什么是<？>意味着在Android方法签名？ [英] What does <?> mean in Android method signature?

问题描述

  public void onItemClick（AdapterView<？>父，View v，int position，long id）
  

<



谢谢。

解决方案

/ div>

AdapterView 是一个泛型类。它以另一种数据类型作为参数，然后以某种方式将其操作定制为该类型。通常，您将声明一个 AdapterView 类似于

  AdapterView< String> ; avs = new AdapterView< String>（...）; 
  

这指的是一个 AdapterView code> String s。

现在，给出所有这些：<？> code>表示这个方法将接受一个 AdapterView ，而不管它被定制的类。这是一个通配符类型说明符。

I 'm going through a code and found the following method declaration.

public void onItemClick(AdapterView<?> parent, View v, int position, long id)

What does <?> mean here?

Thank you.

解决方案

AdapterView is a generic class. It takes another data type as a parameter, and its operation is then customized towards that type, in a way. Normally, you'll declare an AdapterView something like

AdapterView<String> avs = new AdapterView<String>(...);

This refers to an AdapterView customized for Strings.

Now, given all that: the <?> means that this method will accept an AdapterView regardless of the class it's customized for. It's a wildcard type specifier.

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