public static <T> Constructor<T> findConstructor(Class<T> cls, boolean canFixAccess)
throws IllegalArgumentException {
try {
Constructor<T> ctor = cls.getDeclaredConstructor();
if (canFixAccess) {
checkAndFixAccess(ctor);
} else {
// Has to be public...
if (!Modifier.isPublic(ctor.getModifiers())) {
throw new IllegalArgumentException(
"Default constructor for "
+ cls.getName()
+ " is not accessible (non-public?): not allowed to try modify access via Reflection: can not instantiate type");
}
}
return ctor;
} catch (NoSuchMethodException e) {;
} catch (Exception e) {
ClassUtil.unwrapAndThrowAsIAE(
e,
"Failed to find default constructor of class "
+ cls.getName()
+ ", problem: "
+ e.getMessage());
}
return null;
}
/**
* Method that can be called to try to create an instantiate of specified type. Instantiation is
* done using default no-argument constructor.
*
* @param canFixAccess Whether it is possible to try to change access rights of the default
* constructor (in case it is not publicly accessible) or not.
* @throws IllegalArgumentException If instantiation fails for any reason; except for cases where
* constructor throws an unchecked exception (which will be passed as is)
*/
public static <T> T createInstance(Class<T> cls, boolean canFixAccess)
throws IllegalArgumentException {
Constructor<T> ctor = findConstructor(cls, canFixAccess);
if (ctor == null) {
throw new IllegalArgumentException(
"Class " + cls.getName() + " has no default (no arg) constructor");
}
try {
return ctor.newInstance();
} catch (Exception e) {
ClassUtil.unwrapAndThrowAsIAE(
e, "Failed to instantiate class " + cls.getName() + ", problem: " + e.getMessage());
return null;
}
}
