无法加载AppCompat ActionBar

Question

I'm having problems rendering some code in android studio, I'm able to run the app but in the preview i got these errors:

Failed to load AppCompat ActionBar with unknown error.

The following classes could not be instantiated:
- android.support.v7.widget.AppCompatImageView (Open Class, Show Exception, Clear Cache)
- android.support.v7.widget.ActionBarContainer (Open Class, Show Exception, Clear Cache)
- android.support.v7.widget.Toolbar (Open Class, Show Exception, Clear Cache)
- android.support.v7.widget.AppCompatTextView (Open Class, Show Exception, Clear Cache)
- android.support.v7.widget.ActionBarContextView (Open Class, Show Exception, Clear Cache)
- android.support.v7.app.WindowDecorActionBar (Open Class, Show Exception, Clear Cache)
- android.support.v7.widget.ActionBarOverlayLayout (Open Class, Show Exception, Clear Cache)

Here's my layout:

 <RelativeLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:paddingLeft="@dimen/activity_horizontal_margin"
     android:paddingRight="@dimen/activity_horizontal_margin"
     android:paddingTop="@dimen/activity_vertical_margin"
     android:paddingBottom="@dimen/activity_vertical_margin"
     tools:context=".MainActivity">

     <TextView android:text="@string/hello_world" android:layout_width="wrap_content"
         android:layout_height="wrap_content" />

 </RelativeLayout>

And here's my graddle:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 25
    buildToolsVersion '26.0.2'

    defaultConfig {
        applicationId "com.sourcey.materialloginexample"
        minSdkVersion 15
        targetSdkVersion 25
        versionCode 1
        versionName "1.0"
        android.defaultConfig.javaCompileOptions.annotationProcessorOptions.includeCompileClasspath = true
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:25.0.1'
    compile 'com.android.support:design:25.0.1'
    compile 'com.jakewharton:butterknife:7.0.1'
}

Any idea what compatibility problem do i have?

Answer 1

This one here solved my problem without changing library versions.

Go to @styles xml file and change this line

<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar"> </style>

to:

<style name="AppTheme" parent="Base.Theme.AppCompat.Light.DarkActionBar"> </style>

Answer 2

You should change compileSdkVersion and targetSdkVersion . Your problem has already answer, for more details you can check here https://stackoverflow.com/a/47067754/3797722

Answer 3

There are many ways to solve this problem. The best and the easiest one is to open build.gradle (Module: app) file in Gradle Scripts folder. In dependencies you have to make only one change. In second line of the dependencies curly bracket, change "alpha3" to "alpha1".

It should work perfectly fine.