14. Dynamic method dispatch in java


✔ JAVA CHAPTERS:-

1. Introduction to Java
2. Features of Java
3. Java Virtual Machine
4. D/F B/W JVM, JRE, JDK
5. Java Data Types
6. Java Programs
7. Setting Java Path
8. OOPs Concepts
9. Object & Class In Java
10. OOPs Continued
11. Encapsulation & Polymorphism
12. Method Overloading
13. Method Overriding
14. Dynamic Method Dispatch
15. Association In Java
16. Inheritance in Java
17. Aggregation in java
18. Command Line Argument
19. Execute Command Line
20. Read Input From Command Line
21. Abstract Class In Java
22. Interface in Java
23. Cutom Marker Interface
24. Constructor In Java
25. Package in Java
26. Acess Modifier In Java
27. Static Import In Java
28. Package Class In Java
29. This Keyword
30. Instance Intializer Block
31. Super Keyword
32. Static Keyword
33. Final Keyword


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Dynamic method dispatch in java


dynamic method dispatch
Dynamic method dispatch in Java

Dynamic method dispatch is a mechanism to resolve overridden method call at run time instead of compile time. It is based on the concept of up-casting (A super class reference variable can refer subclass object.).

Example 1:

/**
 * This program is used for simple method overriding example.
 * with dynamic method dispatch.
 * @author java tutorial point
 */
class Student {
      /**
       * This method is used to show details of a student.
       * @author java tutorialpoint
       */
      public void show(){
            System.out.println("Student details.");
      }
}
 
public class CollegeStudent extends Student {
      /**
       * This method is used to show details of a college student.
       * @author java tutorial point
       */
      public void show(){
            System.out.println("College Student details.");
      }
 
      //main method
      public static void main(String args[]){
       //Super class can contain subclass object.   
       Student obj = new CollegeStudent();
 
       //method call resolved at runtime
       obj.show();
      }
}

Output:

College Student details.
School Student details.

Example 2:

/**
 * This program is used for simple method overriding example.
 * @author javatutorialpoint
 */
class Student {
      /**
       * This method is used to show details of a student.
       * @author javatutorialpoint
       */
       public void show(){
              System.out.println("Student details.");
       }
}
 
public class CollegeStudent extends Student {
       /**
         * This method is used to show details of a college student.
         * @author java tutorial point
         */
       public void show(){
             System.out.println("College Student details.");
       }
 
       //main method
       public static void main(String args[]){
           //Super class can contain subclass object.   
           Student obj = new CollegeStudent();
           //method call resolved at runtime
           obj.show();
      }
 
}

Output:

College Student details.



Note: Only super class methods can be overridden in subclass, data members of super class cannot be overridden.

/**
 * This program is used for simple method overriding example.
 * with dynamic method dispatch.
 * @author java tutorial point
 */
class Student {
      int maxRollNo = 200;
}
 
class SchoolStudent extends Student{
      int maxRollNo = 120;
}
 
class CollegeStudent extends SchoolStudent{
      int maxRollNo = 100;
}
 
public class StudentTest {
      public static void main(String args[]){
       //Super class can contain subclass object.   
       Student obj1 = new CollegeStudent();
       Student obj2 = new SchoolStudent();
 
       //In both calls maxRollNo of super class will be printed.
       System.out.println(obj1.maxRollNo);
       System.out.println(obj2.maxRollNo);
      }
}

Output:

200
200

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