Type erasure in java generics type erasure and java generics

okay, let's dive deep into type erasure in java generics. this is a crucial concept for understanding how generics work under the hood, and why they behave the way they do.

**what is type erasure?**

type erasure is a process by which the java compiler removes type parameters from the code during compilation. in essence, the generic type information you write in your java code (like `string`, `integer`, etc.) is only used during compile-time for type checking and isn't retained at runtime. at runtime, all generic types are represented by their "raw" type (usually `object` or the upper bound of the type parameter if one is specified).

**why type erasure? (backward compatibility)**

the primary reason for type erasure is to maintain backward compatibility with older versions of java that did not have generics. when generics were introduced in java 5, the designers didn't want to break existing code. type erasure allowed them to introduce generics without requiring a major overhaul of the java virtual machine (jvm).

**how type erasure works (simplified example)**

let's say you have the following generic class:

after type erasure, the `box` class effectively becomes:

key observations:

1. **type parameters disappear:** the `t` in `boxt` is gone.
2. **type parameters replaced by `object`:** `t` is replaced by `object` in the fields and method signatures. (unless there is an upper bound, which we'll see later).

**consequences of type erasure**

type erasure has several important consequences that you need to be aware of when working with generics:

1. **you cannot create instances of type parame ...

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