如何做一个'的.class“物业工作？ [英] How does a '.class' property work?

问题描述

第一次开发在Java中，和第一次开发的机器人，所以这是一个相当新手问题。

First time developing in Java, and first time developing for Android, so it's quite a newbie question.

目前，我有这个code：

I currently have this code:

public void onBtnClicked(View v){
    /** Handles button navigation */

    @SuppressWarnings("rawtypes")
    Class c;
    int viewId = v.getId();

    switch (viewId) {

    case R.id.btnNewTourny :
        c = NewTourny.class;
        break;
    case R.id.btnTeamEditor :
        c = EditTeam.class;
        break;
    case R.id.btnCatEditor :
        c = EditCat.class;
        break;
    case R.id.btnLoadTourny :
        c = EditCat.class;
        break;
    case R.id.btnNewCategory :
        c = NewCat.class;
        break;
    default :
        c = Main.class;
    }

    Intent myIntent = new Intent(v.getContext(), c);
    startActivityForResult(myIntent, 0);
}

短的问题：

什么的的的.class 的属性在做，f.ex.在 C = NewTourny 的的.class

What does the .class property do, f.ex. in 'c = NewTourny.class'?

为什么我不能投c以图尔尼（这是所有这些类的父类）？

Why can't I cast c as Tourny (which is the parent of all these classes)?

长的问题：

本目前处理所有的导航按钮在我的应用程序，并能正常工作。然而，正如你所看到的，我晚饭pressed一个'rawtype的警告，那来当我投C作为类。 现在，我真的想不警告，一个code，所以我想'哦，这些类是孩子的图尔尼'，所以我认为这是可行的，铸件C的图尔尼 - 但是，这并不正常工作。这时我才意识到，我真的不知道是什么codeNewTourny.class其实做了，这可能是线索，为什么我不能投c以图尔尼。那么，什么是的.class办？

This currently handles all button navigations throughout my app, and works fine. However, as you can see, I've suppressed a 'rawtype' warning, that comes when I cast c as a Class . Now, I really want a code without warnings, so I thought 'well, all these classes are a child of 'Tourny'', so I thought it would work, casting c as Tourny - but that does not work. Then I realised, that I didn't really know what the code "NewTourny.class" actually did, and that may be the clue to why I couldn't cast c as Tourny. So, what does .class do?

推荐答案

它并没有真正的执行的多。 NewTourney.class 更多的是一种特定语言的方式来写，这是类 NewTourney 的对象。这速记允许一个参考的类的的一个 NewTourney ，系统相对于处理特定的现有的实例 NewTourney 。

It doesn't really do much. NewTourney.class is more of a language specific way to write "the object which is the Class of NewTourney". This shorthand allows one to refer to the class of a NewTourney, as opposed to dealing with specific already existing instances of NewTourney.

在特定的情况下，我大胆猜测，该活动最终产生的的类的处理动作，或者在一个实例至少要保持动作的上下文敏感的数据。

In your specific case, I would hazard to guess that the Activity eventually creates an instance of the class to handle the action, or at least to hold the action's context sensitive data.

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