java.util.ConcurrentModificationException in fragment : <p>I am developing android app I have implemented searchview but when I start to search news in search bar </p>

<pre><code>I am getting following exception 
</code></pre>

<blockquote>
  <p>Process: edgar.yodgorbek.sportnews, PID: 5146
          java.util.ConcurrentModificationException
              at java.util.ArrayList$Itr.next(ArrayList.java:860)
              at edgar.yodgorbek.sportnews.sportactivities.BBCSportFragment.doFilter(BBCSportFragment.java:126)
              at edgar.yodgorbek.sportnews.MainActivity$1.onQueryTextChange(MainActivity.java:126)</p>
</blockquote>

<p>below BBCSportFragment.java</p>

<pre><code>public class BBCSportFragment extends Fragment implements ArticleAdapter.ClickListener {

    public static List&lt;Article&gt; articleList = new ArrayList&lt;&gt;();
    public List&lt;Search&gt; searchList = new ArrayList&lt;&gt;();
    @ActivityContext
    public Context activityContext;
    Search search;
    @ApplicationContext
    public Context mContext;

    @BindView(R.id.recycler_view)
    RecyclerView recyclerView;
    BBCSportFragmentComponent bbcSportFragmentComponent;
    BBCFragmentContextModule bbcFragmentContextModule;
    private SportNews sportNews;
    private static ArticleAdapter articleAdapter;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_bbcsport, container, false);
        ButterKnife.bind(this, view);
        SportInterface sportInterface = SportClient.getApiService();
        Call&lt;SportNews&gt; call = sportInterface.getArticles();
        call.enqueue(new Callback&lt;SportNews&gt;() {
            @Override
            public void onResponse(Call&lt;SportNews&gt; call, Response&lt;SportNews&gt; response) {
                if (response == null) {
                    sportNews = response.body();
                    if (sportNews != null &amp;&amp; sportNews.getArticles() != null) {
                        articleList.addAll(sportNews.getArticles());
                    }
                    articleAdapter = new ArticleAdapter(articleList, sportNews);
                    ApplicationComponent applicationComponent;
                    applicationComponent = (ApplicationComponent) MyApplication.get(Objects.requireNonNull(getActivity())).getApplicationContext();
                    bbcSportFragmentComponent = (BBCSportFragmentComponent) DaggerApplicationComponent.builder().contextModule(new ContextModule(getContext())).build();
                    bbcSportFragmentComponent.injectBBCSportFragment(BBCSportFragment.this);
                    RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getContext(applicationComponent));
                    recyclerView.setLayoutManager(layoutManager);
                    recyclerView.setAdapter(articleAdapter);
                }
            }

            @Override
            public void onFailure(Call&lt;SportNews&gt; call, Throwable t) {

            }
        });


        SportInterface searchInterface = SportClient.getApiService();
        Call&lt;Search&gt; searchCall = searchInterface.getSearchViewArticles("q");
         searchCall.enqueue(new Callback&lt;Search&gt;() {
             @Override
             public void onResponse(Call&lt;Search&gt; call, Response&lt;Search&gt; response) {
                 search = response.body();

                 if (search != null &amp;&amp; search.getArticles() != null) {
                     articleList.addAll(search.getArticles());
                 }

                 articleAdapter = new ArticleAdapter(articleList, search);
                 RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getContext());
                 recyclerView.setLayoutManager(layoutManager);
                 recyclerView.setAdapter(articleAdapter);
             }

             @Override
             public void onFailure(Call&lt;Search&gt; call, Throwable t) {

             }
         });


        return view;


    }

    private Context getContext(ApplicationComponent applicationComponent) {
        return null;
    }

    public static void doFilter(String searchQuery) {
       searchQuery = searchQuery.toLowerCase();

        for(Article article:  articleList){
            final String text = "";
            if (text.equals(searchQuery))
                articleList.add(article);
        }
         articleList.clear();
        if(articleList.isEmpty())
     articleAdapter.notifyDataSetChanged();

    }
}
</code></pre>

<p>below MainActivity.java</p>

<pre><code>public class MainActivity extends AppCompatActivity {
    private DrawerLayout mDrawer;
    private Toolbar toolbar;
    private NavigationView nvDrawer;
    private ActionBarDrawerToggle drawerToggle;
    Context mContext;

    // Default active navigation menu
    int mActiveMenu;

    // TAGS
    public static final int MENU_FIRST = 0;
    public static final int MENU_SECOND = 1;
    public static final int MENU_THIRD = 2;
    public static final int MENU_FOURTH = 3;
    public static final int MENU_FIFTH = 3;
    public static final String TAG = "crash";


    // Action bar search widget
    SearchView searchView;
    String searchQuery = "";


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

        // Set a Toolbar to replace the ActionBar.
        toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        // Find our drawer view
        mDrawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawerToggle = setupDrawerToggle();

        // Tie DrawerLayout events to the ActionBarToggle
        mDrawer.addDrawerListener(drawerToggle);

        nvDrawer = (NavigationView) findViewById(R.id.nvView);

