java - 在 onCreateView 方法之外的 Fragment Activity 中使用 Edittext

Question

正如标题所说，我需要获取 fragment Activity 中包含的 editText 的值，它是 ViewPager 的一部分；到目前为止，我已经尝试了所有方法，并且我已经了解，只需在充气后传递 Activity 的当前 View 即可访问 xml 项目，这就是我所做的。但是我需要包含包含的值在用户填写后的编辑文本中，特别是在按下“保存”按钮后；在程序执行期间，当我尝试获取包含的文本时，我收到此错误:“java.lang.NullPointerException:尝试调用虚拟方法'android.text.Editable android.widget.EditText.getText ()' 在空对象引用上”抱歉这个愚蠢的问题，我是 Android 编程新手，我很感谢我能得到的所有帮助这是 fragment Activity 的代码:

public class Monday extends android.support.v4.app.Fragment{
EditText[] subjects = new EditText[6];
EditText[] classes = new EditText[6];

private OnFragmentInteractionListener mListener;

    public Monday() {
        // Required empty public constructor
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        ScrollView scrollView = (ScrollView)inflater.inflate(R.layout.fragment_monday, container, false);
        //some code

        subjects[0] = (EditText) scrollView.findViewById(R.id.editTextMateria1);
        subjects[1] = (EditText) scrollView.findViewById(R.id.editTextMateria2);
        subjects[2] = (EditText) scrollView.findViewById(R.id.editTextMateria3);
        subjects[3] = (EditText) scrollView.findViewById(R.id.editTextMateria4);
        subjects[4] = (EditText) scrollView.findViewById(R.id.editTextMateria5);
        subjects[5] = (EditText) scrollView.findViewById(R.id.editTextMateria6);


        classes[0] = (EditText) scrollView.findViewById(R.id.editTextClasse1);
        classes[1] = (EditText) scrollView.findViewById(R.id.editTextClasse2);
        classes[2] = (EditText) scrollView.findViewById(R.id.editTextClasse3);
        classes[3] = (EditText) scrollView.findViewById(R.id.editTextClasse4);
        classes[4] = (EditText) scrollView.findViewById(R.id.editTextClasse5);
        classes[5] = (EditText) scrollView.findViewById(R.id.editTextClasse6);
        return scrollView;
        //return inflater.inflate(R.layout.fragment_monday, container, false);
    }

    // TODO: Rename method, update argument and hook method into UI event
    public void onButtonPressed(Uri uri) {
        if (mListener != null) {
            mListener.onFragmentInteraction(uri);
        }
    }

    @Override
    public void onDetach() {
        super.onDetach();
        mListener = null;
    }

    public interface OnFragmentInteractionListener {
        // TODO: Update argument type and name
        public void onFragmentInteraction(Uri uri);
    }

    public String[] calculateDay(){


        String s = "";
        for(int i=1;i<subjects.length;i++){
            s += subjects[i].getText().toString()+"-"+classes[i].getText().toString()+";";
        }
        String[] monday = new String[6];

        monday = s.split(";");
        return monday;

    }
}

这是生成错误的部分:

   s += subjects[i].getText().toString()+"-"+classes[i].getText().toString()+";";

这是生成 ViewPager 的“mainactivity”的代码(在其上处理按下保存的按钮):

public class CustomTimetables extends FragmentActivity implements NoticeDialogFragment.NoticeDialogListener{

    public static String classname = "";
    ViewPager viewPager = null;

    private MyAdapter2 mAdapter;

    ViewPager Tab;
    MyAdapter2 TabAdapter;
    ActionBar actionBar;
    PagerSlidingTabStrip tabs;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getWindow().requestFeature(Window.FEATURE_ACTION_BAR);
        setContentView(R.layout.activity_custom_timetables);

        tabs = (PagerSlidingTabStrip) findViewById(R.id.tabs);
        Tab = (ViewPager) findViewById(R.id.pager);
        TabAdapter = new MyAdapter2(getSupportFragmentManager());

        Tab.setAdapter(TabAdapter);
        tabs.setViewPager(Tab);
        Toast.makeText(  getApplicationContext(),
                "Inserisci l'orario nelle caselle, lasciale vuote se le lezioni terminano prima ",
                Toast.LENGTH_LONG
        ).show();



    }



    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_custom_timetables, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {

        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }


    public void onSaveTimetable(View v){
        DialogFragment dialog = new NoticeDialogFragment();
        dialog.show(this.getSupportFragmentManager(), "insert_class");
    }

    public void onDialogPositiveClick(DialogFragment dialog) {
        String timetable = "Orario;Lunedi;Martedi;Mercoledi;Giovedi;Venerdi;Sabato;\n08:00;";


        String[] monday = new String[6];
        Monday m = new Monday();
        monday  = m.calculateDay();

        for(int i = 0; i<6; i++){
            timetable += monday[i]+";";



            switch(i){
                case 0: timetable +="\n";break;
                case 1 : timetable +="\n09:00;";break;
                case 2 : timetable +="\n10:00;";break;
                case 3 : timetable +="\n11:05;";break;
                case 4 : timetable +="\n12:00;";break;
                case 5 : timetable +="\n12:50;";break;
            }

        }

    }

    @Override
    public void onDialogNegativeClick(DialogFragment dialog) {

    }
}

class MyAdapter2 extends FragmentStatePagerAdapter
{

    public MyAdapter2(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int i) {
        Fragment fragment = null;
        if(i==0){
            fragment = new Monday();
        }
        if(i==1){
            fragment = new Tuesday();
        }
        if(i==2){
            fragment = new Wednesday();
        }
        if(i==3){
            fragment = new Thursday();
        }
        if(i==4){
            fragment = new Friday();
        }
        if(i==5){
            fragment = new Saturday();
        }
        return fragment;
    }

    @Override
    public int getCount() {
        return 6;
    }

    @Override
    public CharSequence getPageTitle(int position) {

        if(position == 0){
            return "Lunedi";
        }
        if(position == 1){
            return "Martedi";
        }
        if(position == 2){
            return "Mercoledi";
        }
        if(position == 3){
            return "Giovedi";
        }
        if(position == 4){
            return "Venerdi";
        }
        if(position == 5){
            return "Sabato";
        }
        return null;
    }


}

这是日志猫:

    06-09 19:29:16.172  24414-24443/com.progettostage.nick__000.timetablesapp D/OpenGLRenderer﹕ Use EGL_SWAP_BEHAVIOR_PRESERVED: true
06-09 19:29:16.187  24414-24414/com.progettostage.nick__000.timetablesapp D/Atlas﹕ Validating map...
06-09 19:29:16.250  24414-24443/com.progettostage.nick__000.timetablesapp I/Adreno-EGL﹕ <qeglDrvAPI_eglInitialize:379>: QUALCOMM Build: 01/15/15, ab0075f, Id3510ff6dc
06-09 19:29:16.252  24414-24443/com.progettostage.nick__000.timetablesapp I/OpenGLRenderer﹕ Initialized EGL, version 1.4
06-09 19:29:16.290  24414-24443/com.progettostage.nick__000.timetablesapp D/OpenGLRenderer﹕ Enabling debug mode 0
06-09 19:32:20.725  24414-24443/com.progettostage.nick__000.timetablesapp V/RenderScript﹕ Application requested CPU execution
06-09 19:32:20.738  24414-24443/com.progettostage.nick__000.timetablesapp V/RenderScript﹕ 0xb83ba0b8 Launching thread(s), CPUs 4
06-09 19:32:38.415  24414-24414/com.progettostage.nick__000.timetablesapp D/AndroidRuntime﹕ Shutting down VM
06-09 19:32:38.422  24414-24414/com.progettostage.nick__000.timetablesapp E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.progettostage.nick__000.timetablesapp, PID: 24414
    java.lang.NullPointerException: Attempt to invoke virtual method 'android.text.Editable android.widget.EditText.getText()' on a null object reference
            at com.progettostage.nick__000.timetablesapp.Monday.calculateDay(Monday.java:111)
            at com.progettostage.nick__000.timetablesapp.CustomTimetables.onDialogPositiveClick(CustomTimetables.java:111)
            at com.progettostage.nick__000.timetablesapp.NoticeDialogFragment$2.onClick(NoticeDialogFragment.java:33)
            at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:162)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5254)
            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:903)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

这只是处理对话框的类，我认为它与它没有任何关系，但安全总比抱歉好..

public class NoticeDialogFragment extends DialogFragment {


    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
        // Get the layout inflater
        LayoutInflater inflater = getActivity().getLayoutInflater();
        final View view = inflater.inflate(R.layout.dialog_classinput, null);
        // Inflate and set the layout for the dialog
        // Pass null as the parent view because its going in the dialog layout
        builder.setView(view)
                // Add action buttons
                .setTitle("Inserisci nome classe")
                .setPositiveButton("Ok", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int id) {
                        EditText et = (EditText)view.findViewById(R.id.classname22);
                        CustomTimetables.classname = et.getText().toString();
                        // Send the positive button event back to the host activity
                        mListener.onDialogPositiveClick(NoticeDialogFragment.this);
                    }
                })
                .setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                        dialog.dismiss();
                    }
                });
        return builder.create();
    }


    public interface NoticeDialogListener {
        public void onDialogPositiveClick(DialogFragment dialog);
        public void onDialogNegativeClick(DialogFragment dialog);
    }


    NoticeDialogListener mListener;


    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        // Verify that the host activity implements the callback interface
        try {
            // Instantiate the NoticeDialogListener so we can send events to the host
            mListener = (NoticeDialogListener) activity;
        } catch (ClassCastException e) {
            // The activity doesn't implement the interface, throw exception
            throw new ClassCastException(activity.toString()
                    + " must implement NoticeDialogListener");
        }
    }

}

这也是Monday.xml(最后因为太长而不得不剪掉一些部分，但很简单，就这样一直到editTextMateria6和editTextClasse6):

<ScrollView
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="vertical">
<RelativeLayout  android:layout_width="match_parent"
    android:layout_height="wrap_content"
    tools:context=".Monday"

        >


    <TextView
        android:gravity="center"
        android:layout_width="match_parent"
        android:layout_height="58dp"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="8:00-9:00"
        android:id="@+id/PrimaOra"
        android:textSize="25dp"

        android:layout_gravity="center_horizontal|bottom"
        android:layout_marginLeft="16dp"
        android:layout_marginRight="16dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="50dp" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Materia"
        android:id="@+id/materia1"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="115dp" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="textPersonName"
        android:ems="10"
        android:id="@+id/editTextMateria1"
        android:layout_marginTop="160dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Classe"
        android:id="@+id/classe1"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="225dp" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="textPersonName"
        android:text=""
        android:ems="10"
        android:id="@+id/editTextClasse1"
        android:layout_marginTop="270dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" />
-----------------------------------------------------

    <TextView
        android:gravity="center"
        android:layout_width="match_parent"
        android:layout_height="58dp"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="9:00-10:00"
        android:id="@+id/SecondaOra"
        android:textSize="25dp"
        android:layout_gravity="center_horizontal|bottom"
        android:layout_marginLeft="16dp"
        android:layout_marginRight="16dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="325dp" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Materia"
        android:id="@+id/materia2"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="390dp" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="textPersonName"
        android:text=""
        android:ems="10"
        android:id="@+id/editTextMateria2"
        android:layout_marginTop="435dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" />
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Classe"
        android:id="@+id/classe2"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="500dp" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="textPersonName"
        android:text=""
        android:ems="10"
        android:id="@+id/editTextClasse2"
        android:layout_marginTop="545dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"/>
        -----------------------------------------

