Methods and Overloading methods

Methods:

• A method is a block of code which only runs when it is called.
• You can pass data, known as parameters, into a method.
• Methods are used to perform certain actions, and they are also known as functions.
• Why use methods? 
• To reuse code: define the code once, and use it many times.
• How to create method?
• A method must be declared within a class.
• It is defined with the name of the method, followed by parentheses ().
• Java provides some pre-defined methods, such as System.out.println(), but you can also create your own methods to perform certain actions.

Types of Methods:

• Static method
• Non-static method

Static method

Syntax:
static return_type method_name()
{
Statements;
}

• The void keyword, used in the above syntax, indicates that the method should not return a value.
• If you want the method to return a value, you can use a primitive data type (such as int, char, etc.) instead of void, and use the return keyword inside the method.

How to call static method?

Syntax (in same class):

methodname(argument);

Syntax (in other class):

class_name.methodname(arguments);

Full Example:
public class MyClass {
static void myMethod() {
System.out.println("I just got executed!");
}
public static void main(String[] args) {
myMethod();
}
}

Non-static methods:

Without arguments

• Syntax:

modifier return_type method_name()
{
Statments;
}

• Example:

public void sum()
{
System.out.println("sum() method");
}

With arguments:

• When a parameter is passed to the method, it is called an argument.
• Information can be passed to methods as a parameter.
• Parameters act as variables inside the method.
• Parameters are specified after the method name, inside the parentheses.
• You can add as many parameters as you want, just separate them with a comma.
• Syntax:

modifier return_type method_name(argument)
{
Statements;
}

• Example:

public void sum(int x, int y)
{
System.out.println(x+y);
}

How to call non-static method?

• To call a method in Java, write the method's name followed by two parentheses () and a semicolon.

Method Overloading in Java

• If a class has multiple methods having same name but different in parameters, it is known as Method Overloading.
• Example:
• Addition for two numbers.

public int sum(int x, int y)
{
return (x + y);
}

• Addition for three numbers.

public int sum(int x, int y, int z)
{
return (x + y + z);
}

• Advantage:
• Method overloading increases the readability of the program.
• Different ways to overload the method
• By changing the number of arguments
• By changing the data type

1. Changing no. of arguments

2. Changing data type of arguments