内容未在viewpager中更改选项卡时更新 - Tablayout

Question

我将动态id从arraylist存储到动态创建的每个选项卡

我使用了ViewPagerOnTabSelectedListener，它获取了单击的选项卡的id并将其存储在共享首选项中。

我正在将共享偏好中的id用于片段，根据该ID获取每个标签中的自定义列表。

是的，问题是自定义列表没有在选项卡点击时刷新，但是它已经获取旧值，它没有根据共享偏好中的id进行更新

public class ScrollableTabsActivity extends AppCompatActivity {

    private Toolbar toolbar;
    private TabLayout tabLayout;
    private ViewPager viewPager;
    ConnectionClass connectionClass;
    ArrayList<String> al,idal,pidal;


    @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);
        getSupportActionBar().setDisplayShowTitleEnabled(false);


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


        connectionClass = new ConnectionClass();


        al = new ArrayList<String>();
        idal = new ArrayList<String>();
        pidal = new ArrayList<String>();


        ScrollableTabsActivity.DoLogin doLogin = new ScrollableTabsActivity.DoLogin();
        doLogin.execute("");


    }

    private void setupTags() {
        int i;



        for(i=0;i<al.size();i++) {
          /*  Tag t= new Tag();
            t.setId(idal.get(i));
            tabLayout.getTabAt(i).setTag(t);
*/

            tabLayout.getTabAt(i).setTag(idal.get(i));

        }

        tabLayout.setOnTabSelectedListener(new TabLayout.ViewPagerOnTabSelectedListener(viewPager){
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                super.onTabSelected(tab);

             //   CharSequence numTab = ((Tag)tab.getTag()).getId();
                CharSequence numTab = tab.getTag().toString();

                SharedPreferences preferences2 = getSharedPreferences("AUTHENTICATION_FILE_NAME2", Context.MODE_WORLD_WRITEABLE);
                SharedPreferences.Editor editor2 = preferences2.edit();

                editor2.putString("tabselected",numTab.toString());
                editor2.putString("Authentication_Status", "true");
                editor2.apply();



            }

        });
    }
    private void setupViewPager(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
        int i;
        for(i=0;i<al.size();i++){

        adapter.addFrag(new MainActivity(), al.get(i),idal.get(i));

        }
        viewPager.setAdapter(adapter);


    }

    class ViewPagerAdapter extends FragmentPagerAdapter {
        private final List<Fragment> mFragmentList = new ArrayList<>();
        private final List<String> mFragmentTitleList = new ArrayList<>();
        private final List<String> mFragmentId = 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,String id) {
            mFragmentList.add(fragment);
            mFragmentTitleList.add(title);
            mFragmentId.add(id);

        }

        @Override
        public CharSequence getPageTitle(int position) {
            return mFragmentTitleList.get(position);
        }

        public int getItemPosition(Object object) {
            return POSITION_NONE;
        }

    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Take appropriate action for each action item click
        switch (item.getItemId()) {
            case R.id.action_cart:
                cart();
                return true;

            default:
                return super.onOptionsItemSelected(item);
        }
    }

    /**
     * Launching new activity
     * */
    private void cart() {
        Intent i = new Intent(ScrollableTabsActivity.this, Cart.class);
        startActivity(i);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }


    @Override
    public void onBackPressed() {
        super.onBackPressed();
        Vibrator v = (Vibrator) getApplicationContext().getSystemService(Context.VIBRATOR_SERVICE);
        v.vibrate(500);
        MainActivity m= new MainActivity();
        m.vacatelist();

    }

    public class DoLogin extends AsyncTask<String,String,String>
    {
        String z = "";
        Boolean isSuccess = false;


        @Override
        protected void onPreExecute() {

        }

        @Override
        protected void onPostExecute(String r) {

            if(isSuccess) {
                SharedPreferences preferences2 = getSharedPreferences("AUTHENTICATION_FILE_NAME2", Context.MODE_WORLD_WRITEABLE);
                SharedPreferences.Editor editor2 = preferences2.edit();

                editor2.putString("tabselected",idal.get(0).toString());
                editor2.putString("Authentication_Status", "true");
                editor2.apply();

                setupViewPager(viewPager);
                tabLayout.setupWithViewPager(viewPager);
                setupTags();

            }
            else {
                Toast.makeText(ScrollableTabsActivity.this,r, Toast.LENGTH_SHORT).show();
            }
        }

        @Override
        protected String doInBackground(String... params) {

            try {
                Connection con = connectionClass.CONN();
                if (con == null) {
                    z = "Error in connection with SQL server";
                } else {
                    String query = "SELECT ID,Category_ItemName,Pi_Category_ID FROM [dbo].[MainMenuDetail] where Pi_Category_ID=0 and Delete_category=0";
                    Statement stmt = con.createStatement();
                    ResultSet rs = stmt.executeQuery(query);
                    while (rs.next())
                    {
                        idal.add(rs.getString("ID"));
                        al.add(rs.getString("Category_ItemName"));
                        pidal.add(rs.getString("Pi_Category_ID"));

                    }
                    z = "Successful";
                    isSuccess=true;
                }
            }
            catch (Exception ex)
            {
                isSuccess = false;
                z = "Exceptions";
            }

            return z;
        }

    }
}

public class MainActivity extends android.support.v4.app.Fragment {
	// Log tag

	private static final String TAG = MainActivity.class.getSimpleName();
	ConnectionClass connectionClass;
	// Movies json url
	String url="http://i.imgur.com/mQPXunb.png";
	private List<Movie> movieList = new ArrayList<Movie>();
	private ListView listView;
	private CustomListAdapter adapter;
	private List templist = new ArrayList();
	String image_url = "http://app.dartenogroup.com/admin/img/";
	String image_url2="";
	NetworkImageView img;
	String restid;
	Movie movie;
	String tabselected;


