Question

当我尝试在我的Android应用程序上的片段上实现gridview时，出现 getApplicationContext（）错误和 getSystemService 错误。我该如何解决这个问题？我的源代码有什么错误吗？

`

private GridView photoGrid;
private int mPhotoSize, mPhotoSpacing;
private ImageAdapter imageAdapter;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment1, container, false);


    // get the photo size and spacing
    mPhotoSize = getResources().getDimensionPixelSize(R.dimen.photo_size);
    mPhotoSpacing = getResources().getDimensionPixelSize(R.dimen.photo_spacing);

    // initialize image adapter
    imageAdapter = new ImageAdapter();

    photoGrid = (GridView) getView().findViewById(R.id.albumGrid);
    photoGrid.setOnItemClickListener(this);

    GridView gridview = (GridView) getView().findViewById (R.id.albumGrid);
        gridview.setAdapter (new ImageAdapter()); 

        gridview.setOnItemClickListener(new OnItemClickListener()
        {
            public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
                // TODO Auto-generated method stub

                Intent myIntent = null;
                if(position == 0){
                    myIntent = new Intent(v.getContext(), PregnancyStagesMainActivity.class);
                }
                if(position == 1){
                    myIntent = new Intent(v.getContext(), ComplicationsMainActivity.class);
                }
                if(position == 2){
                    myIntent = new Intent(v.getContext(), DietAndFitnessMainActivity.class);
                }
                if(position == 3){
                    myIntent = new Intent(v.getContext(), MythsAndFactsMainActivity.class);
                }
                if(position == 4){
                    myIntent = new Intent(v.getContext(), HelplinesMainActivity.class);
                }
                if(position == 5){
                    myIntent = new Intent(v.getContext(), FaqsMainActivity.class);
                }
                startActivity(myIntent);
            }
        });


    // set image adapter to the GridView
    photoGrid.setAdapter(imageAdapter);

    // Set the Required Animation to GridView and start the Animation
    // use fly_in_from_center to have 2nd type of animation effect (snapshot 2)
    Animation anim = AnimationUtils.loadAnimation(getApplicationContext(), R.anim.in_from_left);
    gridview.setAnimation(anim);
    anim.start();

    // get the view tree observer of the grid and set the height and numcols dynamically
    photoGrid.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
            if (imageAdapter.getNumColumns() == 0) {
                final int numColumns = (int) Math.floor(photoGrid.getWidth() / (mPhotoSize + mPhotoSpacing));
                if (numColumns > 0) {
                    final int columnWidth = (photoGrid.getWidth() / numColumns) - mPhotoSpacing;
                    imageAdapter.setNumColumns(numColumns);
                    imageAdapter.setItemHeight(columnWidth);

                }
            }
        }
    });
}

// ///////// ImageAdapter class /////////////////
public class ImageAdapter extends BaseAdapter {
    private LayoutInflater mInflater;
    private int mItemHeight = 0;
    private int mNumColumns = 0;
    private RelativeLayout.LayoutParams mImageViewLayoutParams;

    public ImageAdapter() {
        mInflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        mImageViewLayoutParams = new RelativeLayout.LayoutParams(LayoutParams.MATCH_PARENT,
                LayoutParams.MATCH_PARENT);
    }

    public int getCount() {
        return CONTENT.length;
    }

    // set numcols
    public void setNumColumns(int numColumns) {
        mNumColumns = numColumns;
    }

    public int getNumColumns() {
        return mNumColumns;
    }

    // set photo item height
    public void setItemHeight(int height) {
        if (height == mItemHeight) {
            return;
        }
        mItemHeight = height;
        mImageViewLayoutParams = new RelativeLayout.LayoutParams(LayoutParams.MATCH_PARENT, mItemHeight);
        notifyDataSetChanged();
    }

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

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

    public View getView(final int position, View view, ViewGroup parent) {

        if (view == null)
            view = mInflater.inflate(R.layout.photo_item, null);

        ImageView cover = (ImageView) view.findViewById(R.id.cover);
        TextView title = (TextView) view.findViewById(R.id.title);

        cover.setLayoutParams(mImageViewLayoutParams);

        // Check the height matches our calculated column width
        if (cover.getLayoutParams().height != mItemHeight) {
            cover.setLayoutParams(mImageViewLayoutParams);
        }

        cover.setImageResource(ICONS[position % ICONS.length]);
        title.setText(CONTENT[position % CONTENT.length]);

        return view;
    }
}

@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
    // TODO Auto-generated method stub

}


}    `

Answer 1

Fragment不是Context，因此Fragment

中没有这些调用可用

使用getActivity()对这些调用进行前缀，以获取主机Activity（这是一个上下文），因此将它们更改为：

getActivity().getSystemService()

和

getActivity().getApplicationContext()

在片段上实现gridview的错误

1 个答案: