What is Constructor?
1.Constructorin java is special method that is used to initailze objects.
2.It is automatically called when an object of a class is created.
3.It is used to set initial values for object attributes.
Rules of Constructor:
◆ Constructor name must be the same as the class name.
◆ Constructor has no return type (not even void).
◆ Constructor is called automatically when using the new keyword.
◆ Constructors can be overloaded.
Types of Constructors:
- Default Constructor
- No-Argument Constructor
- Parameterized Constructor
Important Keywords:
◆ new → Creates an object and calls the constructor.
◆ this() → Calls another constructor in the same class.
◆ super() → Calls the parent class constructor.
Create a constructor:
Explanation:
*Creates a class named Main.
public class Main {
*Declares an instance variable x.
int x;
*Declares an instance variable x.
public Main() {
x = 5;
}
◆ This is the constructor.
◆ It has the same name as the class (Main).
◆ It has no return type.
◆ It runs automatically when an object is created.
◆ It initializes x to 5.
Main myObj = new Main();
◆ Creates a new object.
◆ Automatically calls the constructor.
◆ The constructor sets x = 5.
System.out.println(myObj.x);
◆ Prints the value of x.
output: 5
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