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Method Removal & Modification

Mixin Helper can surgically remove or neutralize methods from target classes after all mixins have been applied. This is useful when blacklisting an entire mixin is too aggressive, but a specific injected method is causing problems.

Actions​

nop (No Operation)​

Replaces the method body with a type-appropriate default return:

  • void methods → empty body
  • boolean methods → return false
  • Numeric methods → return 0
  • Object methods → return null

The method signature remains intact, so other code that calls it will not crash — it simply does nothing.

{
  "targetClass": "net.minecraft.world.level.Level",
  "method": "problematicMethod",
  "action": "nop"
}

remove​

Deletes the method entirely from the class bytecode.

{
  "targetClass": "net.minecraft.world.level.Level",
  "method": "problematicMethod",
  "action": "remove"
}
warning

The remove action will cause a NoSuchMethodError if any code attempts to call the removed method. Use nop unless you are certain the method is never called directly.

Method Matching​

Three ways to identify the method to target.

By Exact Name​

Match a method by its name. If multiple methods share the same name (overloads), all matching methods are affected.

{
  "targetClass": "net.minecraft.world.level.Level",
  "method": "tickPlayers",
  "action": "nop"
}

By Name and Descriptor​

Add a descriptor to match a specific overload. The descriptor follows Java bytecode format.

{
  "targetClass": "net.minecraft.world.level.Level",
  "method": "tickPlayers",
  "descriptor": "()V",
  "action": "nop"
}

Common Descriptors​

DescriptorMeaning
()VNo parameters, returns void
(I)VTakes an int, returns void
(Z)ZTakes a boolean, returns boolean
(Ljava/lang/String;)VTakes a String, returns void
(II)ITakes two ints, returns int

By Regex Pattern​

Match multiple methods using a regular expression on the method name.

{
  "targetClass": "net.minecraft.client.gui.screens.Screen",
  "methodPattern": "render.*",
  "action": "nop"
}

This matches any method whose name starts with render — e.g., render, renderBackground, renderTooltip.

tip

Use methodPattern when a mod injects several related methods that you want to disable at once.

Multiple Rules​

You can define multiple rules. They are applied in order:

"methodRemovals": {
  "rules": [
    {
      "targetClass": "net.minecraft.world.level.Level",
      "method": "tickPlayers",
      "action": "nop"
    },
    {
      "targetClass": "net.minecraft.client.gui.screens.Screen",
      "methodPattern": "customRender.*",
      "action": "remove"
    }
  ]
}

When to Use Method Removal​

ScenarioRecommended Action
Injected method causes a crashnop — safest fix
Injected method causes visual glitchesnop — method still callable
Method is confirmed unused by any coderemove — cleanest option
Multiple related injected methods to disablemethodPattern + nop

Method Removal vs Blacklisting​

  • Blacklisting prevents a mixin from loading at all — none of its changes apply
  • Method removal lets the mixin apply normally, then strips a specific method afterward

Use method removal when a mixin does several things and you only want to undo one of them.

Verifying Method Removal​

Enable debug logging to confirm your rules are being applied:

"debug": {
  "logMethodRemovals": true
}

Check the game log for confirmation:

[MixinHelper] Nop'd method: tickPlayers()V in net.minecraft.world.level.Level
[MixinHelper] Removed method: customRenderOverlay in net.minecraft.client.gui.screens.Screen

Next Steps​