错误:在显示java.lang.NullPointerException android.support.v4.content.Loader [英] Error: java.lang.NullPointerException at android.support.v4.content.Loader
问题描述
我想实施 LoaderManager
在我的应用程序,以减少启动时间的正如你可以看到这里但在该线程执行的建议,我是收到以下错误 initLoader(INT,捆绑后, LoaderManager.LoaderCallbacks)在类型LoaderManager不适用于参数(INT,空,MainActivity)
。在这里搜索后,我发现对于第二个错误解决这里。但是从实施后的建议后,现在我得到的错误显示java.lang.NullPointerException
。我把了code,我现在有,谁能告诉我,我怎么能解决这个问题。
在android.support.v4.content.Loader
FULL code可以看出 这里
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20 10-03:11:34.849:E / AndroidRuntime(2968):了java.lang.RuntimeException:无法启动活动ComponentInfo {com.test.sms.it/com。 test.sms.it.MainActivity}:显示java.lang.NullPointerException
10-03 20:11:34.849:E / AndroidRuntime(2968):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
10-03 20:11:34.849:E / AndroidRuntime(2968):在android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
10-03 20:11:34.849:E / AndroidRuntime(2968):在android.app.ActivityThread.access $ 1500(ActivityThread.java:117)
10-03 20:11:34.849:E / AndroidRuntime(2968):在android.app.ActivityThread $ H.handleMessage(ActivityThread.java:931)
10-03 20:11:34.849:E / AndroidRuntime(2968):在android.os.Handler.dispatchMessage(Handler.java:99)
10-03 20:11:34.849:E / AndroidRuntime(2968):在android.os.Looper.loop(Looper.java:123)
10-03 20:11:34.849:E / AndroidRuntime(2968):在android.app.ActivityThread.main(ActivityThread.java:3683)
10-03 20:11:34.849:E / AndroidRuntime(2968):在java.lang.reflect.Method.invokeNative(本机方法)
10-03 20:11:34.849:E / AndroidRuntime(2968):在java.lang.reflect.Method.invoke(Method.java:507)
10-03 20:11:34.849:E / AndroidRuntime(2968):在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:839)
10-03 20:11:34.849:E / AndroidRuntime(2968):在com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
10-03 20:11:34.849:E / AndroidRuntime(2968):在dalvik.system.NativeStart.main(本机方法)
10-03 20:11:34.849:E / AndroidRuntime(2968):因:显示java.lang.NullPointerException
10-03 20:11:34.849:E / AndroidRuntime(2968):在android.support.v4.content.Loader<&初始化GT;(Loader.java:91)
10-03 20:11:34.849:E / AndroidRuntime(2968):在android.support.v4.content.AsyncTaskLoader<&初始化GT;(AsyncTaskLoader.java:92)
10-03 20:11:34.849:E / AndroidRuntime(2968):在com.test.sms.it.MainActivity $ ContactsDataLoader<&初始化GT;(MainActivity.java:104)
10-03 20:11:34.849:E / AndroidRuntime(2968):在com.test.sms.it.MainActivity.onCreateLoader(MainActivity.java:496)
10-03 20:11:34.849:E / AndroidRuntime(2968):在android.support.v4.app.LoaderManagerImpl.createLoader(LoaderManager.java:487)
10-03 20:11:34.849:E / AndroidRuntime(2968):在android.support.v4.app.LoaderManagerImpl.createAndInstallLoader(LoaderManager.java:496)
10-03 20:11:34.849:E / AndroidRuntime(2968):在android.support.v4.app.LoaderManagerImpl.initLoader(LoaderManager.java:550)
10-03 20:11:34.849:E / AndroidRuntime(2968):在com.test.sms.it.MainActivity.onCreate(MainActivity.java:91)
10-03 20:11:34.849:E / AndroidRuntime(2968):在android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
10-03 20:11:34.849:E / AndroidRuntime(2968):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
MainActivity.java
进口的java.util.ArrayList;
进口的java.util.HashMap;
进口的java.util.Map;
进口android.app.AlertDialog;
进口android.app.ProgressDialog;
进口android.content.Context;
进口android.content.DialogInterface;
进口android.content.Intent;
进口android.content.Shared preferences;
进口android.database.Cursor;
进口android.graphics.Color;
