How can I check if a method is static using reflection?
I want to discover at run-time ONLY the static Methods of a class, how can I do this? Or, how to differentiate between static and non-static methods.
Asked by: Paul654 | Posted: 28-01-2022
Answer 1
Use Modifier.isStatic(method.getModifiers()).
/**
* Returns the public static methods of a class or interface,
* including those declared in super classes and interfaces.
*/
public static List<Method> getStaticMethods(Class<?> clazz) {
List<Method> methods = new ArrayList<Method>();
for (Method method : clazz.getMethods()) {
if (Modifier.isStatic(method.getModifiers())) {
methods.add(method);
}
}
return Collections.unmodifiableList(methods);
}
Note: This method is actually dangerous from a security standpoint. Class.getMethods "bypass[es] SecurityManager checks depending on the immediate caller's class loader" (see section 6 of the Java secure coding guidelines).
Disclaimer: Not tested or even compiled.
Note Modifier should be used with care. Flags represented as ints are not type safe. A common mistake is to test a modifier flag on a type of reflection object that it does not apply to. It may be the case that a flag in the same position is set to denote some other information.
Answer 2
You can get the static methods like this:
for (Method m : MyClass.class.getMethods()) {
if (Modifier.isStatic(m.getModifiers()))
System.out.println("Static Method: " + m.getName());
}
Answer 3
To flesh out the previous (correct) answer, here is a full code snippet which does what you want (exceptions ignored):
public Method[] getStatics(Class<?> c) {
Method[] all = c.getDeclaredMethods()
List<Method> back = new ArrayList<Method>();
for (Method m : all) {
if (Modifier.isStatic(m.getModifiers())) {
back.add(m);
}
}
return back.toArray(new Method[back.size()]);
}
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