我在尝试阅读Nexus 5（更新为棒棒糖）中的手机联系时遇到以下错误。
java.lang.NullPointerException: Attempt to invoke interface method 'boolean android.database.Cursor.moveToNext()' on a null object reference
at mycomp.android.ui.fragments.DirectoriesFragment.readContacts(SourceFile:595)
at mycomp.android.ui.fragments.DirectoriesFragment.processOneDirectory(SourceFile:744)
at mycomp.android.ui.fragments.DirectoriesFragment.onLoadFinished(SourceFile:722)
at mycomp.android.utils.RESTLoaderFragment.onLoadFinished(SourceFile:1)
at android.app.LoaderManagerImpl$LoaderInfo.callOnLoadFinished(LoaderManager.java:483)
at android.app.LoaderManagerImpl$LoaderInfo.onLoadComplete(LoaderManager.java:451)
at android.content.Loader.deliverResult(Loader.java:144)
at mycomp.android.utils.loader.RESTLoader.deliverResult(SourceFile:322)
at mycomp.android.utils.loader.RESTLoader.deliverResult(SourceFile:1)
at android.content.AsyncTaskLoader.dispatchOnLoadComplete(AsyncTaskLoader.java:265)
at android.content.AsyncTaskLoader$LoadTask.onPostExecute(AsyncTaskLoader.java:92)
at android.os.AsyncTask.finish(AsyncTask.java:632)
at android.os.AsyncTask.access$600(AsyncTask.java:177)
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
at android.os.Handler.dispatchMessage(Handler.java:102)
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)
我正在使用以下代码从手机中检索联系人
private void readContacts() {
ContentResolver cr = getActivity().getContentResolver();
Cursor cur = cr.query(ContactsContract.Contacts.CONTENT_URI, null,
null, null, null);
Cursor c = null ;
Cursor pCur = null;
try {
String phone = null;
if (cur.getCount() > 0) {
while (cur.moveToNext()) {
try {
DirectoryRecordEntry entry = null;
String id = cur.getString(cur
.getColumnIndex(ContactsContract.Contacts._ID));
String name = cur
.getString(cur
.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME));
int idIndex = cur.getColumnIndexOrThrow(Contacts._ID);
long ids = cur.getLong(idIndex);
Uri rawContactUri = ContentUris.withAppendedId(
RawContacts.CONTENT_URI, ids);
Uri entityUri = Uri.withAppendedPath(rawContactUri,
Entity.CONTENT_DIRECTORY);
c= getActivity().getContentResolver().query(entityUri,
new String[]{
RawContacts.SOURCE_ID}, null, null, null);
String source_id = "";
//在这里得到空指针异常，c为null：（
while (c.moveToNext()) {
source_id = c.getString(0);
}
if (Integer
.parseInt(cur.getString(cur
.getColumnIndex(ContactsContract.Contacts.HAS_PHONE_NUMBER))) > 0) {
if (source_id != null && source_id.length()>0) {
entry = new OutlookContactEntry(name, "");
} else {
entry = new PhoneNumberEntry(name, "");
}
pCur = cr.query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
null,
ContactsContract.CommonDataKinds.Phone.CONTACT_ID
+ " = ?", new String[]{id},
null);
while (pCur.moveToNext()) {
try {
phone = pCur
.getString(pCur
.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));
int phoneType = pCur
.getInt(pCur
.getColumnIndex(ContactsContract.CommonDataKinds.Phone.TYPE));
if (entry instanceof OutlookContactEntry) {
OutlookContactEntry oEntry = (OutlookContactEntry) entry;
oEntry.addContact(getType(phoneType), phone);
} else {
entry.getPhNumberList().add(phone);
}
} catch (Exception e) {
Log.e(CLASS_NAME, "Error in retrieving contacts from phone",e);
}
}
}
if (entry != null) {
if (entry instanceof OutlookContactEntry) {
OutlookContactEntry oEntry = (OutlookContactEntry) entry;
List<String> list =new ArrayList<String>(oEntry.getContacts().values());
if(!list.isEmpty()){
entry.setNumber(list.get(0));
}
}else{
if(!entry.getPhNumberList().isEmpty()){
entry.setNumber(entry.getPhNumberList().get(0));
}
}
objListRowRecord.put(name, entry);
}
} catch (Exception e) {
Log.e(CLASS_NAME, "Error in retrieving contacts from phone",e);
}
}
}
} catch (Exception e) {
Log.e(CLASS_NAME, "Error in retrieving contacts from phone",e);
}finally
{
try {
if(pCur!=null){
pCur.close();
}
if(c!=null){
c.close();
}
if(cur!=null){
cur.close();
}
cr=null;
} catch (Exception e) {
Log.e(CLASS_NAME, "Error closing cursor",e);
}
}
}
我在将kitkat更新为棒棒糖后才遇到此问题
可以通过空检查来解决，但我真的想知道背后的原因。
任何帮助将不胜感激
由于
Amith
答案 0 :(得分：2)
documentation of ContentResolver.query()说：
<强>返回
Cursor对象，位于第一个条目之前，或者为null
返回null因为允许这样做。
查询内容解析器时，您始终需要进行null检查。
答案 1 :(得分：1)
/**
* This method is to read contacts.