进口android.net.ConnectivityManager;
进口android.net.NetworkInfo;
进口android.net.Uri;
进口android.os.AsyncTask;
进口android.os.Bundle;
。进口的Android preference preferenceManager。
进口android.provider.ContactsContract;
进口android.support.v4.app.FragmentActivity;
进口android.support.v4.app.LoaderManager;
进口android.support.v4.content.AsyncTaskLoader;
进口android.support.v4.content.Loader;
进口android.view.KeyEvent;
进口android.view.Menu;
进口android.view.View;
进口android.view.View.OnClickListener;
进口android.view.Window;
进口android.widget.AdapterView;
进口android.widget.AdapterView.OnItemClickListener;
进口android.widget.AutoCompleteTextView;
进口android.widget.Button;
进口android.widget.EditText;
进口android.widget.SimpleAdapter;
进口android.widget.Spinner;
进口android.widget.Toast;
@覆盖
公共无效的onCreate(捆绑savedInstanceState){
super.onCreate(savedInstanceState);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
的setContentView(R.layout.activity_main);
editUser1UserName =(EditText上)findViewById(R.id.editTextUser1UserName);
editUser1Password =(EditText上)findViewById(R.id.editTextUser1Password);
editUser2UserName =(EditText上)findViewById(R.id.editTextUser2UserName);
editUser2Password =(EditText上)findViewById(R.id.editTextUser2Password);
editUser3UserName =(EditText上)findViewById(R.id.editTextUser3UserName);
editUser3Password =(EditText上)findViewById(R.id.editTextUser3Password);
editUser4UserName =(EditText上)findViewById(R.id.editTextUser4UserName);
editUser4Password =(EditText上)findViewById(R.id.editTextUser4Password);
editUser5UserName =(EditText上)findViewById(R.id.editTextUser5UserName);
editUser5Password =(EditText上)findViewById(R.id.editTextUser5Password);
mTxtPhoneNo =(AutoCompleteTextView)findViewById(R.id.mmWhoNo);
mTxtPhoneNo.setThreshold(1);
mTxtPhoneNo.setTextColor(Color.BLACK);
EDITTEXT =(EditText上)findViewById(R.id.editTextMessage);
spinner1 =(微调)findViewById(R.id.spinnerGateway);
btnsend =(按钮)findViewById(R.id.btnSend);
btnContact =(按钮)findViewById(R.id.btnContact);
btnClear =(按钮)findViewById(R.id.btnClear);
btnClear.setOnClickListener(本);
btnsend.setOnClickListener(本);
btnContact.setOnClickListener(本);
mPeopleList =新的ArrayList<地图<字符串,字符串>>();
getSupportLoaderManager()initLoader(0,null,则此)。
mTxtPhoneNo.setOnItemClickListener(本);
readPerson();
面板面板;
topPanel = =面板(面板)findViewById(R.id.mytopPanel);
panel.setOnPanelListener(本);
panel.setInterpolator(新BounceInterpolator(Type.OUT));
getLoginDetails();
}公共类ContactsDataLoader扩展
AsyncTaskLoader< ArrayList的<地图<字符串,字符串>>> {
公共ContactsDataLoader(上下文的背景下){
超级(上下文);
} @覆盖
公众的ArrayList<地图<字符串,字符串>> loadInBackground(){
mPeopleList.clear();
光标人= getContentResolver()查询(
ContactsContract.Contacts.CONTENT_URI,NULL,NULL,NULL,
空值);
而(people.moveToNext()){
字符串CONTACTNAME =人
.getString(人
.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME));
字符串的ContactID = people.getString(人
.getColumnIndex(ContactsContract.Contacts._ID));
字符串hasPhone =人
.getString(人
.getColumnIndex(ContactsContract.Contacts.HAS_PHONE_NUMBER)); 如果((的Integer.parseInt(hasPhone)0)){
光标手机= getContentResolver()查询(
ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
空值,
ContactsContract.CommonDataKinds.Phone.CONTACT_ID
+=+的ContactID,NULL,NULL);
而(phones.moveToNext()){
字符串phoneNumber的=手机
.getString(电话
.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));
字符串numberType =手机
.getString(电话
.getColumnIndex(ContactsContract.CommonDataKinds.Phone.TYPE));
地图<字符串,字符串> NamePhoneType =新的HashMap<字符串,字符串>();
NamePhoneType.put(名,联系人姓名);
