Can we throw an object of generic class in java?


Generics is a concept in Java where you can enable a class, interface and, method, accept all (reference) types as parameters. In other words it is the concept which enables the users to choose the reference type that a method, constructor of a class accepts, dynamically. By defining a class as generic you are making it type-safe i.e. it can act up on any data type.

Example

 Live Demo

class Student<T>{
   T age;
   Student(T age){
      this.age = age;
   }
   public void display() {
      System.out.println("Value of age: "+this.age);
   }
}
public class GenericsExample {
   public static void main(String args[]) {
      Student<Float> std1 = new Student<Float>(25.5f);
      std1.display();
      Student<String> std2 = new Student<String>("25");
      std2.display();
      Student<Integer> std3 = new Student<Integer>(25);
      std3.display();
   }
}

Output

Value of age: 25.5
Value of age: 25
Value of age: 25

Throwing a generic class object

To create a custom class that is throwable using the throws clause you need to extend the throwable class.

class MyException extends Throwable{
   MyException(String msg){
      super(msg);
   }
}

Therefore if you need to throw an object of generic type, you should be able to extend the Throwable class from it. But, if you try to do so a compile time error will be generated. Therefore, you cannot throw an object of the Generic class using the throws clause.

Example

 Live Demo

class Student<T>extends Throwable{
   T age;
   Student(T age){
      this.age = age;
   }
   public void display() {
      System.out.println("Value of age: "+this.age);
   }
}
public class GenericsExample {
   public static void main(String args[]) {
   }
}

Compile time error

GenericsExample.java:1: error: a generic class may not extend java.lang.Throwable
class Student<T>extends Throwable{
                        ^
1 error
raja
Published on 09-Sep-2019 11:18:27
Advertisements