了java.lang.RuntimeException：无法启动活动ComponentInfo {..}显示java.lang.NullPointerException

我想添加一些数据sqlite的DY fragmnet.but当我运行它给这个错误代码..了java.lang.RuntimeException：无法启动活动ComponentInfo {..}显示java.lang.NullPointerException

java.lang.RuntimeException: Unable to start activity ComponentInfo{codes.project.sameera.o_project/codes.project.sameera.o_project.Indi_Add_Details_menu}: java.lang.NullPointerException

我可以通过此代码将数据添加到sqlite而不使用Fragment.but但是当我将我的类转换为Fragmnet时，会发生这种情况。

我该如何解决这个问题..？

这是我Fragment_addStudentDetails类

public class Fragment_addStudentDetails extends Fragment implements View.OnClickListener { 
EditText fName,mName, Address, sName, hNo, mNo, presentSpo; 


DatabaseAdapter databaseHelper; 
Button btnAdd; 
Button btnView; 

@Override 
public View onCreateView(LayoutInflater inflater, 
         ViewGroup container, Bundle savedInstanceState) { 
    View view=inflater.inflate(R.layout.fragment_add_student_details,container,false); 

    fName=(EditText) view.findViewById(R.id.editTextfname); 
    mName=(EditText) view.findViewById(R.id.editTextmName); 
    Address = (EditText) view.findViewById(R.id.editTextAdd); 
    sName = (EditText) view.findViewById(R.id.editTextsure); 
    hNo = (EditText) view.findViewById(R.id.editTexttpH); 
    mNo = (EditText) view.findViewById(R.id.editTextTPM); 
    presentSpo = (EditText) view.findViewById(R.id.editTextPS); 

    btnAdd = (Button) view.findViewById(R.id.btnAdd); 
    btnView = (Button) view.findViewById(R.id.btnView); 
    btnAdd.setOnClickListener(this); 
    btnView.setOnClickListener(this); 
    databaseHelper = new DatabaseAdapter(getActivity()); 

    return view; 
} 
@Override 
public void onClick(View view) { 
    switch (view.getId()) { 
     case R.id.btnAdd: 
      addStudent(view); 
      break; 
     case R.id.btnView: 
      viewDetails(view); 

      break; 

     default: 
      break; 
    } 
} 
public void addStudent(View view){ 
    String fname = fName.getText().toString(); 
    String mname = mName.getText().toString(); 
    String sname = sName.getText().toString(); 
    String address = Address.getText().toString(); 
    String TPhome = hNo.getText().toString(); 
    String TPmobile = mNo.getText().toString(); 
    String presentsport = presentSpo.getText().toString(); 

    long id= databaseHelper.insertData(fname, mname, sname, address, TPhome, TPmobile, presentsport); 
    if(id<0){ 
     Message.message(getActivity(),"Error inInsertiong Data"); 
    }else 
    { 
     Message.message(getActivity(),"Succecsfuly inserted to data"); 

    } 

} 

public void viewDetails(View view){ 
    String data = databaseHelper.getAllData(); 
    Message.message(getActivity(),data); 
}

}

日志猫

 java.lang.RuntimeException: Unable to start activity ComponentInfo{codes.project.sameera.o_project/codes.project.sameera.o_project.Indi_Add_Details_menu}: java.lang.NullPointerException 
     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195) 
     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245) 
     at android.app.ActivityThread.access$800(ActivityThread.java:135) 
     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196) 
     at android.os.Handler.dispatchMessage(Handler.java:102) 
     at android.os.Looper.loop(Looper.java:136) 
     at android.app.ActivityThread.main(ActivityThread.java:5017) 
     at java.lang.reflect.Method.invokeNative(Native Method) 
     at java.lang.reflect.Method.invoke(Method.java:515) 
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
     at dalvik.system.NativeStart.main(Native Method) 
Caused by: java.lang.NullPointerException 
     at codes.project.sameera.o_project.Fragment_addStudentDetails.onCreateView(Fragment_addStudentDetails.java:38) 
     at android.app.Fragment.performCreateView(Fragment.java:1700) 
     at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:890) 
     at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1062) 
     at android.app.BackStackRecord.run(BackStackRecord.java:684) 
     at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1447) 
     at android.app.Activity.performStart(Activity.java:5240) 
     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2168)

来源

2014-08-29 kosala

Fragment_addStudentDetails.java的第38行是什么？ – cygery 2014-08-29 15:29:13

@cygery btnAdd.setOnClickListener（this）;此方法 – kosala 2014-08-29 15:32:44

然后'btnAdd'为空。请检查您的'fragment_add_student_details'布局是否包含带有'btnAdd' ID的Button。 – cygery 2014-08-29 15:35:00

btnAdd是null这会导致空指针异常的btnAdd.setOnClickListener(this)。这是因为fragment_add_student_details布局不包含View和btnAdd id。

来源

2014-08-29 15:45:30 cygery

了java.lang.RuntimeException：无法启动活动ComponentInfo {..}显示java.lang.NullPointerException

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