NamePhoneType.put(手机,phoneNumber的);
如果(numberType.equals(0))
NamePhoneType.put(类型,工作);
否则如果(numberType.equals(1))
NamePhoneType.put(类型,家);
否则如果(numberType.equals(2))
NamePhoneType.put(类型,手机);
其他
NamePhoneType.put(类型,其他);
mPeopleList.add(NamePhoneType);
}
phones.close();
}
}
people.close();
startManagingCursor(人);
返回mPeopleList;
} @覆盖
保护无效onStartLoading(){
super.onStartLoading();
的forceload();
}
}公共装载机< ArrayList的<地图<字符串,字符串>>> onCreateLoader(INT ID,
捆绑参数){
返回新ContactsDataLoader(背景);
}公共无效onLoadFinished(装载机< ArrayList的<地图<字符串,字符串>>>装载机,
ArrayList的<地图<字符串,字符串>>数据){
mPeopleList =数据;
mAdapter =新SimpleAdapter(这一点,mPeopleList,R.layout.custcontview,
新的String [] {姓名,手机,类型},新的INT [] {
R.id.ccontName,R.id.ccontNo,R.id.ccontType});
mTxtPhoneNo.setAdapter(mAdapter);
}公共无效onLoaderReset(装载机< ArrayList的<地图<字符串,字符串>>>装载机){
mPeopleList =新的ArrayList<地图<字符串,字符串>>();
mAdapter =新SimpleAdapter(这一点,mPeopleList,R.layout.custcontview,
新的String [] {姓名,手机,类型},新的INT [] {
R.id.ccontName,R.id.ccontNo,R.id.ccontType});
mTxtPhoneNo.setAdapter(mAdapter);
}
RC
的评论是你的问题的答案。你传递一个空
上下文
(因为我没有看到任何地方code您发布的背景
可变正与一个有效的参考初始化)到您的自定义加载程序和code将无法用 NullPointerException异常
。如果你从我的previous答案用我的code,那么这些回调在活动
实施。在这种情况下,只是通过这个
,提到当前的活动
例如,您的自定义加载器:
公共装载机< ArrayList的<地图<字符串,字符串>>> onCreateLoader(INT ID,
捆绑参数){
返回新ContactsDataLoader(本);
}
另外,如果你关闭游标,就没有必要使用 startManagingCursor()
为光标
作为你可能会惹上麻烦。
I want to implement LoaderManager
in my application in order to reduce the startup time As you can see here but after implementing the suggestion in that thread i was getting the following error initLoader(int, Bundle, LoaderManager.LoaderCallbacks) in the type LoaderManager is not applicable for the arguments (int, null, MainActivity)
. After searching on here i found the solution for that second error here. But after implementing the suggestion from later, now i am getting the error java.lang.NullPointerException
at android.support.v4.content.Loader
. I am putting up the code which i currently have, can anyone tell me, how can i solve this problem
FULL CODE CAN BE SEEN HERE
Log Cat
10-03 20:11:34.849: E/AndroidRuntime(2968): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.test.sms.it/com.test.sms.it.MainActivity}: java.lang.NullPointerException
10-03 20:11:34.849: E/AndroidRuntime(2968): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
10-03 20:11:34.849: E/AndroidRuntime(2968): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
10-03 20:11:34.849: E/AndroidRuntime(2968): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
10-03 20:11:34.849: E/AndroidRuntime(2968): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
10-03 20:11:34.849: E/AndroidRuntime(2968): at android.os.Handler.dispatchMessage(Handler.java:99)
10-03 20:11:34.849: E/AndroidRuntime(2968): at android.os.Looper.loop(Looper.java:123)
10-03 20:11:34.849: E/AndroidRuntime(2968): at android.app.ActivityThread.main(ActivityThread.java:3683)
10-03 20:11:34.849: E/AndroidRuntime(2968): at java.lang.reflect.Method.invokeNative(Native Method)
10-03 20:11:34.849: E/AndroidRuntime(2968): at java.lang.reflect.Method.invoke(Method.java:507)
10-03 20:11:34.849: E/AndroidRuntime(2968): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
10-03 20:11:34.849: E/AndroidRuntime(2968): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
10-03 20:11:34.849: E/AndroidRuntime(2968): at dalvik.system.NativeStart.main(Native Method)
