Module 2: Introduction to OOP

In manufacturing, a blueprint describes a device from which many physical devices are constructed.
In Java, a class is nothing but a blueprint or a template for creating different objects which defines its properties and behaviors. Java class objects exhibit the properties and behaviors defined by its class. A class can contain fields and methods to describe the behavior of an object.

Declaring Java Technology Classes

Basic syntax of a Java class:

<modifiers> class <class_name> {
  [<attribute_declarations>]
  [<constructor_declarations>]
  [<method_declarations>]
}

Methods are nothing but members of a class that provide a service for an object or perform some business logic. Java fields and member functions names are case sensitive. Current states of a class’s corresponding object are stored in the object’s instance variables. Methods define the operations that can be performed in java programming.


Basic syntax of an attribute:

<modifiers> <type> <name>;


Basic syntax of a method:
<modifiers> <return_type> <name>
([<argument_list>]) {
[<statements>]
}

Examples:

public class Dog {
  private int weight;
  public int getWeight() {
    return weight;
  }
  public void setWeight(int newWeight) {
    weight = newWeight;
  }
}


Example of class definition


public class Foo {
  private int x;
  private float y = 10000.0F;
  private String name = "Motel";
}