如何实现滑动以刷新从其他活动调用的JSON提要的片段

Question

我想添加滑动以刷新，我无法找到如何从ScrollableTabActivity.java调用刷新

OneFragment.java

public class OneFragment extends Fragment implements SwipeRefreshLayout.OnRefreshListener {

    private ListView listView;
    private FeedListAdapter listAdapter;
    private SwipeRefreshLayout swipeRefreshLayout;
    private FeedListAdapter adapter;
    private int id = 0;

    public OneFragment() {
        // Required empty public constructor
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view = inflater.inflate(R.layout.fragment_one, container, false);
        listView = (ListView) view.findViewById(R.id.list);
        listAdapter = new FeedListAdapter(getActivity(), ScrollableTabsActivity.feedItems);
        swipeRefreshLayout = (SwipeRefreshLayout) view.findViewById(R.id.swipe_refresh_layout);
        listView.setAdapter(listAdapter);
        swipeRefreshLayout.setOnRefreshListener(this);
        return view;

    }

ScrollableTabsActivity.java

public class ScrollableTabsActivity extends AppCompatActivity {

    private static final String TAG = ScrollableTabsActivity.class.getSimpleName();

    private Toolbar toolbar;
    private TabLayout tabLayout;
    private ViewPager viewPager;
    public static List<FeedItem> feedItems =new ArrayList<>();
    public static List<FeedItem> feedItems1 =new ArrayList<>();
    public static List<FeedItem> feedItems2 =new ArrayList<>();
    public static List<FeedItem> feedItems3 =new ArrayList<>();
    public static List<FeedItem> feedItems4 =new ArrayList<>();
    private String URL_FEED = "http://www.goalert.in/feed/engineering.json";
    private String URL_FEED1 = "http://www.goalert.in/feed/medical.json";
    private String URL_FEED2 = "http://www.goalert.in/feed/bschool.json";
    private String URL_FEED3 = "http://www.goalert.in/feed/law.json";
    private String URL_FEED4 ="http://www.goalert.in/feed/GovernmentExams.json";

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

        toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);

        viewPager = (ViewPager) findViewById(R.id.viewpager);
        setupViewPager(viewPager);

        tabLayout = (TabLayout) findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(viewPager);

        Cache cache = AppController.getInstance().getRequestQueue().getCache();
        Cache.Entry entry = cache.get(URL_FEED);
        Cache cache1 = AppController.getInstance().getRequestQueue().getCache();
        Cache.Entry entry1 = cache1.get(URL_FEED1);
        Cache cache2 = AppController.getInstance().getRequestQueue().getCache();
        Cache.Entry entry2 = cache2.get(URL_FEED2);
        Cache cache3 = AppController.getInstance().getRequestQueue().getCache();
        Cache.Entry entry3 = cache3.get(URL_FEED3);
        Cache cache4 = AppController.getInstance().getRequestQueue().getCache();
        Cache.Entry entry4 = cache4.get(URL_FEED4);

        //if  and else for Engineering Feeds
        feedItems.clear();
        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(Request.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);
        }


        //if and else for Medical feeds

        feedItems1.clear();

        if (entry1 != null) {
            // fetch the data from cache
            try {
                String data = new String(entry1.data, "UTF-8");
                try {
                    parseJsonFeed1(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(Request.Method.GET,
                    URL_FEED1, null, new Response.Listener<JSONObject>() {

                @Override
                public void onResponse(JSONObject response) {
                    VolleyLog.d(TAG, "Response: " + response.toString());
                    if (response != null) {
                        parseJsonFeed1(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);
        }

        //if and else for bschool feeds
        feedItems2.clear();
        if (entry2 != null) {
            // fetch the data from cache
            try {
                String data = new String(entry2.data, "UTF-8");
                try {
                    parseJsonFeed2(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(Request.Method.GET,
                    URL_FEED2, null, new Response.Listener<JSONObject>() {

                @Override
                public void onResponse(JSONObject response) {
                    VolleyLog.d(TAG, "Response: " + response.toString());
                    if (response != null) {
                        parseJsonFeed2(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);
        }
        feedItems3.clear();
        //if and else for law feeds
        if (entry3 != null) {
            // fetch the data from cache
            try {
                String data = new String(entry3.data, "UTF-8");
                try {
                    parseJsonFeed3(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(Request.Method.GET,
                    URL_FEED3, null, new Response.Listener<JSONObject>() {

                @Override
                public void onResponse(JSONObject response) {
                    VolleyLog.d(TAG, "Response: " + response.toString());
                    if (response != null) {
                        parseJsonFeed3(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);
        }
        feedItems4.clear();
        //if and else for Government Exams feeds
        if (entry4 != null) {
            // fetch the data from cache
            try {
                String data = new String(entry4.data, "UTF-8");
                try {
                    parseJsonFeed4(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(Request.Method.GET,
                    URL_FEED4, null, new Response.Listener<JSONObject>() {

                @Override
                public void onResponse(JSONObject response) {
                    VolleyLog.d(TAG, "Response: " + response.toString());
                    if (response != null) {
                        parseJsonFeed4(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);
        }

    }


    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

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


    private void parseJsonFeed1(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);

                feedItems1.add(item);
            }

            // notify data changes to list adapater

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

    private void parseJsonFeed2(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);

                feedItems2.add(item);
            }

            // notify data changes to list adapater

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

    private void parseJsonFeed3(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);

                feedItems3.add(item);
            }

            // notify data changes to list adapater

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

    private void parseJsonFeed4(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);

                feedItems4.add(item);
            }

            // notify data changes to list adapater

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




    private void setupViewPager(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
        adapter.addFrag(new OneFragment(), "Engineering");
        adapter.addFrag(new TwoFragment(), "Medical");
        adapter.addFrag(new ThreeFragment(), "B-School");
        adapter.addFrag(new FourFragment(), "Law");
        adapter.addFrag(new FiveFragment(), "Government Services");
        viewPager.setAdapter(adapter);
    }

    class ViewPagerAdapter extends FragmentPagerAdapter {
        private final List<Fragment> mFragmentList = new ArrayList<>();
        private final List<String> mFragmentTitleList = new ArrayList<>();

        public ViewPagerAdapter(FragmentManager manager) {
            super(manager);
        }

        @Override
        public Fragment getItem(int position) {
            return mFragmentList.get(position);
        }
        @Override
        public int getCount() {
            return mFragmentList.size();
        }

        public void addFrag(Fragment fragment, String title) {
            mFragmentList.add(fragment);
            mFragmentTitleList.add(title);
        }

        @Override
        public CharSequence getPageTitle(int position) {
            return mFragmentTitleList.get(position);
        }
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_logout, menu);
        return true;
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();
        //noinspection SimplifiableIfStatement
        if (id == R.id.profile_done) {
            SharedPreferences preferences = getSharedPreferences("AndroidHiveLogin", 0);
            preferences.edit().remove("isLoggedIn").commit();
            startActivity(new Intent(ScrollableTabsActivity.this, LoginActivity.class));
            finish();
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

Answer 1

由于您的片段实现了SwipeRefreshLayout.OnRefreshListener ，因此您只需调用onRefresh() 。 如果您打算手动强制刷新。

例：

((SwipeRefreshLayout.OnRefreshListener) pagerAdapter.getItem(position)).onRefresh();