- 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 - Bound Types Erasure
Java Compiler replaces type parameters in generic type with their bound if bounded type parameters are used.
Example
package com.tutorialspoint; public class GenericsTester { public static void main(String[] args) { Box<Integer> integerBox = new Box<Integer>(); Box<Double> doubleBox = new Box<Double>(); integerBox.add(new Integer(10)); doubleBox.add(new Double(10.0)); System.out.printf("Integer Value :%d\n", integerBox.get()); System.out.printf("Double Value :%s\n", doubleBox.get()); } } class Box<T extends Number> { private T t; public void add(T t) { this.t = t; } public T get() { return t; } }
In this case, java compiler will replace T with Number class and after type erasure,compiler will generate bytecode for the following code.
package com.tutorialspoint; public class GenericsTester { public static void main(String[] args) { Box integerBox = new Box(); Box doubleBox = new Box(); integerBox.add(new Integer(10)); doubleBox.add(new Double(10.0)); System.out.printf("Integer Value :%d\n", integerBox.get()); System.out.printf("Double Value :%s\n", doubleBox.get()); } } class Box { private Number t; public void add(Number t) { this.t = t; } public Number get() { return t; } }
In both case, result is same −
Output
Integer Value :10 Double Value :10.0
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