如何在Android中刷新MainActivity或Listview
如何在Android中刷新MainActivity或Listview
提问于 2014-07-20 19:24:21
我正在尝试用url中的json填充listview。通过Mysql数据库从php页面刷新Json。添加新行或删除行时，希望刷新列表。现在，为了查看更改，我应用了以下步骤-- Settings->Application->MyApp->Clean缓存--我尝试了listAdapter.notifyDataSetChanged()；但是不起作用。我尝试过有意图地调用MainActivity，但这也不起作用。我不能实现拉刷新--抱歉，糟糕的语言类型--这里是我的代码->
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;
// }
//
// }
//
}回答 2
Stack Overflow用户
回答已采纳
发布于 2014-07-20 21:16:09
我解决了这个问题，但效率不高。如果有人需要的话，我会分享的。
我是一个自反式按钮，并调用意图当前活动与onDestroy
public void onClick(View view) {
switch (view.getId()) {
case R.id.refresh:
Intent intent = getIntent();
onDestroy();
finish();
startActivity(intent);
break;
}
}我的onDestroy方法如下
@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();
}Stack Overflow用户
发布于 2014-07-20 21:08:04
我认为您应该在每次更改时重新设置适配器。
因此，在删除、添加或任何更改之后，只需调用以下命令：
listView.setAdapter(listAdapter);页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/24854061
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