小编Lem*_*try的帖子

我一直坚持这个,检查官方指导等.任何教程/从ActionBar更改为ActionBarCompat的步骤(对于工具栏和旧版本的支持？我已导入appcompat-v7:21.0.+,试着

getSupportActionBar(); 和

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

setSupportActionBar(toolbar);

将主题更改为appcompat主题样式...任何常见的错误要注意或想法？

继续遇到这种错误:

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) …