无法在ActionBar Android上添加徽标

Question

您好，我是Android的新手，我正在尝试在每个活动的动作栏中添加徽标和一个搜索视图。我试图在我的一个活动中实现徽标，但我会发现此错误，并且应用程序崩溃了。有人可以告诉我如何摆脱这一点吗？还有其他方法可以做我想做的事吗？

我直接从此网站 https://romannurik.github.io/androidassetstudio/index.html

错误

02-27 00:58:28.859 13851-13851/com.golstars.www.glostars E/AndroidRuntime: FATAL EXCEPTION: main
                                                                           Process: com.golstars.www.glostars, PID: 13851
                                                                           java.lang.RuntimeException: Unable to start activity ComponentInfo{com.golstars.www.glostars/com.golstars.www.glostars.MainFeed}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.app.ActionBar.setDisplayShowHomeEnabled(boolean)' on a null object reference
                                                                               at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
                                                                               at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
                                                                               at android.app.ActivityThread.-wrap12(ActivityThread.java)
                                                                               at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
                                                                               at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                               at android.os.Looper.loop(Looper.java:154)
                                                                               at android.app.ActivityThread.main(ActivityThread.java:6077)
                                                                               at java.lang.reflect.Method.invoke(Native Method)
                                                                               at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
                                                                               at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
                                                                            Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.app.ActionBar.setDisplayShowHomeEnabled(boolean)' on a null object reference
                                                                               at com.golstars.www.glostars.MainFeed$override.onCreate(MainFeed.java:96)
                                                                               at com.golstars.www.glostars.MainFeed$override.access$dispatch(MainFeed.java)
                                                                               at com.golstars.www.glostars.MainFeed.onCreate(MainFeed.java:0)
                                                                               at android.app.Activity.performCreate(Activity.java:6664)
                                                                               at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
                                                                               at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)
                                                                               at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707) 
                                                                               at android.app.ActivityThread.-wrap12(ActivityThread.java) 
                                                                               at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460) 
                                                                               at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                               at android.os.Looper.loop(Looper.java:154) 
                                                                               at android.app.ActivityThread.main(ActivityThread.java:6077) 
                                                                               at java.lang.reflect.Method.invoke(Native Method) 
                                                                               at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 
                                                                               at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)

我的主饲料方法

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main_feed);
        getSupportActionBar().setDisplayShowHomeEnabled(true);
        getSupportActionBar().setLogo(R.drawable.ic_action_logoandtext);
        getSupportActionBar().setDisplayUseLogoEnabled(true);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

activity_main_feed.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:fitsSystemWindows="true"
    tools:context="com.golstars.www.glostars.MainFeed">

    <include
        layout="@layout/activity_test"
        />
    <include
        layout="@layout/fabs"
        />

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

清单文件：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.golstars.www.glostars">
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:debuggable="true"
        android:supportsRtl="true"
        android:name="android.support.multidex.MultiDexApplication"
        android:theme="@style/AppTheme">
        <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>
        <activity
            android:name=".MainFeed"
            android:label="@string/title_activity_main_feed"
            android:theme="@style/AppTheme" />
        <activity
            android:name=".user_profile"
            android:label="@string/title_activity_user_profile"
            android:theme="@style/AppTheme.NoActionBar" />
        <activity
            android:name=".Fabs"
            android:theme="@style/AppTheme.NoActionBar" />
        <activity
            android:name=".testfeed"
            android:label="@string/title_activity_test"
            android:theme="@style/AppTheme.NoActionBar" />
        <activity
            android:name=".notification"
            android:label="@string/title_activity_notification"
            android:theme="@style/AppTheme.NoActionBar" />
        <activity
            android:name=".upload"
            android:label="@string/title_activity_upload"
            android:theme="@style/AppTheme.NoActionBar" />
        <activity
            android:name=".edit_profile"
            android:label="@string/title_activity_edit_profile"
            android:theme="@style/AppTheme.NoActionBar" />
        <activity
            android:name=".competitionUser"
            android:label="@string/title_activity_competition_user"
            android:theme="@style/AppTheme.NoActionBar" />
        <activity
            android:name=".competitionAll"
            android:label="@string/title_activity_competition_all"
            android:theme="@style/AppTheme.NoActionBar" />
        <activity
            android:name=".imagefullscreen"
            android:label="@string/title_activity_image_full_screen"
            android:theme="@style/AppTheme.NoActionBar" />
        <activity
            android:name=".commentModel"
            android:label="@string/title_activity_comment_model"
            android:theme="@style/AppTheme.NoActionBar"/>
    </application>
</manifest>

Answer 1

在 onCreate中，设置 toolbar first

Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayShowHomeEnabled(true);
getSupportActionBar().setLogo(R.drawable.ic_action_logoandtext);
getSupportActionBar().setDisplayUseLogoEnabled(true);