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我试图将搜索图标添加到按下的工具栏中将打开搜索栏。为什么setOnQueryTextListener（）获取“空对象引用”错误？
但每次我试过的方法没有工作，不显示图标。 现在，我得到这个错误，只是找不到解决的办法：
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.widget.SearchView.setOnQueryTextListener(android.support.v7.widget.SearchView$OnQueryTextListener)' on a null object reference
at pl.michalz.hideonscrollexample.activity.partthree.PartThreeActivity.onCreateOptionsMenu(PartThreeActivity.java:62)
这是我主要活动：
public class PartThreeActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
setTheme(R.style.AppThemeBlue);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_part_three);
initToolbar();
initViewPagerAndTabs();
}
@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 seachItem = menu.findItem(R.id.action_search);
SearchView searchView = (SearchView)
MenuItemCompat.getActionView(seachItem);
searchView.setOnQueryTextListener(
new SearchView.OnQueryTextListener(){
@Override
public boolean onQueryTextSubmit(String query) {
Log.d("myApp", "onQueryTextSubmit ");
return false;
}
@Override
public boolean onQueryTextChange(String newText) {
Log.d("myApp", "onQueryTextChange ");
return false;
}
});
return true;
}
private void initToolbar() {
Toolbar mToolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(mToolbar);
setTitle(getString(R.string.app_name));
mToolbar.setTitleTextColor(getResources().getColor(android.R.color.white));
}
private void initViewPagerAndTabs() {
ViewPager viewPager = (ViewPager) findViewById(R.id.viewPager);
PagerAdapter pagerAdapter = new PagerAdapter(getSupportFragmentManager());
pagerAdapter.addFragment(PartThreeFragment.createInstance(), getString(R.string.tab_1));
pagerAdapter.addFragment(BlankFragment.createInstance("F word"), getString(R.string.tab_2));
viewPager.setAdapter(pagerAdapter);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tabLayout);
tabLayout.setupWithViewPager(viewPager);
}
static class PagerAdapter extends FragmentPagerAdapter {
private final List<Fragment> fragmentList = new ArrayList<>();
private final List<String> fragmentTitleList = new ArrayList<>();
public PagerAdapter(FragmentManager fragmentManager) {
super(fragmentManager);
}
public void addFragment(Fragment fragment, String title) {
fragmentList.add(fragment);
fragmentTitleList.add(title);
}
@Override
public Fragment getItem(int position) {
return fragmentList.get(position);
}
@Override
public int getCount() {
return fragmentList.size();
}
@Override
public CharSequence getPageTitle(int position) {
return fragmentTitleList.get(position);
}
}
//kai paskaudzia toolbaro iconas
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.action_settings:
// User chose the "Settings" item, show the app settings UI...
return true;
case R.id.action_search:
// User chose the "Favorite" action, mark the current item
// as a favorite...
return true;
default:
// If we got here, the user's action was not recognized.
// Invoke the superclass to handle it.
return super.onOptionsItemSelected(item);
}
}
}
主要Activity.xml
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/coordinatorLayout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.design.widget.AppBarLayout
android:id="@+id/appBarLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:layout_scrollFlags="scroll|enterAlways|snap" />
<android.support.design.widget.TabLayout
android:id="@+id/tabLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:tabIndicatorColor="@android:color/white"
app:tabIndicatorHeight="6dp"
app:tabSelectedTextColor="@android:color/white"
app:tabTextColor="@android:color/white" />
</android.support.design.widget.AppBarLayout>
<android.support.v4.view.ViewPager
android:id="@+id/viewPager"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior" />
</android.support.design.widget.CoordinatorLayout>
另外searchable.xml
<searchable xmlns:android="http://schemas.android.com/apk/res/android"
android:hint="@string/hint"
android:label="@string/app_name" />
而且RES /菜单/ menu_main.xml，加入ic_search自己绘制
<menu xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/tools">
<item
android:id="@+id/action_search"
android:icon="@drawable/ic_search"
android:title="@string/action_search"
app:actionViewClass="android.support.v7.widget.SearchView"
app:showAsAction="ifRoom|collapseActionView" />
<!-- Settings, should always be in the overflow -->
<item
android:id="@+id/action_settings"
android:title="@string/action_settings"
app:showAsAction="never" />
</menu>
有人能帮忙吗？