Blog

Java Generics – No Static field

This topic is about Java Generics – No Static field.

Using generics, type parameters are not allowed to be static. As static variable is shared among object so compiler can not determine which type to used. Consider the following example if static type parameters were allowed.

Example

package com.Adglob;

public class GenericsTester {
   public static void main(String[] args) {
      Box<Integer> integerBox = new Box<Integer>();
	  Box<String> stringBox = new Box<String>();
	  
      integerBox.add(new Integer(10));
      printBox(integerBox);
   }

   private static void printBox(Box box) {
      System.out.println("Value: " + box.get());
   }  
}

class Box<T> {
   //compiler error
   private static T t;

   public void add(T t) {
      this.t = t;
   }

   public T get() {
      return t;
   }   
}

As stringBox and integerBox both have a stared static type variable, its type can not be determined. Hence static type parameters are not allowed.

In this topic we learned about Java Generics – No Static field. To know more, Click Here.

Leave a Reply