新手求助，改造以前的谷歌记事本demo，为其添加一个SearchView,给SearchView加上监听器程序就停止运行，以下java代码只贴出onCreateOptionsMenu和 onOptionsItemSelected方法。第一次用searchView，出错了不知道该怎么改 以下为主activity类NotesList,问题出在这个类中，其他类就不贴出了package com.example.android.notepad;import com.example.android.notepad.NotePad;import android.app.ListActivity;
import android.content.ClipboardManager;
import android.content.ClipData;
import android.content.ComponentName;
import android.content.ContentUris;
import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.view.MenuItemCompat;
import android.util.Log;
import android.view.ContextMenu;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ContextMenu.ContextMenuInfo;
import android.support.v7.widget.SearchView;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
public class NotesList extends ListActivity {
SearchView mSearchView; private static final String TAG = "NotesList";
private static final String[] PROJECTION = new String[] {
NotePad.Notes._ID, // 0
NotePad.Notes.COLUMN_NAME_TITLE, // 1
NotePad.Notes.COLUMN_NAME_CREATE_DATE
}; private static final int COLUMN_INDEX_TITLE = 1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState); setDefaultKeyMode(DEFAULT_KEYS_SHORTCUT);
setContentView(R.layout.main_layout); Intent intent = getIntent(); if (intent.getData() == null) {
intent.setData(NotePad.Notes.CONTENT_URI);
}
getListView().setOnCreateContextMenuListener (this);
Cursor cursor = managedQuery(
getIntent().getData(), // Use the default content URI for the provider.
PROJECTION, // Return the note ID and title for each note.
null, // No where clause, return all records.
null, // No where clause, therefore no where column values.
NotePad.Notes.DEFAULT_SORT_ORDER // Use the default sort order.
);
String[] dataColumns = { NotePad.Notes.COLUMN_NAME_TITLE,NotePad.Notes.COLUMN_NAME_CREATE_DATE} ; int[] viewIDs = { android.R.id.text1 ,android.R.id.text2}; // Creates the backing adapter for the ListView.
SimpleCursorAdapter adapter
= new SimpleCursorAdapter(
this, // The Context for the ListView
R.layout.noteslist_item, // Points to the XML for a list item
cursor, // The cursor to get items from
dataColumns,
viewIDs
);
setListAdapter(adapter);
} @Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.list_options_menu, menu);
//添加SearchView的代码开始
MenuItem mMenuItem = menu.findItem(R.id.search);
mSearchView=(android.support.v7.widget.SearchView) MenuItemCompat.getActionView(mMenuItem);
mSearchView.setOnQueryTextListener(new SearchView.OnQueryTextListener(){
@Override
public boolean onQueryTextSubmit(String query){
return false;
}
@Override
public boolean onQueryTextChange(String newText){
return false;
}
}); // 添加SearchView的部分结束
Intent intent = new Intent(null, getIntent().getData());
intent.addCategory(Intent.CATEGORY_ALTERNATIVE);
menu.addIntentOptions(Menu.CATEGORY_ALTERNATIVE, 0, 0,
new ComponentName(this, NotesList.class), null, intent, 0, null); return super.onCreateOptionsMenu(menu);
} @Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.menu_add: startActivity(new Intent(Intent.ACTION_INSERT, getIntent().getData()));
return true;
case R.id.menu_paste: startActivity(new Intent(Intent.ACTION_PASTE, getIntent().getData()));
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}菜单布局文件
<?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">
<!-- This is our one standard application action (creating a new note). -->
<item
android:id="@+id/search"
android:actionViewClass="android.support.v7.widget.SearchView"
android:icon="@android:drawable/ic_menu_search"
android:orderInCategory="100"
android:title="搜索"
android:showAsAction="always|collapseActionView" />
<item android:id="@+id/menu_add"
android:icon="@drawable/ic_menu_compose"
android:title="@string/menu_add"
android:alphabeticShortcut='a'
android:showAsAction="always" />
<!-- If there is currently data in the clipboard, this adds a PASTE menu item to the menu
so that the user can paste in the data.. -->
<item android:id="@+id/menu_paste"
android:icon="@drawable/ic_menu_compose"
android:title="@string/menu_paste"
android:alphabeticShortcut='p' />
</menu>
以下报错信息
05-08 23:28:15.460 15959-15959/com.example.android.notepad E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.android.notepad, PID: 15959
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 com.example.android.notepad.NotesList.onCreateOptionsMenu(NotesList.java:98)
at android.app.Activity.onCreatePanelMenu(Activity.java:2820)
at com.android.internal.policy.impl.PhoneWindow.preparePanel(PhoneWindow.java:548)
at com.android.internal.policy.impl.PhoneWindow.doInvalidatePanelMenu(PhoneWindow.java:917)
at com.android.internal.policy.impl.PhoneWindow$1.run(PhoneWindow.java:258)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
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其中常见问题1就是解决空指针异常的
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu, menu);
//添加SearchView的代码开始
MenuItem mMenuItem = menu.findItem(R.id.search);
SearchView mSearchView = (SearchView) mMenuItem.getActionView();
mSearchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
@Override
public boolean onQueryTextSubmit(String query) {
return false;
} @Override
public boolean onQueryTextChange(String newText) {
return false;
}
});
return true;
}
直接运行，没有报错！！！