setSupportActionBar（）が何らかの理由で私のアプリの機能不全

Question

を作り、私はラインsetSupportActionBar（MyToolBarVariable）を入れたとき...それは私のGenymotionエミュレータに移行..しかし、それはアプリを開いたとき、それは言う：

Unfourtuanetlyあなたが他の人を見るために必要がある場合は教えてください。.. ImはMainActivity.javaファイルを投稿しよう...いただきました！ここでの問題...「APPNAMEは」

を立ち止まったが、私は削除した場合setSupportActionBar（）すべてが正常に動作します私は以下の通りです。助けてくれてありがとう！

package com.example.amanuel.zoo4; 

import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.support.v7.widget.Toolbar; 

public class MainActivity extends AppCompatActivity { 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
     setSupportActionBar(toolbar); 
     setContentView(R.layout.activity_main); 
    } 


} 

ここはLOGCATです。エミュレータでアプリを押すと、

04-06 02:09:02.522 652-1011/? I/ActivityManager: START u0 {act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.example.amanuel.zoo4/.MainActivity (has extras)} from uid 10008 on display 0 
04-06 02:09:02.721 3360-3360/? I/art: Late-enabling -Xcheck:jni 
04-06 02:09:02.762 652-1021/? I/ActivityManager: Start proc 3360:com.example.amanuel.zoo4/u0a63 for activity com.example.amanuel.zoo4/.MainActivity 
04-06 02:09:02.815 652-667/? W/art: Long monitor contention event with owner method=void com.android.server.am.ActivityManagerService.activityPaused(android.os.IBinder) from ActivityManagerService.java:6439 waiters=1 for 136ms 
04-06 02:09:02.978 3360-3360/? W/System: ClassLoader referenced unknown path: /data/app/com.example.amanuel.zoo4-2/lib/x86 
04-06 02:09:03.170 3360-3360/? D/AndroidRuntime: Shutting down VM 
04-06 02:09:03.178 3360-3360/? E/AndroidRuntime: FATAL EXCEPTION: main 
               Process: com.example.amanuel.zoo4, PID: 3360 
               java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.amanuel.zoo4/com.example.amanuel.zoo4.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.CharSequence android.support.v7.widget.Toolbar.getTitle()' 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 'java.lang.CharSequence android.support.v7.widget.Toolbar.getTitle()' on a null object reference 
                at android.support.v7.internal.widget.ToolbarWidgetWrapper.<init>(ToolbarWidgetWrapper.java:94) 
                at android.support.v7.internal.widget.ToolbarWidgetWrapper.<init>(ToolbarWidgetWrapper.java:87) 
                at android.support.v7.internal.app.ToolbarActionBar.<init>(ToolbarActionBar.java:77) 
                at android.support.v7.app.AppCompatDelegateImplV7.setSupportActionBar(AppCompatDelegateImplV7.java:198) 
                at android.support.v7.app.AppCompatActivity.setSupportActionBar(AppCompatActivity.java:96) 
                at com.example.amanuel.zoo4.MainActivity.onCreate(MainActivity.java:13) 
                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)  
04-06 02:09:03.193 652-1021/? W/ActivityManager: Force finishing activity com.example.amanuel.zoo4/.MainActivity 
04-06 02:09:03.500 652-1021/? I/WindowManager: Screenshot max retries 4 of Token{75d8954 ActivityRecord{722f0a7 u0 com.example.amanuel.zoo4/.MainActivity t42 f}} appWin=Window{450aeec u0 Starting com.example.amanuel.zoo4} drawState=1 
04-06 02:09:03.514 652-652/? W/art: Long monitor contention event with owner method=void com.android.server.am.ActivityManagerService.crashApplication(com.android.server.am.ProcessRecord, android.app.ApplicationErrorReport$CrashInfo) from ActivityManagerService.java:12502 waiters=0 for 299ms 
04-06 02:09:03.639 652-666/? W/art: Long monitor contention event with owner method=void com.android.server.am.ActivityManagerService.crashApplication(com.android.server.am.ProcessRecord, android.app.ApplicationErrorReport$CrashInfo) from ActivityManagerService.java:12502 waiters=1 for 216ms 
04-06 02:09:03.640 652-652/? W/art: Long monitor contention event with owner method=void com.android.server.am.ActivityManagerService$UiHandler.handleMessage(android.os.Message) from ActivityManagerService.java:1397 waiters=1 for 111ms 
04-06 02:09:03.814 652-1641/? I/OpenGLRenderer: Initialized EGL, version 1.4 
04-06 02:09:04.021 652-666/? W/ActivityManager: Activity pause timeout for ActivityRecord{722f0a7 u0 com.example.amanuel.zoo4/.MainActivity t42 f} 
04-06 02:09:04.129 652-1641/? W/EGL_emulation: eglSurfaceAttrib not implemented 
04-06 02:09:04.130 652-1641/? W/OpenGLRenderer: Failed to set EGL_SWAP_BEHAVIOR on surface 0xd60610a0, error=EGL_SUCCESS 
04-06 02:09:04.198 652-667/? I/Choreographer: Skipped 32 frames! The application may be doing too much work on its main thread. 
04-06 02:09:04.303 652-981/? I/ActivityManager: Killing 1792:com.android.keychain/1000 (adj 15): empty for 3078s 
04-06 02:09:04.763 652-668/? E/BluetoothAdapter: Bluetooth binder is null 
04-06 02:09:04.825 652-667/? I/Choreographer: Skipped 37 frames! The application may be doing too much work on its main thread. 
04-06 02:09:07.697 3360-3360/? I/Process: Sending signal. PID: 3360 SIG: 9 
04-06 02:09:07.732 652-679/? I/ActivityManager: Process com.example.amanuel.zoo4 (pid 3360) has died 
04-06 02:09:07.771 652-1641/? E/Surface: getSlotFromBufferLocked: unknown buffer: 0xde8f0df0 
04-06 02:09:07.844 652-1641/? D/OpenGLRenderer: endAllStagingAnimators on 0xda3b2380 (RippleDrawable) with handle 0xdc57f670 
04-06 02:09:07.852 652-652/? W/art: Long monitor contention event with owner method=void android.view.WindowManagerGlobal.removeView(android.view.View, boolean) from WindowManagerGlobal.java:349 waiters=0 for 102ms 
04-06 02:09:07.854 652-1164/? W/InputMethodManagerService: Window already focused, ignoring focus gain of: com.android.internal.view.IInputMethodClient$Stub$Proxy@bc8dc8f attribute=null, token = android.os.BinderProxy@4b639cb 
04-06 02:09:08.200 652-671/? W/AppOps: Finishing op nesting under-run: uid 1000 pkg android code 24 time=0 duration=0 nesting=0 
04-06 02:09:12.630 308-647/? W/AudioFlinger: write blocked for 9842 msecs, 14 delayed writes, thread 0xf1e00000 
04-06 02:09:18.081 100-100/? D/Genyd: Received Set Clipboard 
04-06 02:09:18.081 100-100/? D/Genymotion: Received Set Clipboard 

Answer 1

ツールバーをインスタンス化しようとする前にsetContentView(R.layout.activity_main);を入れてみてください。