Question

当我使用swipe refreshlayout和json时，我正在获得重复输入我在刷新刷卡刷新后添加了屏幕截图。

当我使用 userArray.clear（）; 以便它完美运行但是listview眨眼了一段时间我认为有更好的帮助的击球手解决方案非常感谢谢谢

看到此链接我想看起来像this没有闪烁列表视图。

MainActivity.java

import android.content.ActivityNotFoundException;
import android.content.Intent;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;

import java.io.File;
import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.os.Environment;
import android.support.v4.widget.SwipeRefreshLayout;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

/**
 * Created by Arpit Patel on 08-Apr-16.
 */

public class MainActivity extends Activity implements SwipeRefreshLayout.OnRefreshListener{
    ListView userList;
    UserCustomAdapter userAdapter=null;
    ArrayList<User> userArray = new ArrayList<User>();
    Button bt_view;
    TextView tv_empty;
    private SwipeRefreshLayout swipeRefreshLayout;
    static List<String> all_pdf;
    // URL to get contacts JSON
    private static String url = "http://api.androidhive.info/songs/albums.php";

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

        swipeRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.swipe_refresh_layout);
        bt_view = (Button) findViewById(R.id.bt_view);
        userList = (ListView) findViewById(R.id.listView);
        tv_empty= (TextView)findViewById(R.id.tv_empty);

        //         set item into adapter
        userAdapter = new UserCustomAdapter(MainActivity.this, R.layout.row_item,
                userArray);
        userList.setAdapter(userAdapter);

        swipeRefreshLayout.setOnRefreshListener(this);
        /**
         * Showing Swipe Refresh animation on activity create
         * As animation won't start on onCreate, post runnable is used
         */
        swipeRefreshLayout.post(new Runnable() {
                                    @Override
                                    public void run() {
                                        swipeRefreshLayout.setRefreshing(true);

                                        Log.d("Runnable method ", "");
                                        new GetPapers().execute();
                                    }
                                }
        );

        /**
         * get on item click listener
         */
        userList.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View v,
                                    final int position, long id) {

                TextView tv_paper_name = (TextView) v.findViewById(R.id.tv_paper_name);
                String PaperName = tv_paper_name.getText().toString();
                File extStore = Environment.getExternalStorageDirectory();
                File myFile = new File(extStore.getAbsolutePath() + "/Exam Papers/" + PaperName + ".pdf");

                if (myFile.exists()) {

                    File pdfFile = new File(Environment.getExternalStorageDirectory() + "/Exam Papers/" + PaperName + ".pdf");  // -> filename
                    Uri path = Uri.fromFile(pdfFile);
                    Intent pdfIntent = new Intent(Intent.ACTION_VIEW);
                    pdfIntent.setDataAndType(path, "application/pdf");
                    pdfIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

                    try {
                        startActivity(pdfIntent);
                    } catch (ActivityNotFoundException e) {
                        Toast.makeText(MainActivity.this, "No Application available to view PDF", Toast.LENGTH_SHORT).show();
                    }
                } else {
                    Toast.makeText(MainActivity.this, "Download file first", Toast.LENGTH_SHORT).show();
                }

            }
        });

        bt_view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                try {
                    String folder_path = Environment.getExternalStorageDirectory().getAbsolutePath() + "/Exam Papers/";
                    all_pdf = new ArrayList<String>();
                    all_pdf = textFiles(folder_path);
                    Log.d("All files ", " " + all_pdf);
                } catch (Exception e) {
                    e.printStackTrace();
                }

                Intent intent = new Intent(MainActivity.this, ActivityTwo.class);
                startActivity(intent);
            }
        });
    }

    /**
     * This method is called when swipe refresh is pulled down
     */
    @Override
    public void onRefresh() {
        Log.d("onRefresh()", "");
        new GetPapers().execute();
    }


    //For fetch the all pdf file in one Directory
    List<String> textFiles(String directory) {
        List<String> textFiles = new ArrayList<String>();
        File dir = new File(directory);
        for (File file : dir.listFiles()) {
            if (file.getName().endsWith((".pdf"))) {
                textFiles.add(file.getName());
            }
        }
        return textFiles;
    }

    /**
     * Async task class to get json by making HTTP call
     * */
    private class GetPapers extends AsyncTask<Void, Void, Void> {

        String Response;

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            // showing refresh animation before making http call
            swipeRefreshLayout.setRefreshing(true);

//            userArray.clear();

        }

        @Override
        protected Void doInBackground(Void... arg0) {
            // Creating service handler class instance
            JSONParser sh = new JSONParser();

            // Making a request to url and getting response
            Response = sh.makeServiceCall(url);

            return null;
        }

        @Override
        protected void onPostExecute(Void result) {
            super.onPostExecute(result);

            if (Response != null) {

                try {
                    JSONArray jsonArray = new JSONArray(Response);

                    for (int i = 0; i < jsonArray.length(); i++){

                        JSONObject jsonObject = jsonArray.getJSONObject(i);

                        String PaperName = jsonObject.getString("name");
                        String Conts = jsonObject.getString("songs_count");
                        String id = jsonObject.getString("id");

                        /**
                         * add item in arraylist
                         */
                        userArray.add(new User(PaperName, Conts, id));

                    }

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

            } else {
                // stopping swipe refresh
                swipeRefreshLayout.setRefreshing(false);
                Log.e("ServiceHandler", "Couldn't get any data from the url");
            }

//            userAdapter.notifyDataSetChanged();
            // stopping swipe refresh
            userAdapter = new UserCustomAdapter(MainActivity.this, R.layout.row_item,
                    userArray);
            userList.setAdapter(userAdapter);
            // stopping swipe refresh
            swipeRefreshLayout.setRefreshing(false);


        }

    }

}

Answer 1

Yoy必须在刷新并调用以下方法之前清除列表

GetPapers（）。执行（）。

喜欢userList.clear();

Answer 2

您必须先清除列表，因为每次刷新时都会添加项目。

您可以使用

执行此操作

yourList.clear();

Answer 3

您应该在再次调用API之前清除列表。

在userArray.clear();方法的GetPapers类中执行循环之前，请按onPostExecute()清除列表。

 @Override
protected void onPostExecute(Void result) {
    super.onPostExecute(result);

    if (Response != null) {
        userArray.clear();  // Here
        try {
            JSONArray jsonArray = new JSONArray(Response);

            for (int i = 0; i < jsonArray.length(); i++){
        }
    }
}....

Answer 4

 @Override
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);

        if (Response != null) {
            userArray.clear(); //Clear Array before populating with values
            try {
                JSONArray jsonArray = new JSONArray(Response);

                for (int i = 0; i < jsonArray.length(); i++){

                    JSONObject jsonObject = jsonArray.getJSONObject(i);

                    String PaperName = jsonObject.getString("name");
                    String Conts = jsonObject.getString("songs_count");
                    String id = jsonObject.getString("id");

                    /**
                     * add item in arraylist
                     */
                    userArray.add(new User(PaperName, Conts, id));

                }

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

        } else {
            // stopping swipe refresh
            swipeRefreshLayout.setRefreshing(false);
            Log.e("ServiceHandler", "Couldn't get any data from the url");
        }




    }

Listview使用SwipeRefreshLayout复制条目

4 个答案: