Why We Need Generics In Java?

Generics are introduced in Java 5 for enable types (classes and interfaces) to be parameters when defining classes, interfaces and methods. They are implemented by Java compiler as a front-end conversion called erasure . The benefits of generic as follows:

Elimination of Type Casting
Stronger type checking at compile time
Enabling programmers to implement generic algorithms

Elimination of Type Casting

Generics provide the type checking at compile time . Finding bugs in compile-time can save time for debugging java program, because compile-time bugs are much easier to find and fix. If you use generics , you need not to perform the type casting explicitly. Java compiler applies strong type checking if you use generics in your code and shows errors if the code violates the type safety. Thus removing the risk of ClassCastException . Before Generics

List list = new ArrayList(); list.add("Before Generic"); String s = (String) list.get(0);

In the above case we can see typecasting in last line.

After Generics

List < String> list = new ArrayList < String>(); list.add("After Generic"); String s = list.get(0);

Stronger type checking at compile time

Finding bugs in compile-time can save time for debugging java program, because compile-time bugs are much easier to find and fix. Java compiler applies strong type checking to generic code and issues errors if the code violates type safety. Example

List < String> list = new ArrayList < String>(); list.add("After Generic"); String s = list.get(0);

The compiler is responsible for understanding Generics at compile time. Above code is checked at compile time, so it is guaranteed that no problem will occur at runtime.

Enabling developers to implement generic algorithms

By using generics , developers can implement generic algorithms that work on collections of different types, can be customized, and are type safe and easier to read.

Next : What does it mean to be static in Java?

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