Java android中actionbar的NullpointerException

我是android新手，正在制作一个滑动标签演示和引用链接的演示，一步一步，但我遇到了一个问题，当我运行应用程序时，它抛出了nullpointerexception，请查看下面的代码并帮助我弄清楚

main_listing.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.view.ViewPager
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/pager"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

<resources>


    <style name="MyRadioButtonStyle" parent="@android:style/Widget.CompoundButton.RadioButton">
        <item name="android:button">@drawable/radio_selected</item>
    </style>

    <style name="AppBaseTheme" parent="android:Theme.Light">

    </style>

    <!-- Application theme. -->
    <style name="AppTheme" parent="AppBaseTheme">
        <!-- All customizations that are NOT specific to a particular API-level can go here. -->

        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
    </style>
</resources>

logcat

    FATAL EXCEPTION: main
Process: abc.kayraas.com.allaboutcity, PID: 15728
java.lang.RuntimeException: Unable to start activity ComponentInfo{abc.kayraas.com.allaboutcity/abc.kayraas.com.allaboutcity.MainListingActivity}: java.lang.NullPointerException
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2404)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2464)
    at android.app.ActivityThread.access$900(ActivityThread.java:172)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1308)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:146)
    at android.app.ActivityThread.main(ActivityThread.java:5653)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:515)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107)
    at dalvik.system.NativeStart.main(Native Method)
 Caused by: java.lang.NullPointerException
    at abc.kayraas.com.allaboutcity.MainListingActivity.onCreate(MainListingActivity.java:37)
    at android.app.Activity.performCreate(Activity.java:5541)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2368)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2464) 
    at android.app.ActivityThread.access$900(ActivityThread.java:172) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1308) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:146) 
    at android.app.ActivityThread.main(ActivityThread.java:5653) 
    at java.lang.reflect.Method.invokeNative(Native Method) 

<application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".SlashActivity"
            android:theme="@android:style/Theme.Holo.Light.DarkActionBar">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

style.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.view.ViewPager
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/pager"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

<resources>


    <style name="MyRadioButtonStyle" parent="@android:style/Widget.CompoundButton.RadioButton">
        <item name="android:button">@drawable/radio_selected</item>
    </style>

    <style name="AppBaseTheme" parent="android:Theme.Light">

    </style>

    <!-- Application theme. -->
    <style name="AppTheme" parent="AppBaseTheme">
        <!-- All customizations that are NOT specific to a particular API-level can go here. -->

        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
    </style>
</resources>

@可拖动/收音机已选择
@颜色/原色
@颜色/原色暗
@颜色/颜色重音

清单

    FATAL EXCEPTION: main
Process: abc.kayraas.com.allaboutcity, PID: 15728
java.lang.RuntimeException: Unable to start activity ComponentInfo{abc.kayraas.com.allaboutcity/abc.kayraas.com.allaboutcity.MainListingActivity}: java.lang.NullPointerException
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2404)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2464)
    at android.app.ActivityThread.access$900(ActivityThread.java:172)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1308)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:146)
    at android.app.ActivityThread.main(ActivityThread.java:5653)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:515)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107)
    at dalvik.system.NativeStart.main(Native Method)
 Caused by: java.lang.NullPointerException
    at abc.kayraas.com.allaboutcity.MainListingActivity.onCreate(MainListingActivity.java:37)
    at android.app.Activity.performCreate(Activity.java:5541)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1093)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2368)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2464) 
    at android.app.ActivityThread.access$900(ActivityThread.java:172) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1308) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:146) 
    at android.app.ActivityThread.main(ActivityThread.java:5653) 
    at java.lang.reflect.Method.invokeNative(Native Method) 

<application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".SlashActivity"
            android:theme="@android:style/Theme.Holo.Light.DarkActionBar">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

试试这个：

actionBar=getSupportActionBar

Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    getSupportActionBar().setTitle("Home");

//在AppTheme中的styles.xml中，更新为

 <style name="AppTheme" parent="Theme.AppCompat.NoActionBar">

//在xml中，在顶部写下以下内容：

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

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

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

这是您当前的代码：

  <style name="AppTheme" parent="AppBaseTheme">
    <!-- All customizations that are NOT specific to a particular API-level can go here. -->

    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>
</style>

@颜色/原色
@颜色/原色暗
@颜色/颜色重音

而是写下：

 <style name="AppTheme" parent="Theme.AppCompat.NoActionBar">
    <!-- Customize your theme here. -->
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>
</style>

@颜色/原色
@颜色/原色暗
@颜色/颜色重音

试试这段代码<代码>ActionBar ActionBar=getSupportActionBar（）

在您的style.xml中更改此行：

<style name="AppBaseTheme" parent="android:Theme.Light">

到

您在清单中使用的主题类型。不推荐使用操作栏。如果还希望使用支持操作栏的主题，请使用getSupportActionBar（）方法。看看这个问题@Abhishek-我已经发布了我的清单和样式。你能帮我吗？@JigarMakwana post

activity\u listing.xm

@JigarMakwana你发布的布局标题是main\u listing.xml，但你的活动使用的是activity\u listing.xml。这是一个错误吗？当我使用getSupportActionBar时，它会给出错误。（使用getter方法）。请检查此链接：uska hi Reference liya he bhai。。！！！请帮我找到“工具栏”，你必须在xml中创建一个工具栏。Rushi-你能帮我吗？怎么做？它说不能在主题中解析。：（而且当我设置它时，也会给我红线错误。请在这里粘贴你的风格