10-03 20:11:34.849: E/AndroidRuntime(2968): Caused by: java.lang.NullPointerException
10-03 20:11:34.849: E/AndroidRuntime(2968): at android.support.v4.content.Loader.<init>(Loader.java:91)
10-03 20:11:34.849: E/AndroidRuntime(2968): at android.support.v4.content.AsyncTaskLoader.<init>(AsyncTaskLoader.java:92)
10-03 20:11:34.849: E/AndroidRuntime(2968): at com.test.sms.it.MainActivity$ContactsDataLoader.<init>(MainActivity.java:104)
10-03 20:11:34.849: E/AndroidRuntime(2968): at com.test.sms.it.MainActivity.onCreateLoader(MainActivity.java:496)
10-03 20:11:34.849: E/AndroidRuntime(2968): at android.support.v4.app.LoaderManagerImpl.createLoader(LoaderManager.java:487)
10-03 20:11:34.849: E/AndroidRuntime(2968): at android.support.v4.app.LoaderManagerImpl.createAndInstallLoader(LoaderManager.java:496)
10-03 20:11:34.849: E/AndroidRuntime(2968): at android.support.v4.app.LoaderManagerImpl.initLoader(LoaderManager.java:550)
10-03 20:11:34.849: E/AndroidRuntime(2968): at com.test.sms.it.MainActivity.onCreate(MainActivity.java:91)
10-03 20:11:34.849: E/AndroidRuntime(2968): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
10-03 20:11:34.849: E/AndroidRuntime(2968): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
MainActivity.java
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.SharedPreferences;
import android.database.Cursor;
import android.graphics.Color;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.provider.ContactsContract;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.LoaderManager;
import android.support.v4.content.AsyncTaskLoader;
import android.support.v4.content.Loader;
import android.view.KeyEvent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.Window;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AutoCompleteTextView;
import android.widget.Button;
import android.widget.EditText;
import android.widget.SimpleAdapter;
import android.widget.Spinner;
import android.widget.Toast;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.activity_main);
editUser1UserName = (EditText) findViewById(R.id.editTextUser1UserName);
editUser1Password = (EditText) findViewById(R.id.editTextUser1Password);
editUser2UserName = (EditText) findViewById(R.id.editTextUser2UserName);
editUser2Password = (EditText) findViewById(R.id.editTextUser2Password);
editUser3UserName = (EditText) findViewById(R.id.editTextUser3UserName);
editUser3Password = (EditText) findViewById(R.id.editTextUser3Password);
editUser4UserName = (EditText) findViewById(R.id.editTextUser4UserName);
editUser4Password = (EditText) findViewById(R.id.editTextUser4Password);
editUser5UserName = (EditText) findViewById(R.id.editTextUser5UserName);
editUser5Password = (EditText) findViewById(R.id.editTextUser5Password);
mTxtPhoneNo = (AutoCompleteTextView) findViewById(R.id.mmWhoNo);
mTxtPhoneNo.setThreshold(1);
mTxtPhoneNo.setTextColor(Color.BLACK);
editText = (EditText) findViewById(R.id.editTextMessage);
spinner1 = (Spinner) findViewById(R.id.spinnerGateway);
btnsend = (Button) findViewById(R.id.btnSend);
btnContact = (Button) findViewById(R.id.btnContact);
btnClear = (Button) findViewById(R.id.btnClear);
btnClear.setOnClickListener(this);
btnsend.setOnClickListener(this);
btnContact.setOnClickListener(this);
mPeopleList = new ArrayList<Map<String, String>>();
getSupportLoaderManager().initLoader(0, null, this);
mTxtPhoneNo.setOnItemClickListener(this);
readPerson();
Panel panel;
topPanel = panel = (Panel) findViewById(R.id.mytopPanel);
