在 Android Studio 中创建新项目！不运行

Question

我已经在使用 Eclipse，我想迁移到 Android Studio。 我安装了 Android Studio，我刚刚创建了新项目，但它没有运行..

原木猫：

08-15 04:49:48.210 1357-1357/? E/AndroidRuntime: FATAL EXCEPTION: main
    java.lang.RuntimeException: Unable to start activity ComponentInfo{vakili.ramin.apps.myapplication/vakili.ramin.apps.myapplication.FullscreenActivity}: android.view.InflateException: Binary XML file line #36: Error inflating class android.support.v7.widget.Toolbar
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
        at android.app.ActivityThread.access$600(ActivityThread.java:141)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:5041)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
        at dalvik.system.NativeStart.main(Native Method)
    Caused by: android.view.InflateException: Binary XML file line #36: Error inflating class android.support.v7.widget.Toolbar
        at android.view.LayoutInflater.createView(LayoutInflater.java:613)
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:687)
        at android.view.LayoutInflater.rInflate(LayoutInflater.java:746)
        at android.view.LayoutInflater.rInflate(LayoutInflater.java:749)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:352)
        at android.support.v7.app.AppCompatDelegateImplV7.ensureSubDecor(AppCompatDelegateImplV7.java:299)
        at android.support.v7.app.AppCompatDelegateImplV7.setContentView(AppCompatDelegateImplV7.java:246)
        at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:106)
        at vakili.ramin.apps.myapplication.FullscreenActivity.onCreate(FullscreenActivity.java:90)
        at android.app.Activity.performCreate(Activity.java:5104)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230) 
        at android.app.ActivityThread.access$600(ActivityThread.java:141) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234) 
        at android.os.Handler.dispatchMessage(Handler.java:99) 
        at android.os.Looper.loop(Looper.java:137) 
        at android.app.ActivityThread.main(ActivityThread.java:5041) 
        at java.lang.reflect.Method.invokeNative(Native Method) 
        at java.lang.reflect.Method.invoke(Method.java:511) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
        at dalvik.system.NativeStart.main(Native Method)

这是我的 SDK：

我还尝试重新同步项目 - 清理和重建 - 使缓存无效/重新启动 -

Build.Gradle 文件：

apply plugin: 'com.android.application'

android {
compileSdkVersion 22
buildToolsVersion "19.1.0"

defaultConfig {
    applicationId "vakili.ramin.apps.test3"
    minSdkVersion 15
    targetSdkVersion 22
    versionCode 1
    versionName "1.0"
}
buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-   rules.pro'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])

    compile 'com.android.support:appcompat-v7:22.2.1'
}

似乎一切都很好。但是.... 安卓工作室好诡异！

编辑：main.xml

    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    android:background="@drawable/background_03" >


    <ImageView
        android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:id="@+id/imageView"
       android:layout_gravity="center_horizontal"
       android:background="@drawable/abc_btn_check_to_on_mtrl_015" />
</LinearLayout>

我刚刚添加了一个 imageView。和一个可绘制的背景！

编辑 2：用于全屏活动的 xml

<FrameLayout 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:background="#0099cc"
tools:context="vakili.ramin.apps.myapplication.FullscreenActivity">

<!-- The primary full-screen view. This can be replaced with whatever view
     is needed to present your content, e.g. VideoView, SurfaceView,
     TextureView, etc. -->
<TextView
    android:id="@+id/fullscreen_content"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:keepScreenOn="true"
    android:text="@string/dummy_content"
    android:textColor="#33b5e5"
    android:textSize="50sp"
    android:textStyle="bold" />

<!-- This FrameLayout insets its children based on system windows using
     android:fitsSystemWindows. -->
<FrameLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true">

    <LinearLayout
        android:id="@+id/fullscreen_content_controls"
        style="?metaButtonBarStyle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|center_horizontal"
        android:background="@color/black_overlay"
        android:orientation="horizontal"
        tools:ignore="UselessParent">

        <Button
            android:id="@+id/dummy_button"
            style="?metaButtonBarButtonStyle"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="@string/dummy_button" />

    </LinearLayout>
</FrameLayout>

</FrameLayout>

Answer 1

Caused by: java.lang.NullPointerException
    at android.app.Activity.findViewById(Activity.java:1884)
    at net.dominik.genpush.settings.<init>(settings.java:23)

在初始化活动设置对象（可能是成员变量）时调用 findViewById() 太早了。您发布的代码没有显示。

您实际上只能在 onCreate() 或更高版本中调用活动函数。

还将 findViewById() 放在 setContentView() 之后，这样它实际上可以返回 null 以外的内容。

你可能忘记了检查你的java代码

Answer 2

将您的父主题替换为 @style/Theme.AppCompat.NoActionBar

<style name="AppTheme" parent="@style/Theme.AppCompat.NoActionBar">
   <item name="windowActionBar">false</item>
   <item name="android:windowNoTitle">true</item>
</style>

或替换

android:Theme.Material.Light.NoActionBar

使用支持库主题

Theme.AppCompat.Light.NoActionBar

在 style.xml（无论版本如何）中解决了该问题。