O código no qual estou trabalhando está usando a Toolbare inflando a menu.

Aqui está o código

private Toolbar mToolbar;
mToolbar.inflateMenu(R.menu.chat_screen_menu);
setupMenu ();
private void setupMenu ()
   {
   mMenu = mToolbar.getMenu();
   if (mMenu != null)
      {
       if (mChatPager != null && mChatPager.getCurrentItem() > 0)
          {
          mMenu.setGroupVisible(R.id.menu_group_chats, true);
          mMenu.setGroupVisible(R.id.menu_group_contacts, false);
          }
       else
          {
           mMenu.setGroupVisible(R.id.menu_group_chats, false);
           mMenu.setGroupVisible(R.id.menu_group_contacts, true);
           mMenu.setGroupVisible(R.id.menu_group_otr_verified,false);
           mMenu.setGroupVisible(R.id.menu_group_otr_unverified,false);
           mMenu.setGroupVisible(R.id.menu_group_otr_off,false);
          }
    }
    mToolbar.setOnMenuItemClickListener(new OnMenuItemClickListener ()
    {
    ..........
    }
}

Mas agora, eles exigem um Searchbotão no tool_bar. Consegui colocar, segui um guia aqui. Quando tento escrever algo para pesquisar, o brinde que fiz para testar o listenernunca mostrado. o que indica que listenernão está funcionando

@Override
    public boolean onCreateOptionsMenu(Menu menu) {

    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.chat_screen_menu, menu);

    SearchManager searchManager = (SearchManager) getSystemService(Context.SEARCH_SERVICE);
    mSearchView = (SearchView) MenuItemCompat.getActionView(menu.findItem(R.id.action_menu_search));
    final Toast toast = new Toast(mApp);

    if (mSearchView != null )
    {
        mSearchView.setSearchableInfo(searchManager.getSearchableInfo(getComponentName()));
        mSearchView.setIconifiedByDefault(false);

        SearchView.OnQueryTextListener queryTextListener = new SearchView.OnQueryTextListener()
        {
            public boolean onQueryTextChange(String newText)
            {
                mSearchString = newText;
                //doFilterAsync(mSearchString);
                toast.makeText(getApplicationContext(), "Test1", Toast.LENGTH_LONG).show();
                return true;
            }

            public boolean onQueryTextSubmit(String query)
            {
                mSearchString = query;
                //doFilterAsync(mSearchString);
                toast.makeText(getApplicationContext(), "Test2", Toast.LENGTH_LONG).show();

                return true;
            }
        };

        mSearchView.setOnQueryTextListener(queryTextListener);
    }

    return true;

}

Você tem que usar a Appcompatbiblioteca para isso. Qual é usado como abaixo:

dashboard.xml

<menu xmlns:android="http://schemas.android.com/apk/res/android" 
      xmlns:tools="http://schemas.android.com/tools"
      xmlns:app="http://schemas.android.com/apk/res-auto">

    <item
        android:id="@+id/action_search"
        android:icon="@android:drawable/ic_menu_search"
        app:showAsAction="always|collapseActionView"
        app:actionViewClass="androidx.appcompat.widget.SearchView"
        android:title="Search"/>
</menu>

Arquivo de atividade (em Java):

public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater menuInflater = getMenuInflater();
    menuInflater.inflate(R.menu.dashboard, menu);

     MenuItem searchItem = menu.findItem(R.id.action_search);

    SearchManager searchManager = (SearchManager) MainActivity.this.getSystemService(Context.SEARCH_SERVICE);

    SearchView searchView = null;
    if (searchItem != null) {
        searchView = (SearchView) searchItem.getActionView();
    }
    if (searchView != null) {
        searchView.setSearchableInfo(searchManager.getSearchableInfo(MainActivity.this.getComponentName()));
    }
        return super.onCreateOptionsMenu(menu);
}

Arquivo de atividade (em Kotlin):

override fun onCreateOptionsMenu(menu: Menu?): Boolean {
    menuInflater.inflate(R.menu.menu_search, menu)

    val searchItem: MenuItem? = menu?.findItem(R.id.action_search)
    val searchManager = getSystemService(Context.SEARCH_SERVICE) as SearchManager
    val searchView: SearchView? = searchItem?.actionView as SearchView

    searchView?.setSearchableInfo(searchManager.getSearchableInfo(componentName))
    return super.onCreateOptionsMenu(menu)
}

arquivo de manifesto:

<meta-data 
      android:name="android.app.default_searchable" 
      android:value="com.apkgetter.SearchResultsActivity" /> 

        <activity
            android:name="com.apkgetter.SearchResultsActivity"
            android:label="@string/app_name"
            android:launchMode="singleTop" >
            <intent-filter>
                <action android:name="android.intent.action.SEARCH" />
            </intent-filter>
            <intent-filter>
                <action android:name="android.intent.action.VIEW" />
            </intent-filter>

            <meta-data
                android:name="android.app.searchable"
                android:resource="@xml/searchable" />
        </activity>

arquivo xml pesquisável:

<?xml version="1.0" encoding="utf-8"?>
<searchable xmlns:android="http://schemas.android.com/apk/res/android"
    android:hint="@string/search_hint"
    android:label="@string/app_name" />

E, finalmente, o seu SearchResultsActivitycódigo de classe. para mostrar o resultado da sua pesquisa.

Se você deseja configurar o recurso de pesquisa dentro do seu Fragment, basta adicionar estas poucas linhas:

Etapa 1 - adicione o campo de pesquisa para você toolbar:

<item
    android:id="@+id/action_search"
    android:icon="@android:drawable/ic_menu_search"
    app:showAsAction="always|collapseActionView"
    app:actionViewClass="android.support.v7.widget.SearchView"
    android:title="Search"/>

Etapa 2 - adicione a lógica ao seuonCreateOptionsMenu()

import android.support.v7.widget.SearchView; // not the default !

