Android Studio：启动屏幕后应用程序崩溃[重复]

Question

在我尝试实现启动画面后，我的应用程序崩溃了。 不知道问题出在哪里。

我尝试了 2 个小时来解决这个问题，甚至研究了网络，但不知何故我无法让它工作。 也许你们可以查看代码并给我一些提示？我会很感激的。

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools"
    package="com.example.noctis">

    <application tools:ignore="GoogleAppIndexingWarning"
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">

        <activity
            android:name=".impressum"
            android:label="@string/title_activity_impressum"
            android:theme="@style/AppTheme.NoActionBar" />
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name"
            android:theme="@style/AppTheme.Launcher">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

launch_screen.xml

<?xml version="1.0" encoding="utf-8"?>

<layer-list xmlns:android="http://schemas.android.com/apk/res/android" android:opacity="opaque">

    <item android:drawable="@color/colorContentBackground"/>

    <item>
        <bitmap
            android:src="@drawable/rsz_l52878klein"
            android:gravity="center"/>
    </item>

</layer-list>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/colorContentBackground"
    tools:context=".MainActivity">



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


        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="@color/colorPrimary"
            app:popupTheme="@style/AppTheme.PopupOverlay"
            android:layout_gravity="center_horizontal">

            <ImageView
                android:layout_width="110dp"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:src="@drawable/rsz_l52878"/>

        </android.support.v7.widget.Toolbar>

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

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

    <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="16dp"
        app:backgroundTint="@color/actionButton"
        app:fabSize="normal"
        android:src="@drawable/ic_add_black_32dp" />

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

styles.xml

<resources>

    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
    </style>

    <style name="AppTheme.Launcher" parent="AppTheme">
        <item name="android:windowBackground">@drawable/launch_screen</item>
    </style>


    <style name="AppTheme.NoActionBar">
        <item name="windowActionBar">false</item>
        <item name="windowNoTitle">true</item>
    </style>

    <style name="AppTheme.AppBarOverlay" parent="ThemeOverlay.AppCompat.Dark.ActionBar" />

    <style name="AppTheme.PopupOverlay" parent="ThemeOverlay.AppCompat.Light" />
</resources>

MainActivity.java

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = findViewById(R.id.toolbar);
        toolbar.setTitle("");
        setSupportActionBar(toolbar);


        FloatingActionButton fab = findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

所以..会显示实际的初始屏幕，但之后应用程序就会崩溃。我不明白为什么：/

编辑：（崩溃日志）

2019-03-25 21:06:18.588 14651-14651/com.example.noctis E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.noctis, PID: 14651
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.noctis/com.example.noctis.MainActivity}: java.lang.IllegalStateException: This Activity already has an action bar supplied by the window decor. Do not request Window.FEATURE_SUPPORT_ACTION_BAR and set windowActionBar to false in your theme to use a Toolbar instead.
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3107)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3250)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1947)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7032)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:964)
     Caused by: java.lang.IllegalStateException: This Activity already has an action bar supplied by the window decor. Do not request Window.FEATURE_SUPPORT_ACTION_BAR and set windowActionBar to false in your theme to use a Toolbar instead.
        at android.support.v7.app.AppCompatDelegateImpl.setSupportActionBar(AppCompatDelegateImpl.java:345)
        at android.support.v7.app.AppCompatActivity.setSupportActionBar(AppCompatActivity.java:130)
        at com.example.noctis.MainActivity.onCreate(MainActivity.java:21)
        at android.app.Activity.performCreate(Activity.java:7327)
        at android.app.Activity.performCreate(Activity.java:7318)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1271)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3087)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3250) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1947) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loop(Looper.java:214) 
        at android.app.ActivityThread.main(ActivityThread.java:7032) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:964) 
2019-03-25 21:06:18.599 14651-14651/com.example.noctis I/Process: Sending signal. PID: 14651 SIG: 9

Answer 1

是因为下面的错误：

 Caused by: java.lang.IllegalStateException: This Activity already has an action bar supplied by the window decor. Do not request Window.FEATURE_SUPPORT_ACTION_BAR and set windowActionBar to false in your theme to use a Toolbar instead.

这意味着您的活动中有一个工具栏，但您的活动样式中也使用了一个工具栏。您需要在 MainActivity 中使用 "AppTheme.NoActionBar"，如下所示：

    <activity
        android:name=".MainActivity"
        android:label="@string/app_name"
        android:theme="@style/AppTheme.NoActionBar">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

Answer 2

您可能需要更新 MainActivity.java 的主题

 <!-- Base application theme. -->
 <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
<!-- Customize your theme here. -->
<item name="colorPrimary">@color/colorPrimary</item>
<item name="colorPrimaryDark">@color/colorPrimaryDark</item>
<item name="colorAccent">@color/colorAccent</item>
<item name="windowActionBar">false</item>
<item name="windowNoTitle">true</item>
</style>

Answer 3

这个 Activity 已经有一个由窗口装饰提供的操作栏。不要在主题中请求 Window.FEATURE_SUPPORT_ACTION_BAR 并将 windowActionBar 设置为 false 以使用工具栏。

完全按照它的建议去做怎么样？

<style name="AppTheme.Launcher" parent="AppTheme">
    <item name="android:windowBackground">@drawable/launch_screen</item>
    <item name="windowActionBar">false</item>
    <item name="windowNoTitle">true</item>
</style>