Methods in Java

● Same as functions in programming language
● None of the methods can be declared outside the class.

● Why use methods?

– To make code reusable
– To parametrise the code
– For top-down programming
– To simplify the code

● Two types of methods
– Instance methods
– Class methods

● Instance methods are used to access/manipulate the instance variables but can also access access class variables.

● Class methods can access / manipulate class variables but cannot access instance variable unless and until they use an object for that purpose.

Method Overloading in Java

● If a class have multiple methods by same name but different parameters, it is known as Method Overloading.

● If we have to perform only one operation, having same name of the methods increases the readability of the program.

● Advantage of method overloading? – Method overloading increases the readability of the program.

● There are three ways to overload the method in java
– By changing number of arguments
– By changing the data type
– By changing the sequence

Access Specifiers in Java

● There are two types of modifiers in java: access modifiers and nonaccess modifiers.
● The access modifiers in java specifies accessibility (scope) of a data member, method, constructor or class.

● There are 4 types of java access modifiers:
–    Private
–    Default
–    Protected
–    Public

● There are many non-access modifiers such as static, abstract, synchronized, native, volatile, transient etc.

1).Private access modifier

● The private access modifier is accessible only within class.
● Role of Private Constructor – If you make any class constructor private, you cannot create the instance of that class from outside the class.
● A class cannot be private or protected except nested class.

2).Default access modifier

● If you don't use any modifier, it is treated as default by default
● The default modifier is accessible only within package.

3).Protected access modifier

● The protected access modifier is accessible within package and outside the package but through inheritance only.
● The protected access modifier can be applied on the data member, method and constructor.
● It can't be applied on the class.