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Methods Concept in Java
Syntax of Method-
The basic Syntax of method is given below
Types Of Method
There are two types of methods in java i.e
1. Instance method
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QA acharya
Tags: Methods in java , Types of method in java , syntax of method , method calling in java , Declaration of method in java , How to call method , rules for declaring method in java .
- Inside the classes it is not possible to write the business logics directly, so inside the class declares the
- method inside that method writes the logics of the application.
Methods In java - Methods are used to write the business logics of the application.
- Inside the class it is possible to declare n number of instance &static methods based on the developer requirement.
- Method will improve the reusability of the code and we can optimize the code.
- Whether it is an instance method or static method the methods are used to provide business logics of the project.
Coding
convention For Method :
Naming convention for method given below
method name starts with lower case letter and every inner word starts withuppercase letter (mixed case).
Naming convention for method given below
method name starts with lower case letter and every inner word starts withuppercase letter (mixed case).
ex: post() ,
charAt() , toUpperCase() , compareToIgnoreCase()……etc
Public
void method1() //Mehod Without parameter
Private int
method2(int a,int b) //Method With Parameter
Private String method3(char ch)throws Exception //Method with Exception
Private String method3(char ch)throws Exception //Method with Exception
Modifiers list return Type Methodname (parameters list) throws Exception
Private String mehod1 (char ch) throws Exception
Method name
---> functionality name
Parameter-list
---> input to functionality
Modifiers-list
---> represent access permissions.
Return-type
---> functionality return value
Throws
Exception ---> representing exception handling
In Java Every method contains three parts.
1. Method declaration
2. Method implementation (logic)
3. Method calling
Example :
Class Test
{
void m1() //method declaration
{
System.out.println("java methods "); //method implementation
}
public static void main(String[] args) {
Test t = new Test();
t.m1(); // method calling
}
}
Output: Java method
In Java Every method contains three parts.
1. Method declaration
2. Method implementation (logic)
3. Method calling
Example :
Class Test
{
void m1() //method declaration
{
System.out.println("java methods "); //method implementation
}
public static void main(String[] args) {
Test t = new Test();
t.m1(); // method calling
}
}
Output: Java method
Method
Signature: Method-name & parameters list is called method signature.
Syntax:
Method-name(parameter-list)
ex: m1(int
a)
m2(int a,int
b)
Method Calling in java
Question :How to Call a Method in java?
Answer: In Java to call a method , first we have to write the method's name followed by two parentheses () and a semicolon;
In the following example, myfirstMethod() is used to print a text , when method is called
Example
public class Test
{
static void myFirstMethod() //Method Declaration
{
System.out.println("java method ");
}
public static void main(String[] args) {
Test t = new Test();
t. myFirstMethod(); //Method Calling
}
}
Output :"java method"
Method Calling in java
Question :How to Call a Method in java?
Answer: In Java to call a method , first we have to write the method's name followed by two parentheses () and a semicolon;
In the following example, myfirstMethod() is used to print a text , when method is called
Example
public class Test
{
static void myFirstMethod() //Method Declaration
{
System.out.println("java method ");
}
public static void main(String[] args) {
Test t = new Test();
t. myFirstMethod(); //Method Calling
}
}
Output :"java method"
There are two types of methods in java i.e
1. Instance method
2. Static
method
Java Instance methods:
Java Static methods:
static method is a method that can be called and executed without creating an object. In general, static methods are used to create instance methods.
Static method can be invoked directly via class name i.e.; we don't have to create an object for a class in order to initiate static method.
Rules and Regulation For Method-
#Rule-1 it is possible to provide Objects as a parameters(in real time project).
#Rule-2 Java methods return type is mandatory, otherwise the compilation will generate error
#Rule-3 Inside the class it is not possible to declare more than one method with same
#Rule-4 Declaring the class inside another class is called inner classes, java supports inner classes.
#Rule-7 coming Soon..