// Inflate the header view at runtime
        View headerLayout = nvDrawer.inflateHeaderView(R.layout.nav_header);
// We can now look up items within the header if needed
        ImageView ivHeaderPhoto = (ImageView) headerLayout.findViewById((R.id.header_image));
        ivHeaderPhoto.setImageResource(R.drawable.ic_sportnews);
        setupDrawerContent(nvDrawer);
        FragmentManager fragmentManager = getSupportFragmentManager();
        fragmentManager.beginTransaction().replace(R.id.flContent, new BBCSportFragment()).commit();
        fragmentManager.beginTransaction().replace(R.id.flContent, new FoxSportsFragment()).commit();
        fragmentManager.beginTransaction().replace(R.id.flContent, new TalkSportsFragment()).commit();

    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // The action bar home/up action should open or close the drawer.
        switch (item.getItemId()) {
            case android.R.id.home:
                mDrawer.openDrawer(GravityCompat.START);
                return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu, menu);

        // Getting search action from action bar and setting up search view
        MenuItem searchItem = menu.findItem(R.id.action_search);
        SearchView searchView = (SearchView) searchItem.getActionView();

        // Setup searchView
        setupSearchView(searchView);
        Log.e(TAG,"crash");
        return true;
    }

    public void setupSearchView(SearchView searchView) {
        SearchManager searchManager = (SearchManager) this.getSystemService(Context.SEARCH_SERVICE);
        if (searchManager != null) {
            SearchableInfo info = searchManager.getSearchableInfo(getComponentName());
            searchView.setSearchableInfo(info);
        }

        searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
            @Override
            public boolean onQueryTextChange(String newText) {
                searchQuery = newText;

                // Load search data on respective fragment
                if (mActiveMenu == MENU_FIRST)   // First
                {
                    BBCSportFragment.doFilter(newText);
                }

                if (mActiveMenu == MENU_SECOND)   // First
                {
                    BBCSportFragment.doFilter(newText);
                }

                if (mActiveMenu == MENU_THIRD)   // First
                {
                    BBCSportFragment.doFilter(newText);
                }

                if (mActiveMenu == MENU_FOURTH)   // First
                {
                    BBCSportFragment.doFilter(newText);
                } else if (mActiveMenu == MENU_FIFTH) // Second
                {
                    ESPNFragment.doFilter(newText);
                }
                return true;
            }

            @Override
            public boolean onQueryTextSubmit(String query) {
                //searchView.clearFocus();
                return false;
            }
        });

        // Handling focus change of search view
        searchView.setOnQueryTextFocusChangeListener(new View.OnFocusChangeListener() {

            @Override
            public void onFocusChange(View v, boolean hasFocus) {

                // Focus changed after pressing back key or pressing done in keyboard
                if (!hasFocus) {
                    searchQuery = "";
                }
            }
        });
    }


    private void setupDrawerContent(NavigationView navigationView) {
        navigationView.setNavigationItemSelectedListener(
                menuItem -&gt; {
                    selectDrawerItem(menuItem);
                    return true;
                });
    }

    public void selectDrawerItem(MenuItem menuItem) {
        // Create a new fragment and specify the fragment to show based on nav item clicked
        Fragment fragment = null;
        Class fragmentClass = null;
        switch (menuItem.getItemId()) {
            case R.id.bbcsports_fragment:
                fragmentClass = BBCSportFragment.class;
                break;
            case R.id.talksports_fragment:
                fragmentClass = TalkSportsFragment.class;
                break;
            case R.id.foxsports_fragment:
                fragmentClass = FoxSportsFragment.class;
                break;

            case R.id.footballitalia_fragment:
                fragmentClass = FootballItaliaFragment.class;
                break;

            case R.id.espn_fragment:
                fragmentClass = ESPNFragment.class;
                break;

            default:

        }

        try {
            fragment = (Fragment) fragmentClass.newInstance();
        } catch (Exception e) {
            e.printStackTrace();
        }

        // Insert the fragment by replacing any existing fragment

        FragmentManager fragmentManager = getSupportFragmentManager();
        fragmentManager.beginTransaction().replace(R.id.flContent, fragment).commit();
        // Highlight the selected item has been done by NavigationView
        menuItem.setChecked(true);
        // Set action bar title
        setTitle(menuItem.getTitle());
        // Close the navigation drawer
        mDrawer.closeDrawers();
    }

    private ActionBarDrawerToggle setupDrawerToggle() {
        // NOTE: Make sure you pass in a valid toolbar reference.  ActionBarDrawToggle() does not require it
        // and will not render the hamburger icon without it.
        return new ActionBarDrawerToggle(this, mDrawer, toolbar, R.string.drawer_open, R.string.drawer_close);
    }


    @Override
    protected void onPostCreate(Bundle savedInstanceState) {
        super.onPostCreate(savedInstanceState);
        // Sync the toggle state after onRestoreInstanceState has occurred.
        drawerToggle.syncState();
    }

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        // Pass any configuration change to the drawer toggles
        drawerToggle.onConfigurationChanged(newConfig);
    }


}
</code></pre>
