Generics

Generics, introduced in Java 5, are a powerful feature that brings type-safety to the Java Collections Framework and beyond. Before generics, collections like `ArrayList` stored objects of type `Object`. This meant you could add any type of object to a collection, for example, adding an `Integer` to an `ArrayList` that was intended to hold only `String`s. The compiler wouldn't complain, but you would get a `ClassCastException` at runtime when you tried to retrieve the element and cast it back to a `String`. This lack of compile-time checking was a common source of bugs. Generics solve this problem by allowing you to specify the type of objects that a collection can hold. This is done using angle brackets (`<>`). For instance, `ArrayList<String>` declares an `ArrayList` that is guaranteed by the compiler to contain only `String` objects. If you try to add an `Integer` to this list, you will get a compilation error. This is a huge benefit because it shifts type errors from runtime to compile-time, making them much easier to find and fix. When you retrieve an element from a generic collection, you also don't need to cast it, as the compiler already knows its type. For example, `String name = names.get(0);` works without a cast. While generics are most visibly used with collections, you can also create your own generic classes, interfaces, and methods, enabling you to write flexible and reusable code that is also type-safe.