What is the exact meaning of instantiate in JAVA

Question

I\'am a newbie in JAVA and this came across this word called. \"A class i.e. created inside a method is called local inner class in java. If you want to invoke the methods o

Answer 1

First of all Declaring mean:

ClassName obj;

Simple meaning of instantiate is creating an object from class.

ClassName obj = new ClassName();

What is a object?

• An instance of a class. From one class we can create many instances.
• They are the basic runtime entities in in our program.
• They may also represent user-defined data types such as lists and vectors.
• Any programming problem is analyzed in terms of objects and nature of communication between them.

As a example:

//Define a reference(a variable) which can hold a `Person` obect.
Person p;
//Create a Person object(instantiate).
//new - use to allocate memory space for the new object
p = new Person();

What is a nested class?

A class that defined inside a class is called nested class. There 2 categories of nested classes.

1. inner classes
2. local classes
3. annonymous classes

Inner class:

• Inner class can only be accessed by the outer class. Not by any other class.
• Inner class is a member of outer class.
• Outer class can access inner class without importing.
• Inner class can access any attribute or a method belong to outer directly.
• Outer class cannot access directly to a inner class.

Example for a inner class:

class Outer{
   int i = 10;
   void main(){
      //instantiate inner class.
      Inner in = new Inner();
      in.show();
   }

   class Inner{
      void show(){
         System.out.print(i);
      }
   }
}

What is a local class?

Which are classes that are defined in a block.

Example:

public class{
  int i = 10;

  public main(){
     class A{
        void show(){
          System.out.println(i);
        }
     }

     //inside the method instantiate local class.
     A obj = new obj();
     obj.show();
  }
  //outside the main() -block(method)
  //inside another method instantiate local class.
  public test(){
    A obj = new A();
    obj.show();
  }
}