搜索小工具,NullPointer？

Question

我在我的应用程序中实现搜索小部件时遇到问题.它似乎无法找到菜单项的"动作视图",但它正好找到该项目.

我四处寻找答案,并没有看到明确的解决方案.

这是我在XML中声明的菜单

<menu xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<item android:id="@+id/group_search_box"
    android:title="@string/search_label"
    android:icon="@drawable/ic_action_action_search"
    app:showAsAction="ifRoom|collapseActionView"
    app:actionViewClass="android.support.v7.widget.SearchView" />

以下是它的实现方式.

SearchManager searchManager = (SearchManager) getActivity().getSystemService(Context.SEARCH_SERVICE);
    MenuItem searchMenuItem = menu.findItem(R.id.group_search_box);
    SearchView searchView = (SearchView) searchMenuItem.getActionView();
    searchView.setSearchableInfo(searchManager.getSearchableInfo(getActivity().getComponentName()));

这是我正在添加的库,也许我添加了一个不正确的库？

compile 'com.android.support:support-v4:+'
compile 'com.android.support:appcompat-v7:+'

最后这里是崩溃日志

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.SearchView.setSearchableInfo(android.app.SearchableInfo)' on a null object reference
        at com.example.myapp.fragments.GroupFragment.onCreateOptionsMenu(GroupFragment.java:88)
        at android.app.Fragment.performCreateOptionsMenu(Fragment.java:1780)
        at android.app.FragmentManagerImpl.dispatchCreateOptionsMenu(FragmentManager.java:1927)
        at android.app.Activity.onCreatePanelMenu(Activity.java:2539)
        at android.support.v4.app.FragmentActivity.onCreatePanelMenu(FragmentActivity.java:224)
        at com.android.internal.policy.impl.PhoneWindow.preparePanel(PhoneWindow.java:436)
        at com.android.internal.policy.impl.PhoneWindow.doInvalidatePanelMenu(PhoneWindow.java:800)
        at com.android.internal.policy.impl.PhoneWindow$1.run(PhoneWindow.java:221)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
        at android.view.Choreographer.doCallbacks(Choreographer.java:574)
        at android.view.Choreographer.doFrame(Choreographer.java:543)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
        at android.os.Handler.handleCallback(Handler.java:733)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:136)
        at android.app.ActivityThread.main(ActivityThread.java:5017)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)

我已经跟着文档到了T,仍然无法弄清楚问题.

Answer 1

我今天遇到了同样的问题,摆脱了如下的困惑,

我也使用以下依赖项,

compile 'com.android.support:support-v4:+'
compile 'com.android.support:appcompat-v7:+'

这意味着我正在扩展活动类AppCompatActivity而不是Activity类.

所以在这段代码中,

SearchView searchView =
                (SearchView) menu.findItem(R.id.action_search).getActionView();
        searchView.setSearchableInfo(
                searchManager.getSearchableInfo(getComponentName()));

这个,SearchView应该是,android.support.v7.widget.SearchView而不是android.widget.SearchView.这就是你得到的原因,

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.SearchView.setSearchableInfo(android.app.SearchableInfo)' on a null object reference

并且,

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

请注意,它app:actionViewClass 不是 android:actionViewClass