Methods
Methods
- The method means a block of code that executes when we call.
- It describes the behaviour or logic of an object.
Syntax:
access_modifier return_type name_Of_Method(parameters){
//body
}
Example:
public void helloWorld( int a){
//code
}
Key Points: -
- It is a Java convention that the method name should be in camelCase format (i.e. method_Name ).
- It enhances the readability and reusability of a program.
- The most common method used in Java is the main() method where the compiler starts compiling.
A parameter in Method: -
- It is the data passed through parameters that are listed after the method name and are enclosed in parentheses. e.g. printString(String msg).
Example :
package quipohouse;
public class Main
{
public static void main(String[] args)
{
String name = "Quipo House";
message(name);
}
static void message(String name) //here name is a parameter
{
System.out.println(name);
}
}
Output:
Quipo House
Arguments :
- When a parameter is passed to the method using the command line or main method is called an argument.
Example:
package quipohouse;
public class Main
{
public static void main(String[] args)
{
//arguments that passed in to the parameters
message("HELLO QUIPO HOUSE");
}
//parameters
static void message(String message)
{
System.out.println(message);
}
}
Output:
HELLO QUIPO HOUSE
Types Of Methods
1. Predefine Method:-
- It is often referred to as the built-in approach.
- This method type is already defined in the Java library or we can say that methods provided by Java itself are predefined methods.
Example:
package quipohouse;
public class Main
{
// main() method is predefined method
public static void main(String[] args)
{
String name = "QUIPO HOUSE";
message (name);
}
static void message(String name)
{
System.out.println(name);
}
}
Output:
QUIPO HOUSE
Other examples are- Math.max(), Math.min() etc.
2. User-Defined Method:-
- It is defined by the programmer or coder.
Example:
package quipohouse;
public class Main
{
public static void main(String[] args)
{
String name = "Quipo House";
message(name);
}
//Here message is user Define method
static void message(String name)
{
System.out.println(name);
}
}
Output:
Quipo House
3. Static Method:-
- When a method is defined with the keyword "Static," it signifies that it belongs to the class and not to an instance of the class.
- We can call a static and not static method without the help of an object inside the static method.
- The static method can also be called by class name or directly.
Example:
package quipohouse;
//here main method is defined with the keyword static
public class Main
{
public static void main(String[] args)
{
String name = "Quipo House";
//arguments that passed in to the parameters
message(name); //calling directly
Main.message(name); //calling by className
Main m=new Main();
m.message(name); //calling by object
}
//Here message (user Define method) also a static method
static void message(String name)
{
System.out.println(name);
}
}
Output:
QUIPO HOUSE
QUIPO HOUSE
QUIPO HOUSE
4. Instance Method: -
- It is also called a non-static method.
- In this method, we need to create an object of the class and by that object, we call the methods.
Example:
//File : Main.java
package quipohouse;
public class Main
{
public static void main(String[] args)
{
//here we are creating an object for calling the method
InstanceMethod obj = new InstanceMethod();
//arguments that passed in to the parameters
obj.Message("HELLO QUIPO HOUSE");
}
}
//File : InstanceMethod.java
package quipohouse;
public class InstanceMethod
{
public void Message(String message)
{
System.out.println(message);
}
}
Output:
HELLO QUIPO HOUSE
5. Abstract Method: -
- A method with no body is called the abstract method. It is marked as abstract.
Syntax:
abstarct void method_name();
Example:
//File : Main.java
package quipohouse;
abstract class Message
{
//abstract method which it has no body.
abstract void greets();
// concrete methods are allowed in abstract classes
void name()
{
System.out.print("QUIPO HOUSE");
}
}
// concrete class Greet
class Greet extends Message
{
// class Greet must override greets() method
void greets() //method overriding
{
System.out.print("HELLO ");
}
}
public class Main
{
public static void main(String args[])
{
Greet obj = new Greet();
obj.greets();
obj.name();
}
}
Output:
HELLO QUIPO HOUSE