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Demystifying Java Generics

Here’s my take on Generics where I talk about Generics, Type Safety, Type Erasure. Hope you learn something new —

Java Generics are an important feature of the Java programming language that were introduced in Java 5.0. They provide a way to write code that is type-safe, meaning that errors caused by type mismatches can be caught at compile-time rather than at runtime. Generics allow developers to write generic classes and methods that can be used with different types of objects, without the need to write separate code for each type.

What are Generics?

Generics in Java are a way to make classes and methods more flexible, allowing them to work with a variety of data types. Before Generics were introduced, developers used the Object class to represent any type of data. This led to type safety issues as developers had to cast the Object back to the original type, which could result in runtime errors.

With Generics, developers can define classes and methods that work with a specific type of data, without having to specify the exact data type. For example, instead of creating a List object that can hold any type of object, we can create a List object that holds only a specific type of object, such as String, Integer, or Float.

Syntax of Generics

Generics are implemented using the following syntax:

class AGenericClass<T> {
 T someVariable;
 T someMethod(T someParam) {
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The “T” in this example represents the type parameter, which can be replaced with any other type, such as “E” for elements or “K” for keys. The type parameter can be used throughout the class to specify the type of data that will be used.

Advantages of Generics

Generics provide a number of advantages to Java developers:

Type Safety:

Generics provide type safety by catching type mismatches at compile-time rather than runtime. This results in fewer bugs and more reliable code.


Generics allow developers to write code that can be reused with different types of data. This reduces code duplication and makes the code more maintainable.


Generics can improve the performance of Java programs by reducing the amount of casting that needs to be done.


Generics make code easier to read and understand by providing more information about the types of data being used.

Some more examples

Here is an example of a generic class that can hold a list of objects of any type:

class MyClass<T> {
 private T[] elements;
 public void setElements(T[] elements) {
 this.elements = elements;
 public T[] getElements() {
 return elements;
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Here is an example of using the above class:

MyClass<Integer> intList = new MyClass<>();
Integer[] intArray = {1, 2, 3, 4, 5};
Integer[] elements = intList.getElements();
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In this example, an object of the “MyClass” class is created with a type parameter of “Integer”. An array of integers is then created and set to the “elements” field using the “setElements” method. The “getElements” method is called to retrieve the array of integers.

Happy learning!

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