Question

我正在尝试使用url中的json填充listview。 Json从php页面通过Mysql数据库刷新。当我添加新行或删除行时，我想刷新列表。现在，要查看更改，我应用此步骤 - ＆gt; 设置 - ＆gt;应用程序 - ＆gt; MyApp-＆gt;清除缓存 我试过listAdapter.notifyDataSetChanged（）;但不起作用。我试着用意图调用MainActivity，但这也不行。我无法实现pull刷新抱歉语言不好亲切的问候这是我的代码 - ＆gt;

public class MainActivity extends Activity {
    private static final String TAG = MainActivity.class.getSimpleName();
    private ListView listView;
    private FeedListAdapter listAdapter;
    private List<FeedItem> feedItems;
    private String URL_FEED = "http://mehmetcantas.info/images/";
    public Button refreshs;

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

        listView = (ListView) findViewById(R.id.list);

        refreshs = (Button) findViewById(R.id.refresh);

        feedItems = new ArrayList<FeedItem>();

        listAdapter = new FeedListAdapter(this, feedItems);
        listView.setAdapter(listAdapter);

        // These two lines not needed,
        // just to get the look of facebook (changing background color & hiding the icon)
        getActionBar().setBackgroundDrawable(new ColorDrawable(Color.parseColor("#3b5998")));
        getActionBar().setIcon(
                   new ColorDrawable(getResources().getColor(android.R.color.transparent)));

        // We first check for cached request
        Cache cache = AppController.getInstance().getRequestQueue().getCache();
        Entry entry = cache.get(URL_FEED);
        if (entry != null) {
            // fetch the data from cache
            try {
                String data = new String(entry.data, "UTF-8");
                try {
                    parseJsonFeed(new JSONObject(data));
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }

        } else {
            // making fresh volley request and getting json
            JsonObjectRequest jsonReq = new JsonObjectRequest(Method.GET,
                    URL_FEED, null, new Response.Listener<JSONObject>() {

                        @Override
                        public void onResponse(JSONObject response) {
                            VolleyLog.d(TAG, "Response: " + response.toString());

                            if (response != null) {
                                parseJsonFeed(response);
                            }
                        }
                    }, new Response.ErrorListener() {

                        @Override
                        public void onErrorResponse(VolleyError error) {
                            VolleyLog.d(TAG, "Error: " + error.getMessage());
                        }
                    });

            // Adding request to volley request queue
            AppController.getInstance().addToRequestQueue(jsonReq);
        }

    }



    /**
     * Parsing json reponse and passing the data to feed view list adapter
     * */
    private void parseJsonFeed(JSONObject response) {
        try {
            JSONArray feedArray = response.getJSONArray("feed");

            for (int i = 0; i < feedArray.length(); i++) {
                JSONObject feedObj = (JSONObject) feedArray.get(i);

                FeedItem item = new FeedItem();
                item.setId(feedObj.getInt("id"));
                item.setName(feedObj.getString("name"));

                // Image might be null sometimes
                String image = feedObj.isNull("image") ? null : feedObj
                        .getString("image");
                item.setImge(image);
                item.setStatus(feedObj.getString("status"));
                item.setProfilePic(feedObj.getString("profilePic"));
                item.setTimeStamp(feedObj.getString("timeStamp"));

                // url might be null sometimes
                String feedUrl = feedObj.isNull("url") ? null : feedObj
                        .getString("url");
                item.setUrl(feedUrl);

                feedItems.add(item);
            }

            // notify data changes to list adapater
            listAdapter.notifyDataSetChanged();
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
//  public void onClick(View view) {
//      switch (view.getId()) {
//  
//
//      case R.id.refresh:
//          
//             Intent intent = getIntent();
//              finish();
//              startActivity(intent);
//  
//          break;
//      }
//
//  }
//  

}

Answer 1

我认为每次进行更改时都应该再次设置适配器

所以在删除或添加或任何更改后，请调用此方法：

listView.setAdapter(listAdapter);

Answer 2

我解决了问题但没有效率问题。如果有人需要，我会分享。

我取消了一个reflesh按钮并使用onDestroy

调用intent current活动

public void onClick(View view) {
        switch (view.getId()) {
        case R.id.refresh:
            Intent intent = getIntent();
            onDestroy();
            finish();
            startActivity(intent);

            break;
        }

    }

像我这样的onDestroy方法

@Override
protected void onDestroy() {
    super.onDestroy();

    try {
        trimCache(this);
       // Toast.makeText(this,"onDestroy " ,Toast.LENGTH_LONG).show();
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

}
public static void trimCache(Context context) {
    try {
       File dir = context.getCacheDir();
       if (dir != null && dir.isDirectory()) {
          deleteDir(dir);
       }
    } catch (Exception e) {
       // TODO: handle exception
    }
 }

 public static boolean deleteDir(File dir) {
    if (dir != null && dir.isDirectory()) {
       String[] children = dir.list();
       for (int i = 0; i < children.length; i++) {
          boolean success = deleteDir(new File(dir, children[i]));
          if (!success) {
             return false;
          }
       }
    }

    // The directory is now empty so delete it
    return dir.delete();
 }

如何刷新Android中的MainActivity或Listview

2 个答案: