在listview中动态生成edittext

Question

在我的片段中，我想显示从图库中选择的图像，并在列表视图中显示它们。每个列表视图项都包含图像的ImageView和标题的EditText。我在caption.setText（mAllCaptions.get（position））得到一个nullpointerexception，我想在一个名为mAllCaptions的字幕的ArrayList中给出一个默认标题，如Photo 1。任何想法

list_item_selected_image.xml

<ImageView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/selected_imageImageView"/>

<EditText
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/selected_imageCaptionEditText"
    android:background="@color/white"
    android:hint="@string/add_caption"
    android:textColorHint="@color/input_hint"
    android:textColor="@color/dark_grey"
    android:layout_marginTop="5dp"
    android:layout_marginBottom="5dp"
    android:padding="10dp"/>

    </LinearLayout>

内部类SelectedImagesAdapter

private class SelectedImagesAdapter extends ArrayAdapter<String>{


    public SelectedImagesAdapter(ArrayList<String> imagesArray){

        super(getActivity(),0,imagesArray);

        for (int i = 0; i < imagesArray.size(); i++) {

            int j = ++i;
            String defaultCaption  = "Photo " + j;
            mAllCaptions.add(defaultCaption);
        }
        notifyDataSetChanged();

    }//end constructor

    @Override
    public int getCount(){

        return mAllCaptions.size();
    }


    @Override
    public View getView(int position, View convertView, ViewGroup parent){

        //if we arent given a view inflate one
        //if there's no recycled view passed in inflate one

        if(convertView == null)
            convertView = getActivity()
                    .getLayoutInflater()
                    .inflate(R.layout.list_item_selected_image, null);

        //configure the view for this image
        String imagePath = getItem(position);
        Bitmap bitmap = BitmapFactory.decodeFile(imagePath);
        //get the screen width  at run time
        int screenWidth = DeviceDimensionsHelper.getDisplayWidth(getActivity());
        //load resized bitmap into an ImageView

        ImageView imageView = (ImageView)convertView.findViewById(R.id.selected_imageImageView);

        imageView.setImageBitmap(BitmapScaler.scaleToFitWidth(bitmap, screenWidth));

        EditText caption  =  (EditText)convertView.findViewById(R.id.selected_imageCaptionEditText);

        caption.setText(mAllCaptions.get(position));
        caption.setId(position);

        //update adapter once we finish editing
        caption.setOnFocusChangeListener(new View.OnFocusChangeListener() {
            @Override
            public void onFocusChange(View v, boolean hasFocus) {

                if (!hasFocus){
                    final int position = v.getId();
                    final EditText Caption = (EditText) v;
                    mAllCaptions.set(position, Caption.getText().toString());

                }


            }
        });

        return convertView;//return view object to the list view

    }
}//end private class ImagesAdapter

错误记录

java.lang.NullPointerException
at com.photos.android.photos.PhotosFragment$SelectedImagesAdapter.getView(PhotosFragment.java: 278)
at android.widget.AbsListView.obtainView(AbsListView.java: 2259)
at android.widget.ListView.makeAndAddView(ListView.java: 1813)
at android.widget.ListView.fillDown(ListView.java: 688)
at android.widget.ListView.fillDown(ListView.java: 667)
at android.widget.ListView.fillFromTop(ListView.java: 759)
at android.widget.ListView.layoutChildren(ListView.java: 1666)
at android.widget.AbsListView.onLayout(AbsListView.java: 2110)
at android.view.View.layout(View.java: 13947)
at android.view.ViewGroup.layout(ViewGroup.java: 4472)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java: 1687)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java: 1545)
at android.widget.LinearLayout.onLayout(LinearLayout.java: 1450)
at android.view.View.layout(View.java: 13947)
at android.view.ViewGroup.layout(ViewGroup.java: 4472)
at android.support.v4.view.ViewPager.onLayout(ViewPager.java: 1627)
at android.view.View.layout(View.java: 13947)
at android.view.ViewGroup.layout(ViewGroup.java: 4472)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java: 1687)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java: 1545)
at android.widget.LinearLayout.onLayout(LinearLayout.java: 1450)
at android.view.View.layout(View.java: 13947)
at android.view.ViewGroup.layout(ViewGroup.java: 4472)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java: 1687)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java: 1545)
at android.widget.LinearLayout.onLayout(LinearLayout.java: 1450)
at android.view.View.layout(View.java: 13947)
at android.view.ViewGroup.layout(ViewGroup.java: 4472)
at android.widget.FrameLayout.onLayout(FrameLayout.java: 460)
at android.view.View.layout(View.java: 13947)
at android.view.ViewGroup.layout(ViewGroup.java: 4472)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java: 1687)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java: 1545)
at android.widget.LinearLayout.onLayout(LinearLayout.java: 1450)
at android.view.View.layout(View.java: 13947)
at android.view.ViewGroup.layout(ViewGroup.java: 4472)
at android.widget.FrameLayout.onLayout(FrameLayout.java: 460)
at android.view.View.layout(View.java: 13947)
at android.view.ViewGroup.layout(ViewGroup.java: 4472)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java: 1687)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java: 1545)
at android.widget.LinearLayout.onLayout(LinearLayout.java: 1450)
at android.view.View.layout(View.java: 13947)
at android.view.ViewGroup.layout(ViewGroup.java: 4472)
at android.widget.FrameLayout.onLayout(FrameLayout.java: 460)
at android.view.View.layout(View.java: 13947)
at android.view.ViewGroup.layout(ViewGroup.java: 4472)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java: 1883)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java: 1704)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java: 1011)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java: 4244)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java: 725)
at android.view.Choreographer.doCallbacks(Choreographer.java: 555)
at android.view.Choreographer.doFrame(Choreographer.java: 525)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java: 711)
at android.os.Handler.handleCallback(Handler.java: 615)
at android.os.Handler.dispatchMessage(Handler.java: 92)
at android.os.Looper.loop(Looper.java: 213)
at android.app.ActivityThread.main(ActivityThread.java: 4793)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java: 511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java: 789)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java: 556)
at dalvik.system.NativeStart.main(Native Method)

