# Erasure of Generic Methods

Java编译器也会擦除泛型函数传参中的类型参数，以下面的泛型函数为例：

```java
// Counts the number of occurrences of elem in anArray.
//
public static <T> int count(T[] anArray, T elem) {
    int cnt = 0;
    for (T e : anArray)
        if (e.equals(elem))
            ++cnt;
        return cnt;
}
```

`T`是无边界的，所以Java编译器将它替换为`Object`：

```java
public static int count(Object[] anArray, Object elem) {
    int cnt = 0;
    for (Object e : anArray)
        if (e.equals(elem))
            ++cnt;
        return cnt;
}
```

假设有如下几个类的定义：

```java
class Shape { /* ... */ }
class Circle extends Shape { /* ... */ }
class Rectangle extends Shape { /* ... */ }
```

我们可以编译一个通用的函数来画不同的形状：

```java
public static <T extends Shape> void draw(T shape) { /* ... */ }
```

Java编译器会将`T`替换为`Shape`：

```java
public static void draw(Shape shape) { /* ... */ }
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://eric3wade.gitbook.io/java/learning-the-java-language/generics/type-erasure/erasure-of-generic-methods.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.