了java.lang.RuntimeException：無法啓動活動ComponentInfo {..}顯示java.lang.NullPointerException

我想添加一些數據sqlite的DY fragmnet.but當我運行它給這個錯誤代碼..了java.lang.RuntimeException：無法啓動活動ComponentInfo {..}顯示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

我可以通過此代碼將數據添加到sqlite而不使用Fragment.but但是當我將我的類轉換爲Fragmnet時，會發生這種情況。

我該如何解決這個問題..？

這是我Fragment_addStudentDetails類

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); 
}

}

日誌貓

 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)

來源

2014-08-29 kosala

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

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

然後'btnAdd'爲空。請檢查您的'fragment_add_student_details'佈局是否包含帶有'btnAdd' ID的Button。 – cygery 2014-08-29 15:35:00

btnAdd是null這會導致空指針異常的btnAdd.setOnClickListener(this)。這是因爲fragment_add_student_details佈局不包含View和btnAdd id。

來源

2014-08-29 15:45:30 cygery

了java.lang.RuntimeException：無法啓動活動ComponentInfo {..}顯示java.lang.NullPointerException

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