Question

我通过扩展ArrayAdapter创建自定义ListView。当我第一次正确显示活动时。当我回去重新访问活动时。它在实际数组的末尾重复重复内容。我该如何处理重复内容？

自定义适配器

public class ListAdapter extends ArrayAdapter<Item> {

    public ListAdapter(Context context, int textViewResourceId) {
        super(context, textViewResourceId);
        // TODO Auto-generated constructor stub
    }

    private List<Item> items;

    public ListAdapter(Context context, int resource, List<Item> items) {
        super(context, resource, items);
        this.items = items;

    }

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

        if (v == null) {
            LayoutInflater vi;
            vi = LayoutInflater.from(getContext());
            v = vi.inflate(R.layout.list_item_default, null);
        }

        Item p = items.get(position);

        if (p != null) {

            TextView list_title = (TextView) v.findViewById(R.id.list_title);
            TextView list_description = (TextView) v
                    .findViewById(R.id.list_description);
            TextView list_timestamp = (TextView) v
                    .findViewById(R.id.list_timestamp);
            ImageView list_image = (ImageView) v.findViewById(R.id.list_image);

            if (list_title != null) {
                list_title.setText(p.getItemTitle());
            }

            if (list_description != null) {
                list_description.setText(p.getItemDescription());
            }

            if (list_timestamp != null) {
                list_timestamp.setText(p.getItemTimestamp());
            }

            if (list_image != null) {
                Log.d("bMobile", "inside getView() image");
                try {
                    URL imageURL = new URL(p.getItemImage());
                    HttpURLConnection con = (HttpURLConnection) imageURL
                            .openConnection();
                    InputStream inputStrem = con.getInputStream();
                    Bitmap image = BitmapFactory.decodeStream(inputStrem);
                    if (null != image)
                        list_image.setImageBitmap(image);
                    else
                        Log.d("bMobile", "Bitmap is Null");
                } catch (Exception e) {
                }
            }
        }

        return v;
    }

}

活动

public class MessagesActivity extends Activity {

    ListView listview;
    static ArrayList<Item> dataArray = new ArrayList<Item>();
    static ArrayList<Item> contentArray = new ArrayList<Item>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_messages);

        setupViews();
        try {
            contentArray = generateArray(createJson());
        } catch (JSONException e) {
            e.printStackTrace();
        }

        listview.setAdapter(new ListAdapter(MessagesActivity.this,
                R.layout.list_item_default, contentArray));
    }

    public void setupViews() {

        listview = (ListView) findViewById(R.id.list_items);

        ((TextView) findViewById(R.id.title_text))
                .setText(R.string.description_messages);
    }

    // It creates a JSON and returns JSON string
    public String createJson() throws JSONException {
        JSONArray itemArray = new JSONArray();

        JSONObject itemObject1 = new JSONObject();
        itemObject1.put("title", "Harsha MV");
        itemObject1.put("timestamp", "2 hours");
        itemObject1.put("description", "Bangalore, India");
        itemObject1.put("display_photo", "http://i.imgur.com/enUZr.jpg");

        JSONObject itemObject2 = new JSONObject();
        itemObject2.put("title", "Avinash G");
        itemObject2.put("timestamp", "4 days");
        itemObject2.put("description", "Mysore, India");
        itemObject2.put("display_photo", "http://noblevelop.com/wp-content/uploads/2011/06/profile.jpg");

        JSONObject itemObject3 = new JSONObject();
        itemObject3.put("title", "Jyosna Sahoo");
        itemObject3.put("timestamp", "1  year");
        itemObject3.put("description", "Rourkela, India");
        itemObject3.put("display_photo", "http://noblevelop.com/wp-content/uploads/2011/06/profile.jpg");

        itemArray.put(itemObject1);
        itemArray.put(itemObject2);
        itemArray.put(itemObject3);

        return itemArray.toString();
    }

    public ArrayList<Item> generateArray(String JSONdata) throws JSONException {

        JSONArray listData = new JSONArray(JSONdata);
        for (int i = 0; i < listData.length(); i++) {

            JSONObject listObject = listData.getJSONObject(i);
            String item_title = listObject.getString("title");
            String item_description = listObject.getString("description");
            String item_timestamp = listObject.getString("timestamp");
            String item_image = listObject.getString("display_photo");

            Item ObjectItem = new Item(item_title, item_timestamp,
                    item_description, item_image);
            dataArray.add(ObjectItem);

        }
        return dataArray;
    }

}

Answer 1

dataArray将在每个onCreate（每次显示视图时调用）上增长，因为您要添加新项目。

只需在onCreate开头就明确dataArray就可以解决问题。

Answer 2

以这种方式修改generateArray()

public ArrayList<Item> generateArray(String JSONdata) throws JSONException {
        ArrayList<Item> dataArray = new ArrayList<Item>();

        //rest of your code..
        return dataArray;
}

Answer 3

更改你的getView方法，它会工作..我发布代码......

  public View getView(int position, View convertView, ViewGroup parent) { 
     convertView=null;
     View v;
     LayoutInflater vi; 
     vi = LayoutInflater.from(getContext()); 
     v = vi.inflate(R.layout.list_item_default, null); 


    Item p = items.get(position); 

    if (p != null) { 

        TextView list_title = (TextView) v.findViewById(R.id.list_title); 
        TextView list_description = (TextView) v 
                .findViewById(R.id.list_description); 
        TextView list_timestamp = (TextView) v 
                .findViewById(R.id.list_timestamp); 
        ImageView list_image = (ImageView) v.findViewById(R.id.list_image); 

        if (list_title != null) { 
            list_title.setText(p.getItemTitle()); 
        } 

        if (list_description != null) { 
            list_description.setText(p.getItemDescription()); 
        } 

        if (list_timestamp != null) { 
            list_timestamp.setText(p.getItemTimestamp()); 
        } 

        if (list_image != null) { 
            Log.d("bMobile", "inside getView() image"); 
            try { 
                URL imageURL = new URL(p.getItemImage()); 
                HttpURLConnection con = (HttpURLConnection) imageURL 
                        .openConnection(); 
                InputStream inputStrem = con.getInputStream(); 
                Bitmap image = BitmapFactory.decodeStream(inputStrem); 
                if (null != image) 
                    list_image.setImageBitmap(image); 
                else 
                    Log.d("bMobile", "Bitmap is Null"); 
            } catch (Exception e) { 
            } 
        } 
    } 

    return v; 
}

自定义列表查看重复项目

3 个答案: