Calling functions with variables

Processing Beginners
9

Interesting, thanks!

If we’re going to go into more detail, it appears that getMethod(name) isn’t O(1) after all and also just searches through an array of methods:

http://hg.openjdk.java.net/jdk8/jdk8/jdk/file/687fd7c7986d/src/share/classes/java/lang/Class.java

// The following code is simplified to only show the parts that matter

public Method getMethod(String name, Class<?>[] parameterTypes) {
  // searchMethods(...) is O(n)
  return searchMethods(privateGetDeclaredMethods(true), name, parameterTypes);
}

private static Method searchMethods(Method[] methods, String name, Class<?>[] parameterTypes) {
  Method res = null;
  String internedName = name.intern();
  
  // O(n) here:
  for (int i = 0; i < methods.length; i++) {
    Method m = methods[i];
    if (m.getName() == internedName
      && arrayContentsEq(parameterTypes, m.getParameterTypes())
      && (res == null
      || res.getReturnType().isAssignableFrom(m.getReturnType())))
      res = m;
  }

  return (res == null ? res : getReflectionFactory().copyMethod(res));
}


private Method[] privateGetDeclaredMethods(boolean publicOnly) {
  return // an array of methods stored in a field, so O(1)
}

Also, getClass().getDeclaredMethods() apparently just returns the methods added by the current class, not the ones of its superclass, so in case of the example I gave above it would be setup(), draw(), getMethodsStartingWith(String), mousePressed(), scene1(), scene2() and scene3(), which always makes that approach faster, I guess.

The object-oriented approach by @noahbuddy is still the one that makes the most sense though, but I figured it would be interesting to go further into this.

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