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How can we Create Objects for a Class?

#1
#2

class Sphere {

  double radius; // Radius of a sphere

 

  Sphere() {

  }

  // Class constructor

  Sphere(double theRadius) {

    radius = theRadius; // Set the radius

  }

}

 

public class MainClass {

  public static void main(String[] arg){

    Sphere sp = new Sphere();    

  }

}
#3

Using the new keyword.
new is always followed by the constructor of the class.
For example, to create an Employee object, you write:

Employee employee = new Employee();
Here, ‘employee’ is an object reference of type Employee.

Once you have an object, you can call its methods and access its fields, by using the object reference.
You use a period (.) to call a method or a field.
For example:

objectReference.methodName
objectReference.fieldName
The following code, for instance, creates an Employee object and assigns values to its age and salary fields:

public class MainClass {

public static void main(String[] args) {
Employee employee = new Employee();
employee.age = 24;
employee.salary = 50000;
}

}
class Employee {
public int age;
public double salary;
public Employee() {
}
public Employee(int ageValue, double salaryValue) {
age = ageValue;
salary = salaryValue;
}
}