Java Reflection - NoSuchMethodException Thrown when method exists

I am trying to create a method which takes two string parameters and invokes a method call on an object. The two parameters would supply the className and methodName. Ideally I wanted to use reflection to find the object and method to then invoke the method. This is for an automation suite I manage.

public void executeMethod(String className, String methodName){
   Class object = className.getClass(); 
   Method objMethod = object.getMethod(methodName); 
   objMethod.invoke(pageObject);  
}

When I run it, I receive an error NoSuchMethodException: java.lang.String.isPageDisplayed() .

I believe my issue exists with the finding the object or something to do with the object.

If I execute the same method above as shown below, it works:

public void executeMethod(String className, String methodName){ 
    Method objMethod = knownObject.class.getMethod(methodName);
    m1.invoke(pageObject);
}

Could anyone help me figure out I am doing wrong? The method, in this case, I am trying to call is public static void method.