Android变成setContentView（）报错空指针异常

今天写一个例子，无缘无故报错空指针异常，定位错误竟然定位到了系统自动添加的setContentView（）中，从网上查到是因为我在布局文件中用到的一个控件View写用成了view，大写之后一切正常
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.jack.mycalculate, PID: 7687
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.jack.mycalculate/com.example.jack.mycalculate.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2585)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2659)
at android.app.ActivityThread.access$900(ActivityThread.java:188)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1521)
at android.os.Handler.dispatchMessage(Handler.java:111)
at android.os.Looper.loop(Looper.java:194)
at android.app.ActivityThread.main(ActivityThread.java:5714)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:984)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:779)
**Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference**
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:715)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
at android.view.LayoutInflater.parseInclude(LayoutInflater.java:890)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:802)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:809)
at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
at android.support.v7.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:469)
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:140)
at **com.example.jack.mycalculate.MainActivity.onCreate(MainActivity.java:26)**
at android.app.Activity.performCreate(Activity.java:6176)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1115)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2532)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2659)
at android.app.ActivityThread.access$900(ActivityThread.java:188)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1521)
at android.os.Handler.dispatchMessage(Handler.java:111)
at android.os.Looper.loop(Looper.java:194)
at android.app.ActivityThread.main(ActivityThread.java:5714)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:984)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:779)