无法推断ArrayAdapter<>的类型参数 [英] Cannot infer type arguments for ArrayAdapter<>

问题描述

我仍然在处理日历，我几乎已经设法集成了 https://github.com/SundeepK/CompactCalendarView 放入我的片段之一.仅剩一个错误，我做了一些研究，其他人也遇到了问题，例如ArrayList<>.

I am still playing around with my calendar, I already nearly managed to integrate the https://github.com/SundeepK/CompactCalendarView into one of my fragments. There is just one error left, i did some research, others got the problem too for example with ArrayList<>.

示例代码:

final ArrayAdapter adapter = new ArrayAdapter<>
            (this,android.R.layout.simple_list_item_1, mutableBookings);

IDE会说:

Error:(87, 38) error: cannot infer type arguments for ArrayAdapter<>

注意:C:... \ Uebersicht.java使用或覆盖不推荐使用的API. 注意:有关详细信息，请使用-Xlint:deprecation重新编译.

Note: C:...\Uebersicht.java uses or overrides a deprecated API. Note: Recompile with -Xlint:deprecation for details.

我已经尝试过重新编译，但是结果似乎不起作用

Uebersicht.java:87: error: cannot find symbol
    final ArrayAdapter adapter = 
          new ArrayAdapter<>(this,android.R.layout.simple_list_item_1, mutableBookings);


Uebersicht.java:87: error: cannot find symbol 
final ArrayAdapter adapter = 
          new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, mutableBookings);    


Uebersicht.java:87: error: package android.R does not exist
    final ArrayAdapter adapter = 
          new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, mutableBookings);    

如果有必要，我也可以发布完整的Fragment类，它必须与我的API以及ArrayAdapter正在使用的API有关吗?别忘了我只是一个初学者，我只是想自己做一些事情.

I can post my full Fragment class too if it's necessary, it must be something with my API and the API the ArrayAdapter is using? Don't forget I am just a beginner, I am trying to do just some stuff all by myself.

推荐答案

您需要将Context传递给ArrayAdapter的构造方法.您实际上是在Fragment类中对其进行初始化，因此this作为上下文无效.尝试致电

You need to pass a Context to the Constructor of ArrayAdapter. You're actually in initializing it in a Fragment class, so this is not valid as a Context. Try calling

final ArrayAdapter adapter = new ArrayAdapter<String>(getActivity(), 
                                android.R.layout.simple_list_item_1,
                                mutableBookings);

这篇关于无法推断ArrayAdapter&lt;&gt;的类型参数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！