列表中的ImageView不会清除以前的图像

时间：2015-02-23 04:53:37

标签： android listview imageview

我ListView接受ArrayAdapter。当共享图像时，ArrayAdapter有一个由{Picasso（来自Square的图书馆）填充的ImageView。但是，在共享带有图像的消息并将其放置在该列表项的ImageView中之后，如果共享了另一条没有图像的消息，则会将相同的先前图像填充到ImageView中，而不是是空白的，因为它应该是没有共享图像。

我已经研究并尝试将ImageView设置为null或透明，如果没有共享图像但没有任何效果。到目前为止，我尝试过：

sharedSpecial.setImageBitmap(null);和sharedSpecial.setImageResource(0);但不起作用。

我怎样才能清除＆＃34;如果没有共享当前图像，ImageView会显示ListView中的上一张图片吗？

用于设置共享类型的图像的ArrayAdapter类如下：

public class DiscussArrayAdapter extends ArrayAdapter<OneComment> {

private TextView countryName;
private ImageView sharedSpecial;

private MapView locationMap;
private GoogleMap map;

private List<OneComment> countries = new ArrayList<OneComment>();
private LinearLayout wrapper;


String getSharedSpecialURL = null;
String getSharedSpecialWithLocationURL = null;

String specialsActionURL = "http://" + Global.getIpAddress()
        + ":3000/getSharedSpecial/";

String specialsLocationActionURL = "http://" + Global.getIpAddress()
        + ":3000/getSharedSpecialWithLocation/";

String JSON = ".json";

@Override
public void add(OneComment object) {
    countries.add(object);
    super.add(object);
}

public DiscussArrayAdapter(Context context, int textViewResourceId) {
    super(context, textViewResourceId);
}

public int getCount() {
    return this.countries.size();
}

public OneComment getItem(int index) {
    return this.countries.get(index);
}

public View getView(int position, View convertView, ViewGroup parent) {
    View row = convertView;
    if (row == null) {
        LayoutInflater inflater = (LayoutInflater) this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        row = inflater.inflate(R.layout.message_list_item, parent, false);
    }

    wrapper = (LinearLayout) row.findViewById(R.id.wrapper);

    OneComment comment = getItem(position);

    countryName = (TextView) row.findViewById(R.id.comment);

    sharedSpecial = (ImageView) row.findViewById(R.id.sharedSpecial);

    countryName.setText(comment.comment);

    // Initiating Volley
    final RequestQueue requestQueue = VolleySingleton.getsInstance().getRequestQueue();

    // Check if message has campaign or campaign/location attached
    if (comment.campaign_id == "0" && comment.location_id == "0") {

        sharedSpecial.setImageBitmap(null);

    } else if (comment.campaign_id != "0" && comment.location_id != "0") {

        // If both were shared
        getSharedSpecialWithLocationURL = specialsLocationActionURL + comment.campaign_id + "/" + comment.location_id + JSON;


        // GET JSON data and parse
        JsonObjectRequest getCampaignLocationData = new JsonObjectRequest(Request.Method.GET, getSharedSpecialWithLocationURL, null,
                new Response.Listener<JSONObject>() {
                    @Override
                    public void onResponse(JSONObject response) {

                        // Parse the JSON:
                        try {
                            resultObject = response.getJSONObject("shared");

                            imageObject = resultObject.getJSONObject("image");
                            adImageURL = imageObject.getString("url");


                        } catch (JSONException e) {
                            e.printStackTrace();
                        }

                        // Get and set image
                        Picasso.with(getContext()).load("http://" + Global.getIpAddress() + ":3000" + adImageURL).into(sharedSpecial);
                        sharedSpecial.setImageResource(0);

                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        Log.d("Error.Response", error.toString());
                    }
                }
        );

        requestQueue.add(getCampaignLocationData);


    } else if (comment.campaign_id != "0" && comment.location_id == "0") {

        // Just the campaign is shared
        getSharedSpecialURL = specialsActionURL + comment.campaign_id + JSON;

        // Test Campaign id = 41

        // GET JSON data and parse

        JsonObjectRequest getCampaignData = new JsonObjectRequest(Request.Method.GET, getSharedSpecialURL, null,
                new Response.Listener<JSONObject>() {
                    @Override
                    public void onResponse(JSONObject response) {

                        // Parse the JSON:
                        try {
                            resultObject = response.getJSONObject("shared");

                            imageObject = resultObject.getJSONObject("image");
                            adImageURL = imageObject.getString("url");

                        } catch (JSONException e) {
                            e.printStackTrace();
                        }

                        // Get and set image
                        Picasso.with(getContext()).load("http://" + Global.getIpAddress() + ":3000" + adImageURL).into(sharedSpecial);
                        sharedSpecial.setImageResource(0);

                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        Log.d("Error.Response", error.toString());
                    }
                }
        );

        requestQueue.add(getCampaignData);

        // Location set to empty
    }

    // If left is true, then yello, if not then set to green bubble
    countryName.setBackgroundResource(comment.left ? R.drawable.bubble_yellow : R.drawable.bubble_green);
    wrapper.setGravity(comment.left ? Gravity.LEFT : Gravity.RIGHT);

    return row;
}

}

1 个答案:

答案 0 :(得分：0)