panel.setOnPanelListener(this);
panel.setInterpolator(new BounceInterpolator(Type.OUT));
getLoginDetails();
}
public class ContactsDataLoader extends
AsyncTaskLoader<ArrayList<Map<String, String>>> {
public ContactsDataLoader(Context context) {
super(context);
}
@Override
public ArrayList<Map<String, String>> loadInBackground() {
mPeopleList.clear();
Cursor people = getContentResolver().query(
ContactsContract.Contacts.CONTENT_URI, null, null, null,
null);
while (people.moveToNext()) {
String contactName = people
.getString(people
.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME));
String contactId = people.getString(people
.getColumnIndex(ContactsContract.Contacts._ID));
String hasPhone = people
.getString(people
.getColumnIndex(ContactsContract.Contacts.HAS_PHONE_NUMBER));
if ((Integer.parseInt(hasPhone) > 0)) {
Cursor phones = getContentResolver().query(
ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
null,
ContactsContract.CommonDataKinds.Phone.CONTACT_ID
+ " = " + contactId, null, null);
while (phones.moveToNext()) {
String phoneNumber = phones
.getString(phones
.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));
String numberType = phones
.getString(phones
.getColumnIndex(ContactsContract.CommonDataKinds.Phone.TYPE));
Map<String, String> NamePhoneType = new HashMap<String, String>();
NamePhoneType.put("Name", contactName);
NamePhoneType.put("Phone", phoneNumber);
if (numberType.equals("0"))
NamePhoneType.put("Type", "Work");
else if (numberType.equals("1"))
NamePhoneType.put("Type", "Home");
else if (numberType.equals("2"))
NamePhoneType.put("Type", "Mobile");
else
NamePhoneType.put("Type", "Other");
mPeopleList.add(NamePhoneType);
}
phones.close();
}
}
people.close();
startManagingCursor(people);
return mPeopleList;
}
@Override
protected void onStartLoading() {
super.onStartLoading();
forceLoad();
}
}
public Loader<ArrayList<Map<String, String>>> onCreateLoader(int id,
Bundle args) {
return new ContactsDataLoader(context);
}
public void onLoadFinished(Loader<ArrayList<Map<String, String>>> loader,
ArrayList<Map<String, String>> data) {
mPeopleList = data;
mAdapter = new SimpleAdapter(this, mPeopleList, R.layout.custcontview,
new String[] { "Name", "Phone", "Type" }, new int[] {
R.id.ccontName, R.id.ccontNo, R.id.ccontType });
mTxtPhoneNo.setAdapter(mAdapter);
}
public void onLoaderReset(Loader<ArrayList<Map<String, String>>> loader) {
mPeopleList = new ArrayList<Map<String, String>>();
mAdapter = new SimpleAdapter(this, mPeopleList, R.layout.custcontview,
new String[] { "Name", "Phone", "Type" }, new int[] {
R.id.ccontName, R.id.ccontNo, R.id.ccontType });
mTxtPhoneNo.setAdapter(mAdapter);
}
RC
's comment is the answer of your problem. You pass a null
Context
(as I don't see anywhere in the code you posted the context
variable being initialized with a valid reference) to your custom loader and the code will fail with a NullPointerException
. If you used my code from my previous answer then those callbacks are implemented in your Activity
. In this case just pass this
, the reference to your current Activity
instance, to your custom loader:
public Loader<ArrayList<Map<String, String>>> onCreateLoader(int id,
Bundle args) {
return new ContactsDataLoader(this);
}
Also, if you close the cursor, there is no need to use startManagingCursor()
for that Cursor
as you might get in trouble.
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