- Java Generics Tutorial
- Java Generics - Home
- Java Generics - Overview
- Java Generics - Environment Setup
- Examples - Generic Classes
- Java Generics - Generic Classes
- Type Parameter Naming Conventions
- Java Generics - Type inference
- Java Generics - Generic Methods
- Java Generics - Multiple Type
- Java Generics - Parameterized Types
- Java Generics - Raw Types
- Examples - Bounded Type
- Bounded Type Parameters
- Java Generics - Multiple Bounds
- Examples - Collections
- Java Generics - Generic List
- Java Generics - Generic Set
- Java Generics - Generic Map
- Examples - Wild Cards
- Upper Bounded Wildcards
- Generics - Unbounded Wildcards
- Lower Bounded Wildcards
- Generics - Guidelines for Wildcards
- Type Erasure
- Java Generics - Types Erasure
- Java Generics - Bound Types Erasure
- Unbounded Types Erasure
- Java Generics - Methods Erasure
- Restrictions on Generics
- Java Generics - No Primitive Types
- Java Generics - No Instance
- Java Generics - No Static field
- Java Generics - No Cast
- Java Generics - No instanceOf
- Java Generics - No Array
- Java Generics - No Exception
- Java Generics - No Overload
- Java Generics Useful Resources
- Java Generics - Quick Guide
- Java Generics - Useful Resources
- Java Generics - Discussion
Java Generics - No Primitive Types
Using generics, primitive types can not be passed as type parameters. In the example given below, if we pass int primitive type to box class, then compiler will complain. To mitigate the same, we need to pass the Integer object instead of int primitive type.
Example
package com.tutorialspoint; public class GenericsTester { public static void main(String[] args) { Box<Integer> integerBox = new Box<Integer>(); //compiler errror //ReferenceType //- Syntax error, insert "Dimensions" to complete ReferenceType //Box<int> stringBox = new Box<int>(); integerBox.add(new Integer(10)); printBox(integerBox); } private static void printBox(Box box) { System.out.println("Value: " + box.get()); } } class Box<T> { private T t; public void add(T t) { this.t = t; } public T get() { return t; } }
This will produce the following result −
Output
Value: 10
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