View.findViewById(int)' on a null object reference

0
votes

I'm new to AndroidStudio, and I'm working on MySQL connection with JDBC lib.

I have no error with compiling but when I run my app, I'm getting this error:

appname has stopped.

Thank you.

E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.root14.yourapp, PID: 6784 java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference at com.example.root14.yourapp.tab1.onCreateView(tab1.java:25) at android.support.v4.app.Fragment.performCreateView(Fragment.java:2080) at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1108) at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1290) at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:801) at android.support.v4.app.FragmentManagerImpl.execSingleAction(FragmentManager.java:1638) at android.support.v4.app.BackStackRecord.commitNowAllowingStateLoss(BackStackRecord.java:679) at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:143) at android.support.v4.view.ViewPager.populate(ViewPager.java:1240) at android.support.v4.view.ViewPager.populate(ViewPager.java:1088) at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1614) at android.view.View.measure(View.java:19731) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6120) at android.support.design.widget.CoordinatorLayout.onMeasureChild(CoordinatorLayout.java:700) at android.support.design.widget.HeaderScrollingViewBehavior.onMeasureChild(HeaderScrollingViewBehavior.java:90) at android.support.design.widget.AppBarLayout$ScrollingViewBehavior.onMeasureChild(AppBarLayout.java:1364) at android.support.design.widget.CoordinatorLayout.onMeasure(CoordinatorLayout.java:765) at android.view.View.measure(View.java:19731) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6120) at android.widget.FrameLayout.onMeasure(FrameLayout.java:185) at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135) at android.view.View.measure(View.java:19731) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6120) at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464) at android.widget.LinearLayout.measureVertical(LinearLayout.java:758) at android.widget.LinearLayout.onMeasure(LinearLayout.java:640) at android.view.View.measure(View.java:19731) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6120) at android.widget.FrameLayout.onMeasure(FrameLayout.java:185) at android.view.View.measure(View.java:19731) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6120) at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464) at android.widget.LinearLayout.measureVertical(LinearLayout.java:758) at android.widget.LinearLayout.onMeasure(LinearLayout.java:640) at android.view.View.measure(View.java:19731) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6120) at android.widget.FrameLayout.onMeasure(FrameLayout.java:185) at com.android.internal.policy.DecorView.onMeasure(DecorView.java:687) at android.view.View.measure(View.java:19731) at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2271) at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1358) at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1607) at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1246) at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6301) at android.view.Choreographer$CallbackRecord.run(Choreographer.java:871) at android.view.Choreographer.doCallbacks(Choreographer.java:683) at android.view.Choreographer.doFrame(Choreographer.java:619) at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:857) at android.os.Handler.handleCallback(Handler.java:751) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:154) at android.app.ActivityThread.main(ActivityThread.java:6077) at java.lang.reflect.Method.invoke(Native Method) 04-08 22:01:09.999 6784-6784/com.example.root14.yourapp E/AndroidRuntime: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)

1
javaandroidnullpointerexceptionmysql-connector
Generally speaking, Android should not use direct JDBC connection for security and performance reasons. – OneCricketeer
post some code, those two answers should be a comment! as is , the error range is too large – Remario
JDBC is for vanilla java, it is not optimized for android operating system, there is sqlite, but i recommend a faster approach such realm which is nosql. transactions are based on object relational mappings. – Remario
Possible duplicate of What is a NullPointerException, and how do I fix it? – natario

1 Answers

3
votes

java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference

Did you tried to debug and check the app for above Null pointer exception?

It seems code is trying to access element which is not present in the content_main.xml or activity_main.xml. Hope this helps.