Method in Java programming language with example
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Method in Java programming language with example
Method in Java programming language with example
In this tutorial, We will learn about Method in Java programming language with an example.
Method in Java
The method is an important concept in Object-oriented programming languages(Oop). In the Java programming language, a method is a segment of code referred to by a name that does a particular task. A Java method has a collection of statements that are grouped together to perform a particular operation.
A particular method can contain two section
method header – method header should be two factor
- return type variable – void, int, float, double etc
- method name – user can define(User define method)
method body – method body is enclosed using braces (curly brackets)and it has a group of statements to perform a particular task
Two type methods available in Java
- Pre-defined method – Standard Library Methods
- User-defined method
Pre-defined method – Standard Library Methods
These methods are in-build methods, already defined in the Java Library file. They are ready to be used at any time.
For example
- Math function in Java – sqrt(), log()
- String function in Java – str.length()
User defined method in Java
Inside the class, you can define a method to perform a particular task according to your purpose. It is known as a user-defined method.
Declaration
Syntax of method
modifier return_type method_name(list of parameter){
method body
}
Here
modifier – public private protected and static
return type – it is a section of the method used to denote the returned value.
All data types except void are functioning return type.
method name(user define)– Some of the rules should be applied to the method name.
Parenthesis() – we can pass a list of parameter separated with commas inside the Parenthesis().
Example of method
public static int get_Sum(int a, int b){ //parameter is an optional part in method
statement(s)
//method body
}
Here,
public, static – access modifier
int – a return type which may return a value to the main method other than when the void is used.
get_Sum – method name – it is used to identify a particular method
int a, int b – list of parameter
If we use no parameter or empty argument, it is known as the default parameter.
The method body( braces(curly brackets)) includes the codes including the statements.
Java has three type of method
- The dumb method– Does the same thing every time.
void add(){
int x=5;
int y=7;
System.out.println(a+b);
}
Program 1
//Example for dumb method
public class dumbmetod1{
public static void main(String args[]){ //main methid
add();//call the method inside the main method
}
public static void add(){
int a=25,b=35; //user define method
System.out.println("Total is :"+(a+b));
}
}
When the above code is executed, it produces the following results:
Total is : 60
2. Clever method –
Ask for an input value
Eg - void add(int a, int b){
System.out.println(a+b);
}
Program 2
//Example for clever method
public class Clever_method1{
public static void main(String args[]){
add(40,25);//call the method inside the main method
}//with argument
public static void add(int a, int b){//parameter
System.out.println("Total is :"+(a+b));
System.out.println("Different is :"+(a-b));
System.out.println("Multiplication is :"+(a*b));
System.out.println("Division is :"+(a/b));
}
}
When the above code is executed, it produces the following results:
Total is :65 Different is :15 Multiplication is : 1000 Division is :1
2. Smart method –
Ask for input value and returns the result to the main method
Eg - void add(int a, int b)
{
int c=a+b;
return c;
}
Program 3
//Example for smart method
public class Smart_method1{
public static void main(String args[]){
System.out.println("Total is :"+add(65,35));
}
public static int add(int a, int b){
int sum=a+b; //user defined method with parameter
return sum;//return value to main method
}
}
When the above code is executed, it produces the following results:
Total is :100
How to call a method
If you defined a method for your significant task, you can use this method on your program
You have to call the method, like this
method_Mame(); my_method();
It is possible only if you have already defined a method
Example for calling the method in the program
public class Class_name{
public static void main(String args[]){ //main method
my_Metod();//call the method inside the main method
}
public static void my_Method(){
statement(s) //method body
}
}
When we call the method, How method works?
1 – In java language, firstly, you should call your method inside the main method.
2 – When Java program codes are being executed, it meets the methods inside the main methods and executes the declaring of the method through the method name.
3 – Then the executed results from the method returns to the main method.
Program 1
public class Method_example{
public static void my_Method(){//user define method
System.out.println("This is the property of my method:");
}//end of user define method
public static void main(String args[]){ //main method
System.out.println("call the method from inside the main method:");
my_Method();//call the method inside the main method
}//end of method
}
When the above code is executed, it produces the following results:
call the method from inside the main method This is the property of my method:
Program 2
When we declare two separate classes how to call a method from one to another
class Class_main1{//class_one
public static void main(String args[]){
Class_U_method obj=new Class_U_method();
//create object for class_U_method
obj.my_method();//calling the metod
//method was executed successfully here
}
}
class Class_U_method{//class_two
public void my_method(){ //user defined method as public
System.out.println("Display statement from inside user defined method");
}//method statements here
}
When the above code is executed, it produces the following results:
Display statement from inside user defined method
Java Method and return value
A Java method can have either empty or more parameter and they return a value.
Let’s see a very simple example to understand how to Java method returns value during the addition of two numbers
Program 1
class calc1{
public static void main(String args[]){
System.out.println(add_Num());//Call the method
}
static int add_Num(){//Java method with Zero parameter
return (5+10);//return statement
//return value to main method
}
}
return is a Java keyword used to return value from a method.
When the above code is executed, it produces the following results:
15
Just simple modification at the above program for easy understanding
class calc2{
public static void main(String args[]){
int result=add_Num();//assign the output to another variable
System.out.println(result);//display result
}
static int add_Num(){
return (5+10);
}
}
When the above code is executed, it produces the following results:
15
Same output
Now we will try to clearly understand return statement – How it works
According to the example, this method always returns the same value (added value of 15) to the main method.
Java Method and return value with the argument
Same thing(return value) but with the addition of simple modification of the above program with the argument
Program 1
class calc3{
public static void main(String args[]){
int result=add_Num(5,10);//argument
System.out.println(result);
}//main metod
static int add_Num(int a,int b){//parameter
return (a+b);
//user defined method
}
}
When the above code is executed, it produces the following results:
15
Let’s try to understand how the above program works
Multiple methods and multiple argument inside a class
Program 1
class calc4{
public static void main(String args[]){
System.out.println("sum of 20 + 10 ="+add_Num(20,10));//argument 1
System.out.println("Different of 20 - 10 ="+sub_Num(20,10)); //argument 2
System.out.println("multiply of 20 * 10 ="+mul_Num(20,10)); //argument 3
System.out.println("division of 20 / 10 ="+div_Num(20,10)); //argument 4
}
static int add_Num(int a,int b){//parameter 1
return (a+b);
}
static int sub_Num(int a,int b){//parameter 2
return (a-b);
}
static int mul_Num(int a,int b){//parameter 3
return (a*b);
}
static int div_Num(int a,int b){//parameter 4
return (a/b);
}
}
When the above code is executed, it produces the following results:
sum of 20 + 10 = 20 Different of 20 - 10 = 10 multiply of 20 * 10 = 200 division of 20 / 10 = 2
Calculate the total value of 1 t0 100:
Program
class calc5{
public static void main(String args[]){
add_Num();//method call
}
static int add_Num(){
int sum=0;
//calculate 1 to 100 positive integer numbers
for(int i=1; i<=100; i++){
sum=sum+i;
}
System.out.println("Total value is :"+sum);
return (sum);
}
}
When the above code is executed, it produces the following results:
Total value is :5050
Advantages of the method in Java
- A method is created using a set of statements for a specific task. So it can be used as you choose.
- Code re-usability – method can be created only once and used multiple time.
- As the method is a group of statements, the bulk of methods can be used to create programmes. It is readable, understandable and debugging is very easy.
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