Built-in classes in Java

The Object class is the parent class of all the classes in java by default . In other words, it is the topmost class of java. The Object class is beneficial if you want to refer any object whose type you don’t know. Notice that parent class reference variable can refer the child class object, know as upcasting.

In Java, we can create objects with 6 different methods which are: By new keyword. By newInstance() method of Class class. By newInstance() method of constructor class.

In Java, all classes (built-in or user-defined) are (implicitly) subclasses of Object . Using an array of Object in the List class allows any kind of Object (an instance of any class) to be stored in the list. However, primitive types (int, char, etc) cannot be stored in the list.

JavaScript also has four built-in objects: Array, Date, Math, and String .