The answer to this is related to the idea of inheritance in general - the idea of inheritance is that you define a common set of behaviors, that apply to all subclasses. Anything defined in the "Object" class is available to all classes you create. Look in the documentation for the description of the "Object" class, to see what methods are available in all Java classes.
No. never. An instance method cannot replace a class method because: Instance Methods - are normal methods that are linked to a class object instance Class Methods - are static methods that are not linked to any class object. These methods are not interchangeable and will create too many issues if we try to use one in place of the other.
The Object class, in the java.lang package, sits at the top of the class hierarchy tree. Every class is a descendant, direct or indirect, of the Object class. Every class you use or write inherits the instance methods of Object. You need not use any of these methods, but, if you choose to do so, you may need to override them with code that is specific to your class
Object is an instance of a class. Example: In general, animal is a class where as, tiger is an object.
StringBuffer is java class available in java.lang package which provides mutable String object where String is immutable class. The methods of this class like reverse(), append(),insert() gives facility to insert data of the same object.
Instance methods can be called by the object of a Class whereas static method are called by the Class. When objects of a Class are created, they have their own copy of instance methods and variables, stored in different memory locations. Static Methods and variables are shared among all the objects of the Class, stored in one fixed location in memory.Static methods cannotaccess instance variables or instance methods directly-they must use an object reference. Also, class methods cannot use the this keyword as there is no instance for this to refer to.
Though implementing Runnable interface is better approach than inheriting from Thread class but there are certain methods available in Thread class like join,sleep or yield which does not available in Runnable interface and programmer can not use them unless he has object of Thread class. This is why we should have Thread class Object. Rupesh Raghani
A Class. It encapsulates its variables and methods into it.
Class methods are the member functions that act upon member variables. An object is an instance of a class. C does not support object-oriented programming, but C++ does.
Instance variableA variable, part of an Object. These might better be called perObject variables since each instantiated object of this class will have its own private copy of this variable. They are allocated when the object is allocated via new. Static methods may not access the instance variables of their class (or any other class for that matter), other that via some object reference, e.g. anObject.someField. Static methods may even access private instance variables in their class via some object reference.
Type casting exists to allow the use of base class or base interface reference but yet if you know that the object in hand is aspecific derived class, you can typecast and access methods available only in the derived class.
It is a static class; meaning that all the methods can be accessed directly from the class name, without instantiating an object.It is a static class; meaning that all the methods can be accessed directly from the class name, without instantiating an object.It is a static class; meaning that all the methods can be accessed directly from the class name, without instantiating an object.It is a static class; meaning that all the methods can be accessed directly from the class name, without instantiating an object.