您的getView方法存在问题。您没有将膨胀的xml附加到行。您正在全局声明组件（textview等），而最好创建一个可以附加的持有者类。

请为您的适配器尝试以下操作：

<强>更新 添加了构造函数，将列表作为参数。现在你像这样调用适配器：

DiscussArrayAdapter adapter = new DiscussArrayAdapter(context, R.layout.message_list_item, countries);

listView.setAdapter(adapter);

然后重要的是要信任适配器 notifyDataSetChanged 。

在活动中全局创建国家/地区列表和适配器，每当您从列表中添加/删除项目时，只需调用adapter.notifyDataSetChanged（）;

<强>适配器： 

public class DiscussArrayAdapter extends ArrayAdapter<OneComment>{


private MapView locationMap;
private GoogleMap map;

private List<OneComment> countries;

public DiscussArrayAdapter(Context context, int resource, List<OneComment> objects) {
    super(context, resource, objects);

    this.countries = objects;
}
String getSharedSpecialURL = null;
String getSharedSpecialWithLocationURL = null;

String specialsActionURL = "http://" + Global.getIpAddress()
        + ":3000/getSharedSpecial/";

String specialsLocationActionURL = "http://" + Global.getIpAddress()
        + ":3000/getSharedSpecialWithLocation/";

String JSON = ".json";

@Override
public void add(OneComment object) {
    countries.add(object);
    super.add(object);
}

public DiscussArrayAdapter(Context context, int textViewResourceId) {
    super(context, textViewResourceId);
}

public int getCount() {
    return this.countries.size();
}

public OneComment getItem(int index) {
    return this.countries.get(index);
}

public View getView(int position, View row, ViewGroup parent) {

     //Create instance of inflated view holder
    Holder holder;

    if (row == null) {

        //Its the first time we are going to inflate the view, get new instance of Holder            
        holder = new Holder();

        //Inflate view
        LayoutInflater inflater = (LayoutInflater) this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        row = inflater.inflate(R.layout.message_list_item, parent, false);

        //Put components in the holder
        holder.countryName = (TextView) row.findViewById(R.id.comment);
        holder.sharedSpecial = (ImageView) row.findViewById(R.id.sharedSpecial);
        holder.wrapper = (LinearLayout) row.findViewById(R.id.wrapper);

        //Attach holder to the row
        row.setTag(holder);

    }else{

        //Row was inflated before get holder 
        holder = (Holder)row.getTag();
    }



    OneComment comment = getItem(position);
    countryName.setText(comment.comment);

    // Initiating Volley
    final RequestQueue requestQueue = VolleySingleton.getsInstance().getRequestQueue();

    // Check if message has campaign or campaign/location attached
    if (comment.campaign_id.equals("0") && comment.location_id.equals("0")) {

        sharedSpecial.setImageBitmap(null);

    } else if (!comment.campaign_id.equals("0") && !comment.location_id.equals("0")) {

        // If both were shared
        getSharedSpecialWithLocationURL = specialsLocationActionURL + comment.campaign_id + "/" + comment.location_id + JSON;


        // GET JSON data and parse
        JsonObjectRequest getCampaignLocationData = new JsonObjectRequest(Request.Method.GET, getSharedSpecialWithLocationURL, null,
                new Response.Listener<JSONObject>() {
                    @Override
                    public void onResponse(JSONObject response) {

                        // Parse the JSON:
                        try {
                            resultObject = response.getJSONObject("shared");

                            imageObject = resultObject.getJSONObject("image");
                            adImageURL = imageObject.getString("url");


                        } catch (JSONException e) {
                            e.printStackTrace();
                        }

                        // Get and set image
                        Picasso.with(getContext()).load("http://" + Global.getIpAddress() + ":3000" + adImageURL).into(sharedSpecial);
                        sharedSpecial.setImageResource(0);

                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        Log.d("Error.Response", error.toString());
                    }
                }
        );

        requestQueue.add(getCampaignLocationData);


    } else if (!comment.campaign_id.equals("0") && comment.location_id.equals("0")) {

        // Just the campaign is shared
        getSharedSpecialURL = specialsActionURL + comment.campaign_id + JSON;

        // Test Campaign id = 41

        // GET JSON data and parse

        JsonObjectRequest getCampaignData = new JsonObjectRequest(Request.Method.GET, getSharedSpecialURL, null,
                new Response.Listener<JSONObject>() {
                    @Override
                    public void onResponse(JSONObject response) {

                        // Parse the JSON:
                        try {
                            resultObject = response.getJSONObject("shared");

                            imageObject = resultObject.getJSONObject("image");
                            adImageURL = imageObject.getString("url");

                        } catch (JSONException e) {
                            e.printStackTrace();
                        }

                        // Get and set image
                        Picasso.with(getContext()).load("http://" + Global.getIpAddress() + ":3000" + adImageURL).into(sharedSpecial);
                        sharedSpecial.setImageResource(0);

                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        Log.d("Error.Response", error.toString());
                    }
                }
        );

        requestQueue.add(getCampaignData);

        // Location set to empty
    }

    // If left is true, then yello, if not then set to green bubble
    countryName.setBackgroundResource(comment.left ? R.drawable.bubble_yellow : R.drawable.bubble_green);
    wrapper.setGravity(comment.left ? Gravity.LEFT : Gravity.RIGHT);

    return row;
}

private class Holder{
    TextView countryName;
    ImageView sharedSpecial;
    LinearLayout wrapper;
}

}
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