	@Override
	public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
		return inflater.inflate(R.layout.activity_main, container, false);
	}
	@Override
	public void onViewCreated(View view,Bundle savedInstanceState){
		super.onViewCreated(view,savedInstanceState);

		SharedPreferences prfs = getActivity().getSharedPreferences("AUTHENTICATION_FILE_NAME", Context.MODE_PRIVATE);
		restid = prfs.getString("restid", "");

		SharedPreferences prfs2 = getActivity().getSharedPreferences("AUTHENTICATION_FILE_NAME2", Context.MODE_PRIVATE);
		tabselected = prfs2.getString("tabselected", "");
		Toast.makeText(getActivity(), tabselected, Toast.LENGTH_SHORT).show();

		connectionClass = new ConnectionClass();
		listView = (ListView) view.findViewById(R.id.list);
		adapter = new CustomListAdapter(getActivity(), movieList);
		listView.setAdapter(adapter);

		img = (NetworkImageView) view.findViewById(R.id.thumbnail);

		// changing action bar color
		//getActionBar().setBackgroundDrawable(
		//	new ColorDrawable(Color.parseColor("#ffffff")));

		DoLogin  doLogin = new DoLogin();
		doLogin.execute("");


		listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
			@Override
			public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
				Intent i2 = new Intent(getActivity(), ViewProduct.class);
				TextView tv=(TextView)view.findViewById(R.id.itemid);
				i2.putExtra("value",tv.getText().toString());
				startActivity(i2);
			}
		});

	}


	/**
	 * On selecting action bar icons
	 * */
	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
		// Take appropriate action for each action item click
		switch (item.getItemId()) {
			case R.id.action_cart:
				cart();
				return true;

			default:
				return super.onOptionsItemSelected(item);
		}
	}

	/**
	 * Launching new activity
	 * */
	private void cart() {
		Intent i = new Intent(getActivity(), Cart.class);
		startActivity(i);
	}

	public class DoLogin extends AsyncTask<String,String,String>
	{
		String z = "";
		Boolean isSuccess = false;


		@Override
		protected void onPreExecute() {
			movieList.clear();
			templist.clear();
		}

		@Override
		protected void onPostExecute(String r) {


			if(isSuccess) {

				updatelist();
				Vibrator v = (Vibrator) getActivity().getSystemService(Context.VIBRATOR_SERVICE);
				v.vibrate(500);
			}
			else{
				Toast.makeText(getActivity(),z,Toast.LENGTH_SHORT).show();
			}
		}


		@Override
		protected String doInBackground(String... params) {

				try {
					Connection con = connectionClass.CONN ();
					if (con == null) {
						z = "Error in connection with SQL server";
					} else {

						String query = "select * from [dbo].[MainMenuDetail] WHERE Delete_category = 0 AND Pi_Category_ID ='"+tabselected+"'" ;
						Statement stmt = con.createStatement();
						ResultSet rs = stmt.executeQuery(query);

						while (rs.next()) {

							movie = new Movie();
							movie.setId(rs.getString("ID"));
							movie.setItemname(rs.getString("Category_ItemName"));
							movie.setDescription(rs.getString("Category_SHortDesc"));
							movie.setPrice(rs.getString("Category_Price"));
							image_url2=rs.getString("show_Image");
							String img= image_url+image_url2;
							movie.setThumbnailUrl(img);
							update();
						}
						z = "Successful";
						isSuccess=true;
					}
				}
				catch (Exception ex)
				{
					isSuccess = false;
					z = "Exceptions";
				}

			return z;
		}
	}

	public void updatelist(){
		new Handler(Looper.getMainLooper()).post(new Runnable() {
			@Override
			public void run() {
				movieList.addAll(templist);
				adapter.notifyDataSetChanged();
			}
		});
	}
	public void refreshlist(){

		new Handler(Looper.getMainLooper()).post(new Runnable() {
			@Override
			public void run() {
				adapter.notifyDataSetChanged();
			}
		});	}

	public void vacatelist(){
		new Handler(Looper.getMainLooper()).post(new Runnable() {
			@Override
			public void run() {
				movieList.clear();
			}
		});
	}

	public void update(){
		templist.add(movie);
	}

}

Answer 1

你可以试试这个

@Override
public void onTabSelected(TabLayout.Tab tab) {
    CharSequence numTab = tab.getTag().toString();
    SharedPreferences preferences2 = getSharedPreferences("AUTHENTICATION_FILE_NAME2", Context.MODE_WORLD_WRITEABLE);
    SharedPreferences.Editor editor2 = preferences2.edit();

    editor2.putString("tabselected",numTab.toString());
    editor2.putString("Authentication_Status", "true");
    editor2.apply();

    // super called last
    super.onTabSelected(tab);
}

或存储ViewPagerAdapter adapter＆＃34;全球＆＃34;在ScrollableTabsActivity之上（不仅仅在setupViewPager方法内）

ViewPagerAdapter adapter;

private void setupViewPager(ViewPager viewPager) {
    adapter = new ViewPagerAdapter(getSupportFragmentManager());
    //rest of your code
}

然后

@Override
public void onTabSelected(TabLayout.Tab tab) {
    // your current code
    adapter.notifyDataSetChanged(); //ViewPagerAdapter's adapter
}

Answer 2

对于此问题，可能有几种解决方法

1。）如果数据少，标签少并且可以增加，则一次加载所有数据

viewPager.setOffscreenPageLimit(noOfTabs);

2。）在用户可见后更新您的片段。

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    super.setUserVisibleHint(isVisibleToUser);
    if (isVisibleToUser){
        // load data
    }
}

希望会有所帮助。