*/
public void readContacts() {
localPhTempList.clear();
ContentResolver cr = activity.getContentResolver();
Cursor cur = cr.query(ContactsContract.Contacts.CONTENT_URI, null, null, null, null);
String phone = null;
Cursor c = null;
Cursor pCur = null;
try {
if (cur != null && cur.getCount() > 0) {
while (cur.moveToNext()) {
try {
DirectoryRecordEntry entry = null;
String id = cur.getString(cur.getColumnIndex(ContactsContract.Contacts._ID));
String name = cur.getString(cur.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME));
int idIndex = cur.getColumnIndexOrThrow(Contacts._ID);
long ids = cur.getLong(idIndex);
Uri rawContactUri = ContentUris.withAppendedId(RawContacts.CONTENT_URI, ids);
Uri entityUri = Uri.withAppendedPath(rawContactUri, Entity.CONTENT_DIRECTORY);
c = activity.getContentResolver().query(entityUri, new String[] {
RawContacts.SOURCE_ID }, null, null, null);
String source_id = "";
if (c != null) {
while (c.moveToNext()) {
source_id = c.getString(0);
}
}
if (c != null) {
c.close();
}
if (Integer.parseInt(cur.getString(cur.getColumnIndex(ContactsContract.Contacts.HAS_PHONE_NUMBER))) > 0) {
if (source_id != null && source_id.length() > 0) {
entry = new OutlookContactEntry(name, "-1");
} else {
entry = new PhoneNumberEntry(name, "-2");
}
pCur = cr.query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, ContactsContract.CommonDataKinds.Phone.CONTACT_ID + " ='"
+ id + "'", null, null);
if (pCur != null) {
while (pCur.moveToNext()) {
try {
phone = pCur.getString(pCur.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));
int phoneType = pCur.getInt(pCur.getColumnIndex(ContactsContract.CommonDataKinds.Phone.TYPE));
if (entry instanceof OutlookContactEntry) {
OutlookContactEntry oEntry = (OutlookContactEntry) entry;
String names = getType(phoneType);
String number = phone;
if (names != null && names.length() > 0 && number != null && number.length() > 0
/*
* && !number.equalsIgnoreCase("-1")
* && !number.equalsIgnoreCase("-1")
*/) {
oEntry.addContact(names, number);
}
} else {
entry.getPhNumberList().add(phone);
}
} catch (Exception e) {
Log.e(CLASS_NAME, "Error in retrieving contacts from phone", e);
}
}
if (pCur != null) {
pCur.close();
}
}
}
if (entry != null) {
if (entry instanceof OutlookContactEntry) {
OutlookContactEntry oEntry = (OutlookContactEntry) entry;
List<String> list = new ArrayList<String>(oEntry.getContacts().values());
if (!list.isEmpty()) {
entry.setNumber(list.get(0));
}
} else {
if (!entry.getPhNumberList().isEmpty()) {
entry.setNumber(entry.getPhNumberList().get(0));
}
}
// objListRowRecord.put(name, entry);
if (!(entry.getNumber().equalsIgnoreCase("-1") || entry.getNumber().equalsIgnoreCase("-2"))) {
localPhTempList.add(entry);
}
}
} catch (Exception e) {
Log.e(CLASS_NAME, "Error in retrieving contacts from phone", e);
}
}
}
} catch (Exception e) {
Log.e(CLASS_NAME, "Error in retrieving contacts from phone", e);
} finally {
try {
if (pCur != null) {
pCur.close();
pCur = null;
}
if (c != null) {
c.close();
c = null;
}
if (cur != null) {
cur.close();
cur = null;
}
cr = null;
} catch (Exception e) {
Log.e(CLASS_NAME, "Error closing cursor", e);
}
}
}
答案 2 :(得分：0)
Always do a
Cursor cursor = query();//Your Custom Query Method
if(cursor != null){
//Iterate
for(cursor.moveToFirst();!cursor.isAfterLast();cursor.moveToNext()){
//Get cursor values
}
if(!cursor.isClosed()){cursor.close();}
}