    <TextView
        android:gravity="center"
        android:layout_width="match_parent"
        android:layout_height="58dp"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="10:00-10:50"
        android:id="@+id/TerzaOra"
        android:textSize="25dp"
        android:layout_gravity="center_horizontal|bottom"
        android:layout_marginLeft="16dp"
        android:layout_marginRight="16dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="600dp" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Materia"
        android:id="@+id/materia3"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="665dp" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="textPersonName"
        android:text=""
        android:ems="10"
        android:id="@+id/editTextMateria3"
        android:layout_marginTop="710dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" />
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Classe"
        android:id="@+id/classe3"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="775dp" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="textPersonName"
        android:text=""
        android:ems="10"
        android:id="@+id/editTextClasse3"
        android:layout_marginTop="825dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"/>
    -----------------------------------------
    <TextView
        android:gravity="center"
        android:layout_width="match_parent"
        android:layout_height="58dp"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="11:05-12:00"
        android:id="@+id/QuartaOra"
        android:textSize="25dp"
        android:layout_gravity="center_horizontal|bottom"
        android:layout_marginLeft="16dp"
        android:layout_marginRight="16dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="875dp" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Materia"
        android:id="@+id/materia4"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="940dp" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="textPersonName"
        android:text=""
        android:ems="10"
        android:id="@+id/editTextMateria4"
        android:layout_marginTop="985dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" />
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Classe"
        android:id="@+id/classe4"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="1050dp" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="textPersonName"
        android:text=""
        android:ems="10"
        android:id="@+id/editTextClasse4"
        android:layout_marginTop="1095dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"/>
    ------------------------------------------------
    <TextView
        android:gravity="center"
        android:layout_width="match_parent"
        android:layout_height="58dp"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="12:00-12:50"
        android:id="@+id/QuintaOra"
        android:textSize="25dp"
        android:layout_gravity="center_horizontal|bottom"
        android:layout_marginLeft="16dp"
        android:layout_marginRight="16dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="1150dp" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Materia"
        android:id="@+id/materia5"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="1215dp" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="textPersonName"
        android:text=""
        android:ems="10"
        android:id="@+id/editTextMateria5"
        android:layout_marginTop="1260dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true" />
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Classe"
        android:id="@+id/classe5"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="1325dp" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:inputType="textPersonName"
        android:text=""
        android:ems="10"
        android:id="@+id/editTextClasse5"
        android:layout_marginTop="1380dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"/>
    ----------------------------------------------
    <TextView
        android:gravity="center"
        android:layout_width="match_parent"
        android:layout_height="58dp"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="12:50-13:40"
        android:id="@+id/SestaOra"
        android:textSize="25dp"
        android:layout_gravity="center_horizontal|bottom"
        android:layout_marginLeft="16dp"
        android:layout_marginRight="16dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="1435dp" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text="Materia"
        android:id="@+id/materia6"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="1500dp" />



    <Button
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:width="400dp"
        android:height="70dp"
        android:onClick="onSaveTimetable"
        android:text="Salva"
        android:layout_marginTop="1700dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        />


</RelativeLayout>
</ScrollView>

更新好吧，我添加了几行，所以也许更清楚问题是什么..

  String sub1 = subjects[0].getText().toString();
            String classr1 = classes[0].getText().toString();
            for(int i=0;i<subjects.length;i++){
                s += subjects[i].getText().toString()+"-"+classes[i].getText().toString()+";";
            }

如果我这样设置，我会在 sub1 行得到同样的错误，因为在这样的方法中，我无法传递 View 或膨胀它，就像我在 oncreateview 上所做的那样，它无论我做什么操作，都可以正常工作。问题是，在用户在其中放入一些内容后，我需要这些编辑文本。我希望我说得更清楚了，我感谢我仍然得到的所有帮助，我'我想指出的是，我已经尝试了这里的每一个解决方案，尽管我没有全部回复

Answer 1

数组索引从0开始。访问数组时请确保使用正确的索引值。