残念なことにあなたのアプリは動作を停止しました - アンドロイド

Question

ここはlogcatです。あなたのエラーメッセージが「NullPointerExceptionが」と言うと、CalcActivityのonCreate()メソッド内の何かによって引き起こされているようだ

04-30 11:52:45.716: E/AndroidRuntime(1430): FATAL EXCEPTION: main 
04-30 11:52:45.716: E/AndroidRuntime(1430): java.lang.RuntimeException: Unable to start activity ComponentInfo{my.calc/my.calc.CalcActivity}: java.lang.NullPointerException 
04-30 11:52:45.716: E/AndroidRuntime(1430):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956) 
04-30 11:52:45.716: E/AndroidRuntime(1430):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981) 
04-30 11:52:45.716: E/AndroidRuntime(1430):  at android.app.ActivityThread.access$600(ActivityThread.java:123) 
04-30 11:52:45.716: E/AndroidRuntime(1430):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147) 
04-30 11:52:45.716: E/AndroidRuntime(1430):  at android.os.Handler.dispatchMessage(Handler.java:99) 
04-30 11:52:45.716: E/AndroidRuntime(1430):  at android.os.Looper.loop(Looper.java:137) 
04-30 11:52:45.716: E/AndroidRuntime(1430):  at android.app.ActivityThread.main(ActivityThread.java:4424) 
04-30 11:52:45.716: E/AndroidRuntime(1430):  at java.lang.reflect.Method.invokeNative(Native Method) 
04-30 11:52:45.716: E/AndroidRuntime(1430):  at java.lang.reflect.Method.invoke(Method.java:511) 
04-30 11:52:45.716: E/AndroidRuntime(1430):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 
04-30 11:52:45.716: E/AndroidRuntime(1430):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 
04-30 11:52:45.716: E/AndroidRuntime(1430):  at dalvik.system.NativeStart.main(Native Method) 
04-30 11:52:45.716: E/AndroidRuntime(1430): Caused by: java.lang.NullPointerException 
04-30 11:52:45.716: E/AndroidRuntime(1430):  at my.calc.CalcActivity.onCreate(CalcActivity.java:47) 
04-30 11:52:45.716: E/AndroidRuntime(1430):  at android.app.Activity.performCreate(Activity.java:4465) 
04-30 11:52:45.716: E/AndroidRuntime(1430):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) 
04-30 11:52:45.716: E/AndroidRuntime(1430):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920) 
04-30 11:52:45.716: E/AndroidRuntime(1430):  ... 11 more 
04-30 11:53:59.415: E/AndroidRuntime(1445): FATAL EXCEPTION: main 
04-30 11:53:59.415: E/AndroidRuntime(1445): java.lang.RuntimeException: Unable to start activity ComponentInfo{my.calc/my.calc.CalcActivity}: java.lang.NullPointerException 
04-30 11:53:59.415: E/AndroidRuntime(1445):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956) 
04-30 11:53:59.415: E/AndroidRuntime(1445):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981) 
04-30 11:53:59.415: E/AndroidRuntime(1445):  at android.app.ActivityThread.access$600(ActivityThread.java:123) 
04-30 11:53:59.415: E/AndroidRuntime(1445):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147) 
04-30 11:53:59.415: E/AndroidRuntime(1445):  at android.os.Handler.dispatchMessage(Handler.java:99) 
04-30 11:53:59.415: E/AndroidRuntime(1445):  at android.os.Looper.loop(Looper.java:137) 
04-30 11:53:59.415: E/AndroidRuntime(1445):  at android.app.ActivityThread.main(ActivityThread.java:4424) 
04-30 11:53:59.415: E/AndroidRuntime(1445):  at java.lang.reflect.Method.invokeNative(Native Method) 
04-30 11:53:59.415: E/AndroidRuntime(1445):  at java.lang.reflect.Method.invoke(Method.java:511) 
04-30 11:53:59.415: E/AndroidRuntime(1445):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 
04-30 11:53:59.415: E/AndroidRuntime(1445):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 
04-30 11:53:59.415: E/AndroidRuntime(1445):  at dalvik.system.NativeStart.main(Native Method) 
04-30 11:53:59.415: E/AndroidRuntime(1445): Caused by: java.lang.NullPointerException 
04-30 11:53:59.415: E/AndroidRuntime(1445):  at my.calc.CalcActivity.onCreate(CalcActivity.java:47) 
04-30 11:53:59.415: E/AndroidRuntime(1445):  at android.app.Activity.performCreate(Activity.java:4465) 
04-30 11:53:59.415: E/AndroidRuntime(1445):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) 
04-30 11:53:59.415: E/AndroidRuntime(1445):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920) 
04-30 11:53:59.415: E/AndroidRuntime(1445):  ... 11 more 

Answer 1

を助けてください。で示されるように、そのクラスのためにあなたのコードの47行目に移動します：

04-30 11:53:59.415: E/AndroidRuntime(1445): Caused by: java.lang.NullPointerException 
04-30 11:53:59.415: E/AndroidRuntime(1445):  at my.calc.CalcActivity.onCreate(CalcActivity.java:47) 

あなたがまだ初期化されていないオブジェクトの呼び出しを行っていない、またはそれは基本的にnull値を持っていることを確認します。例えば、

List<String> strings; 
strings.get(0); // you should have done something like this one first: 
       // strings = new ArrayList<String>();