB (64-bit)2 048 MB
Maximum seekbar cap (from LauncherPreferenceJavaFragment):
  • 32-bit device or < 2 GB RAM → min(1024, deviceRam) MB
  • Otherwise → deviceRam − 800 MB (< 3 064 MB) or deviceRam − 1024 MB (≥ 3 064 MB)
Allocating too little RAM causes Minecraft to lag and crash with OutOfMemoryError. Allocating too much prevents Android from running background processes and may trigger the OS memory killer, forcibly closing the game.

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Custom JVM Arguments

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javaArgs
string
default:"\"\""
A space-separated list of additional arguments passed directly to the JVM before the Minecraft main class. Useful for enabling garbage-collector tuning, system properties, and modding framework flags.Common examples:
# Set initial heap size to 256 MB (avoids slow GC ramp-up)
-Xms256m

# Use the G1 garbage collector (recommended for Minecraft)
-XX:+UseG1GC

# Bypass Forge's invalid-certificate check (older Forge versions)
-Dfml.ignoreInvalidMinecraftCertificates=true

# Disable aggressive OptiFine memory management
-Doptifine.DynamicResources=false
Any argument beginning with -Dorg.lwjgl.opengl.libname= is automatically stripped (purged) from this field every time preferences are loaded. PojavLauncher manages the LWJGL native library path internally; overriding it will break rendering.
On devices with ≥ 4 GB RAM, combining -Xms256m -XX:+UseG1GC -XX:MaxGCPauseMillis=100 often produces smoother frame pacing by reducing garbage-collection pause spikes.

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Security

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java_sandbox
boolean
default:"true"
Enables a lightweight Java security manager that restricts what Minecraft mods can do at the OS level — for example, preventing them from spawning arbitrary subprocesses or accessing files outside the game directory.
Disabling the sandbox removes these restrictions. Only turn this off if a specific mod or modloader requires it and you trust the source of those mods completely.

Multi-Runtime Manager

Step-by-step guide to installing, switching, and removing Java runtimes.

Experimental Settings

Additional power-user options including download mirrors and manifest verification.

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