Android:如何/教程将 ActionBar 更改为 ActionBarCompat(工具栏)？

Question

我一直坚持这一点，查看了官方指南等。任何教程/从 ActionBar 更改为 ActionBarCompat 的步骤是什么(对于旧版本的工具栏和支持？我已经导入了 appcompat-v7:21.0 .+, 尝试过

getSupportActionBar(); 和

Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar_actionbar);

setSupportActionBar(toolbar);

在样式中将主题更改为 appcompat 主题...有任何需要注意的常见错误或想法吗？

不断出现这种错误:

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.battery.plusfree/com.battery.plusfree.MainCollectionActivity}: java.lang.NullPointerException
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2212)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2271)
        at android.app.ActivityThread.access$800(ActivityThread.java:144)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1205)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:136)
        at android.app.ActivityThread.main(ActivityThread.java:5146)
        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:732)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:566)
        at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:132)
        at dalvik.system.NativeStart.main(Native Method)
 Caused by: java.lang.NullPointerException
        at com.battery.plusfree.MainCollectionActivity.onCreate(MainCollectionActivity.java:133)
        at android.app.Activity.performCreate(Activity.java:5231)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2169)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2271)
            at android.app.ActivityThread.access$800(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1205)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5146)
            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:732)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:566)
            at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:132)
            at dalvik.system.NativeStart.main(Native Method)

Answer 1

我从我的应用程序中了解到，您不能同时使用工具栏和操作栏。所以这可能是你的问题所在，但我不确定，因为你没有发布你的代码，但使用 styles.xml 文件你必须指定或者像这样:

<style name="AppTheme.Base" parent="Theme.AppCompat">
    <item name="colorPrimary">@color/mycolorprimary</item>
    <item name="colorPrimaryDark">@color/mycolorprimarydark</item>
    <item name="android:windowNoTitle">true</item>
    <item name="windowActionBar">false</item>
</style>

Activity .xml:

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

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:custom="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <!-- dont use this if you only want to use the actionbar instead -->

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_height="wrap_content"
        android:layout_width="match_parent"
        android:elevation="5dp"
        android:minHeight="?attr/actionBarSize"
        android:background="?attr/colorPrimary" />

</LinearLayout>

Activity .java:

    public class MyActivity extends ActionBarActivity {

       Toolbar mToolbar;

       public void onCreate(Bundle savedInstanceState) {

          // configure toolbar stuff
          setSupportActionBar(mToolbar);

          // or if you don't want to use the toolbar
          // then change the style values accordingly
          // and then you can run getSupportActionBar() instead

       }

    }

引用:here ..希望这有帮助!