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Java Program to demonstrate multiple inheritance using interfaces.

Java Code Example — Abstract and Interface Programs

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Java Program to demonstrate multiple inheritance using interfaces.

Objective

Write a Java program to demonstrate Multiple Inheritance using interfaces.

Algorithm / Approach

  1. Create a first interface SubMarks with a method getMarks().
  2. Create a second interface Sports with a method sportMarks().
  3. Create a Result class that implements BOTH interfaces separated by a comma (implements SubMarks, Sports).
  4. Provide concrete implementations for both methods inside the Result class.
  5. Call both methods from the main class.
Result.java 
import java.util.Scanner;
interface SubMarks {
 public void getMarks();
}
interface Sports {
 public void sportMarks();
}
class Result implements SubMarks,Sports {
 int marks,sport,total;
 Scanner s = new Scanner(System.in);
 public void getMarks() {
  System.out.print("Subject Marks: ");
  marks = s.nextInt();
 }
 public void sportMarks() {
  System.out.print("Sport Marks: ");
  sport = s.nextInt();
 }
 public void display() {
  total = marks+sport;
  System.out.println("Total - "+total);
 }
}
class Main {
 public static void main(String[] a)
 {
  Result r =new Result();
  r.getMarks();
  r.sportMarks();
  r.display();
 }
}

Expected Output

Subject Marks: 90
Sport Marks: 80
Total - 170

Explanation of the Program

  • Java strictly prohibits a class from extending more than one parent class (Multiple Inheritance of State) because it leads to the "Diamond Problem" (ambiguity if both parents have a method with the same name).
  • However, Java ALLOWS multiple inheritance of interfaces. Why? Because interfaces only contain empty method signatures.
  • If both interfaces require a method called getMarks(), there is no ambiguity. The child class just provides one implementation that satisfies both contracts.

Complexity

Time Complexity O(1)
Space Complexity O(1)
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