Answer 1

我之前给出的解决方案给我带来了一些问题，因为edittext值在滚动时互换，即当ListView更加自动时，所以这里是最终的解决方案，没有错误，这要归功于link

 //custom adapter as inner class
private class SelectedImagesAdapter extends BaseAdapter{

    private LayoutInflater mInflater;
    int size = 0;

    public SelectedImagesAdapter() {
        mInflater = (LayoutInflater)getActivity()
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        this.size = mPhotosPathList.size();

        int j = 1;
        for (int i = 0; i < size; i++) {

            String defaultCaption = "Photo " + j;
            etStrings.add(defaultCaption);
            j++;
        }


    }//end constructor

    @Override
    public int getCount() {


        return size;
    }

    @Override
    public Object getItem(int position) {
        return position;
    }

    @Override
    public long getItemId(int position) {
        return position;
    }


    @Override
    public View getView(final int position, View convertView, ViewGroup parent) {

        //if we arent given a view inflate one
        //if there's no recycled view passed in inflate one
        final ViewHolder holder;
        if (convertView == null) {

            holder = new ViewHolder();
            convertView = mInflater.inflate(R.layout.list_item_selected_image, null);
            holder.caption = (EditText)
                    convertView.findViewById(R.id.selected_imageCaptionEditText);

            holder.photo = (ImageView)
                    convertView.findViewById(R.id.selected_imageImageView);
            convertView.setTag(holder);

            holder.mWatcher = new EditTextWatcher();
            holder.caption.addTextChangedListener(holder.mWatcher);

        }else {

            holder = (ViewHolder)convertView.getTag();

        }

        holder.mWatcher.setActive(false);
        holder.caption.setText(etStrings.get(position));
        holder.mWatcher.setPosition(position);
        holder.mWatcher.setActive(true);

        Bitmap bitmap = BitmapFactory.decodeFile(mPhotosPathList.get(position));
        //get the screen width  at run time
        int screenWidth = DeviceDimensionsHelper.getDisplayWidth(getActivity());
        //load resized bitmap into an ImageView
        holder.photo.setImageBitmap(BitmapScaler.scaleToFitWidth(bitmap, screenWidth));


        return convertView;//return view object to the list view

    }
}//end private class ImagesAdapter

class ViewHolder {
    EditText caption;
    ImageView photo;
    public EditTextWatcher mWatcher;

}

class EditTextWatcher implements TextWatcher{


    private int mPosition;
    private boolean mActive;

    void setPosition(int position){
        mPosition = position;
    }
    void setActive(boolean active){
        mActive = active;
    }
    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {

    }

    @Override
    public void onTextChanged(CharSequence s, int start, int before, int count) {

    }

    @Override
    public void afterTextChanged(Editable s) {
        if(mActive){
            etStrings.set(mPosition, s.toString());

        }
    }
}