Hope !! Above Tutorial of java methods and types of java method helpful for you ..Java Instance methods:
Java Static methods:
static method is a method that can be called and executed without creating an object. In general, static methods are used to create instance methods.
Static method can be invoked directly via class name i.e.; we don't have to create an object for a class in order to initiate static method.
Rules and Regulation For Method-
#Rule-1 it is possible to provide Objects as a parameters(in real time project).
class Emp{ }
class
Student{ }
class Dog{ }
class
Animal{ }
class Test
{
void m1(Emp e,Student s)
{
System.out.println("m1
method");
System.out.println(e+"
"+s);
}
static void
m2(int a,Animal a1,Dog d)
{
System.out.println("m2
method");
System.out.println(a+"
"+a1+" "+d);
}
public
static void main(String[] args)
{ Test t =
new Test();
Emp e = new
Emp();
Student s =
new Student();
t.m1(e,s);
Animal x =
new Animal();
Dog d = new
Dog();
Test.m2(10,x,d);
}
}
In above example when we print reference
variables hash code is printed
The extra
classes (Dog,Animal…) these classes it may belongs to same module classes or
different module
classes.
#Rule-2 Java methods return type is mandatory, otherwise the compilation will generate error
message
“invalid method declaration; return type required “.
class Test
{
m1()
{
//Logic Here
}
}
error:
invalid method declaration; return type required
public
static void main(String[] args)
#Rule-3 Inside the class it is not possible to declare more than one method with same
signature(duplicate methods) , if we are trying to
declare with same signature compiler
generates error : “m1() is already defined in Test”
class Test
{
void m1()
{
System.out.println("m1 method");
}
void m1()
{
System.out.println("m1 method");
}
}
error: m1() is already defined in Test
#Rule-4 Declaring the class inside another class is called inner classes, java supports inner classes.
Declaring the methods inside other methods is
called inner methods but java not supporting inner
methods concept if we are trying to declare inner
methods compiler generate error message.
class Test
{
void m1()
{
void m2() //inner method : error: illegal start
of expression
{
}
}
}
error: illegal start of expression
#Rule-5 If the application continas both instnace & local variables with same name, in this case to represent instance variables we have two approaches.
#Rule-6 It is possible to print return value of the method
in two ways,#Rule-5 If the application continas both instnace & local variables with same name, in this case to represent instance variables we have two approaches.
1. Access by uisng this keyword
2. Access by using object.
‘This’ keyword is used to represent current class
object.
class Test
{
int a=100,b=200;
void add(int a,int b)
{
System.out.println(a+b);
System.out.println(this.a+this.b); //approach-1
Test t = new Test();
System.out.println(t.a+t.b); //approach-2
}
public static void main(String[] args)
{ Test t = new Test();
t.add(10,20);
}
}
Case 1: Invalid : inside the static area this
keyword not allowed
Int a=100,b=200;
static void add(int a,int b)
{
System.out.println(this.a+this.b);
}
Compilation error:-non-static variable this cannot
be referenced from a static context.
Case 2: In almost all cases we are using this
keyword to represent instacne variables but inside the
static area this keyword is not allowed hence use
object creation approach.
Int a=100,b=200;
static void add(int a,int b)
{
Test t = new Test();
System.out.println(t.a+t.b);
}
1. Hold the return value & print that value.
2. Directly print the value by calling method using
System.out.println()
class Test
{
int m1()
{
System.out.println("m1 method");
return 10;
}
public static void main(String[] args)
{
Test t =new Test();
int x = t.m1();
System.out.println("return value="+x);
//1-way printing return value
System.out.println("return
value="+t.m1()); //2-way printing return value
}
}
Observation : If the method is having return type
is void but if we are trying to call method by using
System.out.println() then compiler will generate
error message.
Static void m2()
{
System.out.println("m2 method");
}
System.out.println(Test.m2());
Compilation error:'void' type not allowed here
#Rule-7 coming Soon..
Team
QA acharya
Tags: Methods in java , Types of method in java , syntax of method , method calling in java , Declaration of method in java , How to call method , rules for declaring method in java .
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