以下类不能被实例化

问题描述

在我的homeactivity.xml它说：
以下类不能被实例化：
- android.support.design.widget.CoordinatorLayout（公开课，显示异常，清除缓存）
- android.support.design.widget.AppBarLayout（公开课，显示异常，清除缓存）
- android.support.design.widget.FloatingActionButton（公开课，显示异常，清除缓存）

On my homeactivity.xml it says:The following classes could not be instantiated:- android.support.design.widget.CoordinatorLayout (Open Class, Show Exception, Clear Cache)- android.support.design.widget.AppBarLayout (Open Class, Show Exception, Clear Cache)- android.support.design.widget.FloatingActionButton (Open Class, Show Exception, Clear Cache)

下面是我的code
    

Here is my code

<android.support.design.widget.AppBarLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:theme="@style/AppBarOverlay">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="#ff4747"
        app:popupTheme="@style/PopupOverlay" />


<include layout="@layout/content_home" />

<android.support.design.widget.FloatingActionButton
    android:id="@+id/fab"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="bottom|end"
    android:layout_margin="@dimen/fab_margin"
    android:src="@android:drawable/ic_dialog_email"
    android:background="#001f9c" />

</android.support.design.widget.AppBarLayout>

我不知道为什么会这样。是否有人可以帮助？

I don't know why this happened. Can someone please help?

推荐答案

作为注释，你必须包括依赖的设计是这样，这将是下添加在依赖的的build.gradle 应用模块块>

as commented you have to include the dependencies for design which is like this, this will be added under the dependencies block of the app module of the build.gradle

compile 'com.android.support:design:23.1.1'

应该是这样..

it should be something like this ..

如果在设计 依赖不包含在的build.gradle 并尝试在你的问题使用提到类您将无法呈现的类和您在布局得到错误会是这样的。

if the design dependencies is not included in the build.gradle and you try to use mentioned classes in your question you will not be able to render those classes and the error you get in layout would be something like this

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