在空对象引用上无效android.support.design.widget.FloatingActionButton.setOnClickListener(android.view.View $On

概述我已经开始开发应用程序,以某种方式我在DetailActivity.java类中出错了,我无法识别,请帮助我.publicclassPrayerDetailActivityextendsAppCompatActivity{@OverrideprotectedvoidonCreate(BundlesavedInstanceState){super.onCreate(savedInstanceState);s

我已经开始开发应用程序,以某种方式我在DetailActivity.java类中出错了,我无法识别,请帮助我.

public class PrayerDetailActivity extends AppCompatActivity {@OverrIDeprotected voID onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentVIEw(R.layout.activity_prayer_detail);    Toolbar toolbar = (Toolbar) findVIEwByID(R.ID.detail_toolbar);    setSupportActionbar(toolbar);    floatingActionbutton fab = (floatingActionbutton) findVIEwByID(R.ID.fab);    fab.setonClickListener(new VIEw.OnClickListener() {        @OverrIDe        public voID onClick(VIEw vIEw) {            Snackbar.make(vIEw, "Replace with your own detail action", Snackbar.LENGTH_LONG)                    .setAction("Action", null).show();        }    });    // Show the Up button in the action bar.    Actionbar actionbar = getSupportActionbar();    if (actionbar != null) {        actionbar.setdisplayHomeAsUpEnabled(true);    }    // savedInstanceState is non-null when there is fragment state    // saved from prevIoUs configurations of this activity    // (e.g. when rotating the screen from portrait to landscape).    // In this case, the fragment will automatically be re-added    // to its container so we don't need to manually add it.    // For more information, see the Fragments API guIDe at:    //    // http://developer.androID.com/guIDe/components/fragments.HTML    //    if (savedInstanceState == null) {        // Create the detail fragment and add it to the activity        // using a fragment transaction.        Bundle arguments = new Bundle();        arguments.putString(PrayerDetailFragment.ARG_ITEM_ID,                getIntent().getStringExtra(PrayerDetailFragment.ARG_ITEM_ID));        PrayerDetailFragment fragment = new PrayerDetailFragment();        fragment.setArguments(arguments);        getSupportFragmentManager().beginTransaction()                .add(R.ID.prayer_detail_container, fragment)                .commit();    }}@OverrIDepublic boolean onoptionsItemSelected(MenuItem item) {    int ID = item.getItemID();    if (ID == androID.R.ID.home) {        // This ID represents the Home or Up button. In the case of this        // activity, the Up button is shown. For        // more details, see the Navigation pattern on AndroID Design:        //        // http://developer.androID.com/design/patterns/navigation.HTML#up-vs-back        //        navigateUpTo(new Intent(this, PrayerListActivity.class));        return true;    }    return super.onoptionsItemSelected(item);}

}
   而我的xml文件是

<androID.support.design.Widget.AppbarLayout    androID:ID="@+ID/app_bar"    androID:layout_wIDth="match_parent"    androID:layout_height="@dimen/app_bar_height"    androID:fitsSystemwindows="true"    androID:theme="@style/themeOverlay.AppCompat.Dark.Actionbar">    <androID.support.design.Widget.CollapsingToolbarLayout        androID:ID="@+ID/toolbar_layout"        androID:layout_wIDth="match_parent"        androID:layout_height="match_parent"        androID:fitsSystemwindows="true"        app:contentScrim="?attr/colorPrimary"        app:layout_scrollFlags="scroll|exitUntilCollapsed"        app:toolbarID="@+ID/toolbar">        <androID.support.v7.Widget.Toolbar            androID:ID="@+ID/detail_toolbar"            androID:layout_wIDth="match_parent"            androID:layout_height="?attr/actionbarSize"            app:layout_collapseMode="pin"            app:popuptheme="@style/themeOverlay.AppCompat.light" />    </androID.support.design.Widget.CollapsingToolbarLayout></androID.support.design.Widget.AppbarLayout><androID.support.v4.Widget.nestedScrollVIEw    androID:ID="@+ID/prayer_detail_container"    androID:layout_wIDth="match_parent"    androID:layout_height="match_parent"    app:layout_behavior="@string/appbar_scrolling_vIEw_behavior" />

显示的错误是

02-09 23:39:45.711 8201-8220/com.jen.jennings.catholicprayers E/Surface: getSlotFromBufferLocked: unkNown buffer: 0xab79270002-09 23:39:54.364 8201-8220/com.jen.jennings.catholicprayers E/Surface: getSlotFromBufferLocked: unkNown buffer: 0xab79270002-09 23:39:55.868 8201-8201/com.jen.jennings.catholicprayers E/AndroIDRuntime: FATAL EXCEPTION: main                                                                                Process: com.jen.jennings.catholicprayers, PID: 8201                                              java.lang.RuntimeException: Unable to start activity ComponentInfo{com.jen.jennings.catholicprayers/com.jen.jennings.catholicprayers.PrayerDetailActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'voID androID.support.design.Widget.floatingActionbutton.setonClickListener(androID.vIEw.VIEw$OnClickListener)' on a null object reference                                                                            at androID.app.ActivityThread.performlaunchActivity(ActivityThread.java:2416)                                                                            at androID.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)                                                                            at androID.app.ActivityThread.-wrap11(ActivityThread.java)                                                                            at androID.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)                                                                            at androID.os.Handler.dispatchMessage(Handler.java:102)                                                                            at androID.os.Looper.loop(Looper.java:148)                                                                            at androID.app.ActivityThread.main(ActivityThread.java:5417)                                                                            at java.lang.reflect.Method.invoke(Native Method)                                                                            at com.androID.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)                                                                            at com.androID.internal.os.ZygoteInit.main(ZygoteInit.java:616)                                                                         Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'voID androID.support.design.Widget.floatingActionbutton.setonClickListener(androID.vIEw.VIEw$OnClickListener)' on a null object reference                                                                            at com.jen.jennings.catholicprayers.PrayerDetailActivity.onCreate(PrayerDetailActivity.java:29)                                                                            at androID.app.Activity.performCreate(Activity.java:6237)                                                                            at androID.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)                                                                            at androID.app.ActivityThread.performlaunchActivity(ActivityThread.java:2369)                                                                            at androID.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)                                                                             at androID.app.ActivityThread.-wrap11(ActivityThread.java)                                                                             at androID.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)                                                                             at androID.os.Handler.dispatchMessage(Handler.java:102)                                                                             at androID.os.Looper.loop(Looper.java:148)                                                                             at androID.app.ActivityThread.main(ActivityThread.java:5417)                                                                             at java.lang.reflect.Method.invoke(Native Method)                                                                             at com.androID.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)                                                                             at com.androID.internal.os.ZygoteInit.main(ZygoteInit.java:616) 

请帮我

解决方法:

在您的xml中,没有声明floatingActionbutton.

您正在尝试在onCreate()中使用它.

floatingActionbutton fab = (floatingActionbutton) findVIEwByID(R.ID.fab);

从您的活动的onCreate()方法中删除它,或者在xml布局中声明它.

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