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

    MenuItem myActionMenuItem = menu.findItem( R.id.action_search);
    searchView = (SearchView) myActionMenuItem.getActionView();
    searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
        @Override
        public boolean onQueryTextSubmit(String query) {
            // Toast like print
            UserFeedback.show( "SearchOnQueryTextSubmit: " + query);
            if( ! searchView.isIconified()) {
                searchView.setIconified(true);
            }
            myActionMenuItem.collapseActionView();
            return false;
        }
        @Override
        public boolean onQueryTextChange(String s) {
            // UserFeedback.show( "SearchOnQueryTextChanged: " + s);
            return false;
        }
    });
    return true;
}

Se você deseja adicioná-lo diretamente na barra de ferramentas.

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.AppBarLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <android.support.v7.widget.Toolbar
        android:id="@+id/app_bar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <SearchView
            android:id="@+id/searchView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:iconifiedByDefault="false"
            android:queryHint="Search"
            android:layout_centerHorizontal="true" />

    </android.support.v7.widget.Toolbar>

</android.support.design.widget.AppBarLayout>

Integrando o SearchView ao RecyclerView

1) Adicionar item de pesquisa no menu

SearchViewpode ser adicionado como actionViewno menu usando

app: useActionClass = "android.support.v7.widget.SearchView".

<menu xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
tools:context="rohksin.com.searchviewdemo.MainActivity">
<item
    android:id="@+id/searchBar"
    app:showAsAction="always"
    app:actionViewClass="android.support.v7.widget.SearchView"
    />
</menu>

2) Implemente SearchView.OnQueryTextListener em sua atividade

SearchView.OnQueryTextListenertem dois métodos abstratos. Portanto, seu esqueleto de atividade ficaria assim depois de implementar o ouvinte de texto do SearchView.

YourActivity extends AppCompatActivity implements SearchView.OnQueryTextListener{

   public boolean onQueryTextSubmit(String query)

   public boolean onQueryTextChange(String newText) 

}

3) Configure o texto do SerchView Hint, o ouvinte etc.

@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_main, menu);

    MenuItem searchItem = menu.findItem(R.id.searchBar);

    SearchView searchView = (SearchView) searchItem.getActionView();
    searchView.setQueryHint("Search People");
    searchView.setOnQueryTextListener(this);
    searchView.setIconified(false);

    return true;
}

4) Implemente SearchView.OnQueryTextListener

É assim que você pode implementar métodos abstratos do ouvinte.

@Override
public boolean onQueryTextSubmit(String query) {

    // This method can be used when a query is submitted eg. creating search history using SQLite DB

    Toast.makeText(this, "Query Inserted", Toast.LENGTH_SHORT).show();
    return true;
}

@Override
public boolean onQueryTextChange(String newText) {

    adapter.filter(newText);
    return true;
}

5) Escreva um método de filtro no seu adaptador RecyclerView.

Você pode criar sua própria lógica com base em seus requisitos. Aqui está o trecho de código de exemplo para mostrar a lista de Nome que contém o texto digitado no SearchView.

public void filter(String queryText)
{
    list.clear();

    if(queryText.isEmpty())
    {
        list.addAll(copyList);
    }
    else
    {

        for(String name: copyList)
        {
            if(name.toLowerCase().contains(queryText.toLowerCase()))
            {
                list.add(name);
            }
        }

    }

    notifyDataSetChanged();
}

Pode ser encontrada uma amostra completa do código de funcionamento> AQUI
Você também pode verificar o código no SearchView com um banco de dados SQLite neste aplicativo de música

Implementando o SearchView sem o uso do menu.xmlarquivo e aberto através do botão

No seu caso Activity, precisamos usar o método do onCreateOptionsMenumétodo no qual inflaremos programaticamente oSearchView

private MenuItem searchMenu;
private String mSearchString="";

@Override
    public boolean onCreateOptionsMenu(Menu menu) {
        super.onCreateOptionsMenu(menu);

        SearchManager searchManager = (SearchManager) StoreActivity.this.getSystemService(Context.SEARCH_SERVICE);


        SearchView mSearchView = new SearchView(getSupportActionBar().getThemedContext());
        mSearchView.setQueryHint(getString(R.string.prompt_search)); /// YOUR HINT MESSAGE
        mSearchView.setMaxWidth(Integer.MAX_VALUE);

        searchMenu = menu.add("searchMenu").setVisible(false).setActionView(mSearchView);
        searchMenu.setShowAsAction(MenuItem.SHOW_AS_ACTION_IF_ROOM | MenuItem.SHOW_AS_ACTION_COLLAPSE_ACTION_VIEW);


        assert searchManager != null;
        mSearchView.setSearchableInfo(searchManager.getSearchableInfo(getComponentName()));
        mSearchView.setIconifiedByDefault(false);

        SearchView.OnQueryTextListener queryTextListener = new SearchView.OnQueryTextListener() {
            public boolean onQueryTextChange(String newText) {
                mSearchString = newText;

                return true;
            }

            public boolean onQueryTextSubmit(String query) {
                mSearchString = query;

                searchMenu.collapseActionView();


                return true;
            }
        };

        mSearchView.setOnQueryTextListener(queryTextListener);


        return true;
    }

E na sua classe Atividade, você pode abrir o SearchViewbotão em qualquer botão, na barra de ferramentas, como abaixo

YOUR_BUTTON.setOnClickListener(view -> {

            searchMenu.expandActionView();

        });