我正在构建一个简单的股票显示应用程序，允许您获取感兴趣的股票（frag A），将它们存储在TinyDB中，并将它们显示在recyclerView（frag B）中。
该框架曾经工作正常 - 直到我决定合并一个viewpager和Tablayout主机。我无法在Frag B中获得RecyclerView来实时显示新数据。这是因为活动viewpager在启动时初始化两个片段，这意味着你不能再次调用onCreateView代码了。我相信。
通过活动在两个片段之间进行通信已经在本网站上进行过触摸，但我找到了最好的例子：
（https://github.com/kylejablonski/InterfaceDemo），
使用两个接口，一个用于从Frag A到Activity进行通信，另一个用于从Activity到Frag B进行通信。但是我遇到了严重的问题 -
<%= Category.find_by(name: 'test').locations.count %>
Frag A（MainFragment） （https://github.com/EXJUSTICE/Investr/blob/master/app/src/main/java/com/xu/investo/MainFragment.java）
public class ViewHolderActivity extends AppCompatActivity implements CommunicateToActivity,CommunicateToFragment{
//Job of ViewHolderActivity is to allow swiping between list and MainFragment/Fragment
TabLayout tablayout;
ViewPager viewPager;
List<HistoricalQuote> historicaldata;
Bundle bundle;
Adapter adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view_holder);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
viewPager =(ViewPager)findViewById(R.id.viewpager);
tablayout= (TabLayout)findViewById(R.id.tabs);
tablayout.setupWithViewPager(viewPager);
setupViewPager(viewPager);
viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
}
@Override
public void onPageScrollStateChanged(int state) {
}
});
}
//----------------------- Interface code-----------
@Override
public void communicateup(){
communicatedown();
//call communicate down STRAIGHT, since we call it from mainfrag
}
@Override
public void communicatedown(){
//This line works
ListFragment currentFragment =(ListFragment)adapter.instantiateItem(viewPager,1);
currentFragment.refreshUI();
}
private void setupViewPager(ViewPager viewPager) {
adapter = new Adapter(getSupportFragmentManager());
adapter.addFragment(new MainFragment(), "Add Stock");
adapter.addFragment(new ListFragment(), "Portfolio");
viewPager.setAdapter(adapter);
}
static class Adapter extends FragmentPagerAdapter {
private final List<Fragment> mFragmentList = new ArrayList<>();
private final List<String> mFragmentTitleList = new ArrayList<>();
public Adapter(FragmentManager manager) {
super(manager);
}
@Override
public Fragment getItem(int position) {
return mFragmentList.get(position);
}
@Override
public int getCount() {
return mFragmentList.size();
}
public void addFragment(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
@Override
public CharSequence getPageTitle(int position) {
return mFragmentTitleList.get(position);
}
}
Frag B（ListFragment） （https://github.com/EXJUSTICE/Investr/blob/master/app/src/main/java/com/xu/investo/ListFragment.java）
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
View view =inflater.inflate(R.layout.content_main,container,false);
stocknames = new ArrayList<String>();
stocktickers = new ArrayList<String>();
tinyDB = new TinyDB(getContext());
/*
menu.setDisplayShowHomeEnabled(true);
//menu.setLogo("INSERT LOGO HERE");
menu.setDisplayUseLogoEnabled(true);
menu.setTitle(" Stock Selector");
*/
fetch =(Button) view.findViewById(R.id.fetchBtn);
enterID =(EditText)view.findViewById(R.id.enterID);
display =(TextView)view.findViewById(R.id.display);
mCalendar = Calendar.getInstance();
clear = (Button)view.findViewById(R.id.clearportfolio);
fetch.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//TODO all the main page should do is add stocktickers and names to portfolio
//Fetch id and the dates
id =enterID.getText().toString();
/*to = Calendar.getInstance();
from = Calendar.getInstance();
to.setTime(dateto);
from.setTime(datefrom);
*/
FetchXDayData getData = new FetchXDayData();
getData.execute(id);
}
});
clear.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View view) {
tinyDB.clear();
recyclerinterface.communicateup();
}
});
return view;
}
//----------------------------INTERFACE CODE
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
// This makes sure that the container activity has implemented
// the callback interface. If not, it throws an exception
try {
recyclerinterface = (CommunicateToActivity) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement RecyclerUpdateInterface");
}
}
///-------End of Oncreate---------------------------------------------------------------
//Called by AsyncTask, moving result to main thread
public void moveResultToUI(Stock result){
this.stock = result;
Toast.makeText(getActivity(),"Stock "+stock.getName()+" successfully added to portofolio",Toast.LENGTH_LONG).show();
//reverse the list of course, stock names and tickrs to portfolio
stocknames.add(stock.getName());
stocktickers.add(stock.getSymbol());
/*DEBUG Test code, Test. 30012017 WORKS
for (int i =0;i<historicaldata.size();i++){
HistoricalQuote current = historicaldata.get(i);
Toast toast = Toast.makeText(this,current.getClose().toString(),Toast.LENGTH_SHORT);
toast.show();
}
*/
//
if (stock != null){
display.setText("Name: "+stock.getName() +"\n"+"Price: "+ stock.getQuote().getPrice()+"\n"+ "Change(%)"+stock.getQuote().getChangeInPercent());
/*SMA = getSMA(10);
decision=checkSimpleCrossover(SMA,stock.getQuote().getPrice().longValue());
decisionView.setText("SMA: " + SMA + "\n"+decision);
*/
tinyDB.putListString("names",stocknames);
tinyDB.putListString("tickers",stocktickers);
//call interface activity comming up to Activity, then down to next fragment
recyclerinterface.communicateup();
}else{
Toast error = Toast.makeText(getActivity(),"Network Problem",Toast.LENGTH_SHORT);
error.show();
}
}
提前致谢。
编辑：通过创建新的适配器并将其链接到从TinyDB中提取的新arraylists来解决问题，从而有效地交换适配器。
答案 0 :(得分：0)
通过创建一个全新的RecyclerView适配器解决了这个问题，新的arraylist数据绑定到该适配器，然后将整个recyclerview设置为使用这个新的适配器。所有这一切都是从FragA一步完成的，使用解决方案中代码中显示的接口。
如下所示的方法：
public void refreshUI(){
tinyDB = null;
tinyDB = new TinyDB(getContext());
newnames = tinyDB.getListString("names");
newtickers= tinyDB.getListString("tickers");
mAdapter = new StockAdapter(newnames,newtickers);
recyclerView.setAdapter(mAdapter);
}