java-Constructors and Methdods – Automation Fraternity Blog

What is Constructor?

When the object is created, Java calls the constructor first. Any code you have in your constructor will then get executed. You don’t need to make any special calls to aconstructor method – they happen automatically when you create a new object. Constructor methods take the same name as the class.

Rules for creating java constructor

There are basically two rules defined for the constructor.

Constructor name must be same as its class name
Constructor must have no explicit return type

Types of java constructors

There are two types of constructors:

Default constructor (no-arg constructor)
Parameterized constructor

java constructor

Difference between constructor and method in java

There are many differences between constructors and methods. They are given below.

Java Constructor	Java Method
Constructor is used to initialize the state of an object.	Method is used to expose behaviour of an object.
Constructor must not have return type.	Method must have return type.
Constructor is invoked implicitly.	Method is invoked explicitly.
The java compiler provides a default constructor if you don’t have any constructor.	Method is not provided by compiler in any case.
Constructor name must be same as the class name.	Method name may or may not be same as class name.

package Day2;

  class EmployeeTest {

	/**
	 * @param args
	 */
	String name;
	int age;
	String designation;
	double salary;
	public EmployeeTest(String name){
		this.name = name;
	}
	// Assign the age of the Employee to the variable age.
	public void empAge(int empAge){
	age = empAge;
	}
	/* Assign the designation to the variable designation.*/
	public void empDesignation(String empDesig){
	designation = empDesig;
	}
	/* Assign the salary to the variable salary.*/
	public void empSalary(double empSalary){
	salary = empSalary;
	}
	/* Print the Employee details */
	public void printEmployee(){
	System.out.println("Name:"+ name );
	System.out.println("Age:"+ age );
	System.out.println("Designation:"+ designation );
	System.out.println("Salary:"+ salary);
	}
	

	
	

}
 public class Employee
 {
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		/* Create two objects using constructor */
		EmployeeTest empOne =new EmployeeTest("Nitin ");
		EmployeeTest empTwo =new EmployeeTest("Nikita ");
		// Invoking methods for each object created
		empOne.empAge(26);
		empOne.empDesignation("Senior Software Engineer");
		empOne.empSalary(1000);
		empOne.printEmployee();
		empTwo.empAge(21);
		empTwo.empDesignation("Software Engineer");
		empTwo.empSalary(500);
		empTwo.printEmployee();
	
	}
 }

package Day2;

class EmployeeTest {

/**

* @param args

String name;

int age;

String designation;

double salary;

public EmployeeTest(String name){

this.name = name;

}

// Assign the age of the Employee to the variable age.

public void empAge(int empAge){

age = empAge;

}

/* Assign the designation to the variable designation.*/

public void empDesignation(String empDesig){

designation = empDesig;

}

/* Assign the salary to the variable salary.*/

public void empSalary(double empSalary){

salary = empSalary;

}

/* Print the Employee details */

public void printEmployee(){

System.out.println("Name:"+ name );

System.out.println("Age:"+ age );

System.out.println("Designation:"+ designation );

System.out.println("Salary:"+ salary);

}

public class Employee

{

public static void main(String[] args) {

// TODO Auto-generated method stub

/* Create two objects using constructor */

EmployeeTest empOne =new EmployeeTest("Nitin ");

EmployeeTest empTwo =new EmployeeTest("Nikita ");

// Invoking methods for each object created

empOne.empAge(26);

empOne.empDesignation("Senior Software Engineer");

empOne.empSalary(1000);

empOne.printEmployee();

empTwo.empAge(21);

empTwo.empDesignation("Software Engineer");

empTwo.empSalary(500);

empTwo.printEmployee();

}

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