Creating Objects in java
In Java object-oriented programming, objects are instances of a class, or elements of a class structure or variable created from an object. When Java users create a new class object in a class program, they are creating a new instance of a real class object. This class object contains user-defined custom data types, data fields, and class Behavior methods.
Steps to create a new object in Java programming.
- Define a class – This serves as a foundational structural concept for creating new class objects in Java programs.
- Use the new keyword – The new keyword is used in Java class programs to create a new class object instance.
- Call a constructor – When Java users create a class object in an existing class, it is used to call the class constructor created in the class to initialize the created class object.
Syntax for creating a new object in a Java class.
ClassName objectName = new ClassName();
Example of creating a new class object in Java programming.
Here we create a new class program named Employee, which represents an employee data set with Employee class attributes such as emp_name, age, and salary. Next, we will create a new object for the Employee class.
public class Employee {
// Here we set the employee class fields with its data type
String emp_name;
String age;
int salary;
String address;
// Employee class Constructor, initialize the class object
public Employee(String emp_name, String age, String address, int salary) {
this.emp_name = emp_name; // Here we assign the emp_name of the employee class
this.age = age; // here we Assign the age of the employee class
this.address = address; // here we Assign the address of the employee class
this.salary = salary; // here we Assign the salary of the employee class
}
// Method to display employee class element
public void empInfo() {
System.out.println(“\n Employee emp_name is – ” + emp_name);
System.out.println(“\n Employee age is – ” + age);
System.out.println(“\n Employee address is – ” + address);
System.out.println(“\n Employee join Year is – ” + salary);
}
// here we create a Main method to create employee class objects
public static void main(String[] args) {
// Creating an object of the Employee class
Employee myEmployee = new Employee(“Bhavishi Deora”, “21”, “New Delhi”, 2022);
// Creating another object of the Employee class
Employee newEmployee = new Employee(“Siddhi Deora”, “19”, “Mumbai”, 2024);
// Calling the method to display details of each employee
myEmployee.empInfo();
newEmployee.empInfo();
}
}
Explanation of creating a new class object.
Class definition (employee).
- Employee class has four fields – Here in Employee class, emp_name, age, salary, and address are class fields. Which represent the attributes of the Employee class.
- When a new Employee object is created in the Employee class, the Employee constructor initializes the Employee(String emp_name, String age, String address, int salary) fields.
- Here, the method empInfo() prints the details information of the Employee class.
Creating new objects in the Employee class.
Employee myEmployee = new Employee(“Bhavishi Deora”, “21”, “New Delhi”, 2022) creates a new object of type Employee, myEmployee, and initializes it with the class object values ”Bhavishi Deora”, “21”, “New Delhi”, 2022 for emp_name, age, address, and salary, respectively.
Employee newEmployee = new Employee(“Siddhi Deora”, “19”, “Mumbai”, 2024); creates another object, the newEmployee class object, with different values.
Calling methods on the Employee class object.
myEmployee.empInfo(); calls the empInfo method on the myEmployee object and prints its details to the console screen.
newEmployee.empInfo(); performs the same process for the newEmployee object.
Things to remember when creating a new object in a Java class.
Creating a Java Class Object.
- To create an object of a user-defined class in a Java class, use the class constructor method followed by the new keyword.
- The new constructor in a Java program is responsible for initializing the object’s attributes.
Accessing new fields and methods in a class object.
- In a Java program, users can access and manage the fields and methods of a class object by using the . operator. For example, myEmployee.empInfo() or newEmployee.empInfo() can access class fields.
Creating Multiple Objects in a Java Class.
Java programmers can create as many new class objects as they want from a single class. Each created class object has a copy of its class fields and calling methods.
Java Class Constructor Overloading Method.
Java programmers can create or define multiple user-defined constructors in a class with multiple variable parameters. This process is known as constructor overloading.
Example of Java class constructor overloading.
public class Employee {
// Here we set the employee class fields with its data type
String emp_name;
String age;
int salary;
// Create a constructor with variable parameters
public Employee(String emp_name, String age, int salary) {
this.emp_name = emp_name;
this.age = age;
this.salary = salary;
}
// create Constructor with default user define values
public Employee() {
this.emp_name = “Unknown”;
this.age = “not defined”;
this.salary = 000;
}
// Method to display employee class element
public void empInfo() {
System.out.println(“Employee Name is – ” + emp_name);
System.out.println(“Employee Age is – ” + age);
System.out.println(“Employee Salary is – ” + salary);
}
public static void main(String[] args) {
// Creating an object of the Employee class
Employee myEmployee = new Employee(“Bhavishi Deora”, “21”, 2022);
// here we’re creating an object using the default constructor
Employee defaultemployee = new Employee();
myEmployee.empInfo(); // here it displays myEmployee details
defaultemployee.empInfo(); // here it displays defaultemployee details
}
}
Java class constructor overloading explanation.
- In this example, you have two class constructors defined: one that initializes the class fields with a specific Employee class value, and another that assigns and displays a default class element value.
