android - Material SearchView 实现错误

Question

我正在开发一个 Android 应用程序，现在一切都很好，但是当尝试使用 Google 指南实现 Material SearchView 并逐步遵循一些教程时，我无法弄清楚这个错误:

menu_main.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <item
        android:id="@+id/search_ad"
        android:enabled="true"
        android:icon="@android:drawable/ic_menu_search"
        android:title="Buscar"
        android:visible="true"
        app:actionViewClass="android.support.v7.widget.SearchView"
        app:showAsAction="ifRoom|collapseActionView" />

    <item
        android:id="@+id/publish_ad"
        android:enabled="true"
        android:icon="@android:drawable/ic_menu_send"
        android:title="Publicar anuncio"
        android:visible="true"
        app:showAsAction="never" />

    <item
        android:id="@+id/favs"
        android:enabled="true"
        android:title="Configuración"
        android:visible="true"
        app:showAsAction="never" />
</menu>

主要 Activity

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

    SearchManager searchManager = (SearchManager) getSystemService(Context.SEARCH_SERVICE);
    SearchView searchView = (SearchView) menu.findItem(R.id.search_ad).getActionView();
    searchView.setSearchableInfo(searchManager.getSearchableInfo(getComponentName()));
    searchView.setIconifiedByDefault(false);

    return true;
}

错误:

06-16 15:36:51.021 1239-1239/com.bachecubano.elbache E/AndroidRuntime: FATAL EXCEPTION: main
   Process: com.bachecubano.elbache, PID: 1239
   java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.SearchView.setSearchableInfo(android.app.SearchableInfo)' on a null object reference
       at com.bachecubano.elbache.MainActivity.onCreateOptionsMenu(Unknown Source)
       at android.app.Activity.onCreatePanelMenu(Activity.java:2889)
       at android.support.v4.b.m.onCreatePanelMenu(Unknown Source)
       at android.support.v7.view.i.onCreatePanelMenu(Unknown Source)
       at android.support.v7.app.h$b.onCreatePanelMenu(Unknown Source)
       at android.support.v7.view.i.onCreatePanelMenu(Unknown Source)
       at android.support.v7.app.q.j(Unknown Source)
       at android.support.v7.app.q$1.run(Unknown Source)
       at android.os.Handler.handleCallback(Handler.java:815)
       at android.os.Handler.dispatchMessage(Handler.java:104)
       at android.os.Looper.loop(Looper.java:207)
       at android.app.ActivityThread.main(ActivityThread.java:5692)
       at java.lang.reflect.Method.invoke(Native Method)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:908)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:769)

Answer 1

您是否在 list 中添加了以下代码:

<activity
    android:name=".ActivityWhereYouWantYourSearch">
    ...
    <intent-filter>
        <action android:name="android.intent.action.SEARCH" />
    </intent-filter>

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

在您的 res/xml 文件夹中(名为 searchable.xml):

<?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"
    android:searchSettingsDescription="@string/search_description" />

我还将检查您的 onCreateOptionsMenu，如下所示:

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

    MenuItem searchItem = menu.findItem(R.id.search_ad);
    if (searchItem != null) {
        SearchManager searchManager = (SearchManager)getSystemService(Context.SEARCH_SERVICE);
        SearchView searchView = (SearchView) searchItem.getActionView();
        // Assumes current activity is the searchable activity
        searchView.setSearchableInfo(searchManager.getSearchableInfo(getComponentName()));
        searchView.setIconifiedByDefault(false); // Do not iconify the widget; expand it by default
    }
    return true;
}

顺便说一句，我不使用 android:enabled 和 android:visible，但这由您决定。