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Я пытаюсь использовать Intent для запуска ArrAdapter.java из класса FileEvent.java. В startActivity(), я получаю исключение из null-указателя. FileEvent.java расширяет действие, но не имеет setContentView(). Потому что я не показываю ничего в UI в этом классе. Пожалуйста, смотрите следующий код -Получение NullPointerException при запуске Activity in android
FileEvent.java: -
public class FileEvent extends Activity implements ObserverActivity{
public static final String PREFS_NAME = "MyPreferencesFile";
public static String path2;
public String filename;
public String path;
MyFileObserver myFileObserver;
public adapter info ;
public ArrayAdapter<String> adapterarr;
ListView listView;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
this.info = new adapter(this);
myFileObserver = new MyFileObserver("/storage/sdcard/DCIM/SAMPLE_IMAGES/");
myFileObserver.registerObserver(this);
myFileObserver.startWatching();
Bundle bundle = getIntent().getExtras();
}
protected void onPause(){
myFileObserver.stopWatching();
myFileObserver.unregisterObserver(this);
}
protected void onResume(){
myFileObserver.registerObserver(this);
myFileObserver.startWatching();
}
public void insert(String path) {
// TODO Auto-generated method stub
// try{
this.info = new adapter(this);
this.filename = path;
if(info == null)
{
System.out.println("info is null here.");
}
else
{
System.out.println("info is not null here.");
// setpath(path);
System.out.println("sharedpreferences "+FileEvent.path2);
startActivity(new Intent("android.intent.action.ArrAdapter")); //Here I am getting the NullPointerException.
// i.putExtra("path", path);
/* }
}
private void setpath(String path) {
// TODO Auto-generated method stub
FileEvent.path2 = path;
}
public void delete(String path) {
Log.v("entered delete() in FileEvent", "entered delete() in FileEvent");
// TODO Auto-generated method stub
this.info = new adapter(this);
try{
if(this.info == null)
{
System.out.println("this.info is null here");
}
else
{
System.out.println("this.info is not null here");
int id_of_deleted_person_photo = info.deletefile(path);
Log.v("_id of FileName to delete : ", ""+id_of_deleted_person_photo+"");
}
}
catch(Exception e)
{
Log.v("Error in delete() in FileEvent.java : ",e.toString());
}
Log.v("completed delete() in FileEvent", "completed delete() in FileEvent");
}
@Override
public void onFileObserved(int Event, String path) {
// TODO Auto-generated method stub
Log.v("path in onFileObserved",path);
}
ArrAdapter.java: -
public class ArrAdapter extends ListActivity{
public String path;
ListView listView;
public adapter info;
public static final String PREFS_NAME = "MyPreferencesFile";
private ArrayAdapter<String> adapterarr;
private String filename;
public Context context;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.fileeventlist);
info = new adapter(this);
listView = (ListView) findViewById(android.R.id.list);
Log.v("value of FileEvent.path2 : ",FileEvent.path2);
insert(FileEvent.path2);
}
private void insert(String var_from_prev_intent1) {
// TODO Auto-generated method stub
try{
int rowcount = info.getrowcountofpersons();
Log.v("rowcount in new list onCreate: ",
""+info.getrowcountofpersons()+"");
String[] values = new String[rowcount];
for(int i =1;i<=rowcount;i++)
{
values[i-1]=info.getPersonList(i);
System.out.println("in for loop now"+values[i-1]);
}
this.adapterarr = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, values);
}
catch(Exception e)
{
Log.v("Error at ArrayAdapter : ",e.toString());
}
if(adapterarr == null)
{
System.out.println("2. Here adapterarr is null.");
}
else
{
System.out.println("2. Here adapterarr is not null.");
}
listView.setItemsCanFocus(false);
listView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
// Assign adapter to List
setListAdapter(adapterarr);
// new Bullet(info).execute((Void)null);
}
protected void onListItemClick(ListView l, View v, int position, long id) {
// try{
super.onListItemClick(l, v, position, id);
// ListView Clicked item index
int itemPosition = position;
// ListView Clicked item value
String itemValue = (String) l.getItemAtPosition(position);
// content.setText("Click : \n Position :"+itemPosition+" \n ListItem : " +itemValue);
String personname = itemValue;
try
{
System.out.println("paths in FileEvent : "+filename);
info.insert(filename,personname);
}
catch(Exception e)
{
e.printStackTrace();
}
/* }
catch (Exception e)
{
Log.v("Error in insert() definition FileEvent.java : ",e.toString());
}
*/
} }
}
я получаю LogCat следующим образом -
09-28 00:04:40.537: A/FileObserver(31484): Unhandled exception in FileObserver [email protected]
09-28 00:04:40.537: A/FileObserver(31484): java.lang.NullPointerException
09-28 00:04:40.537: A/FileObserver(31484): at android.app.Activity.startActivityForResult(Activity.java:3390)
09-28 00:04:40.537: A/FileObserver(31484): at android.app.Activity.startActivityForResult(Activity.java:3351)
09-28 00:04:40.537: A/FileObserver(31484): at android.app.Activity.startActivity(Activity.java:3587)
09-28 00:04:40.537: A/FileObserver(31484): at android.app.Activity.startActivity(Activity.java:3555)
09-28 00:04:40.537: A/FileObserver(31484): at com.example.sample_fileobserver.FileEvent.insert(FileEvent.java:95)
09-28 00:04:40.537: A/FileObserver(31484): at com.example.sample_fileobserver.MyFileObserver.onEvent(MyFileObserver.java:59)
09-28 00:04:40.537: A/FileObserver(31484): at android.os.FileObserver$ObserverThread.onEvent(FileObserver.java:125)
09-28 00:04:40.537: A/FileObserver(31484): at android.os.FileObserver$ObserverThread.observe(Native Method)
09-28 00:04:40.537: A/FileObserver(31484): at android.os.FileObserver$ObserverThread.run(FileObserver.java:88)
AndroidManifest. xml: -
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.sample_fileobserver"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.sample_fileobserver.FileEvent"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.FIleEvent" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
<activity
android:name="com.example.sample_fileobserver.ArrAdapter"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.ArrAdapter" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
<activity
android:name="com.example.sample_fileobserver.FileModificationMonitor"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service
android:enabled="true"
android:name="com.example.sample_fileobserver.FileModificationService">
</service>
</application>
Я зарегистрировал оба класса в файле манифеста. Если нет, возможно, у меня есть ClassNotFound Exception. Таким образом, я не могу понять, почему это исключение при поднятии.
Заранее спасибо.
ли вы пытались с startActivity (новый Intent (FileEvent.this, ArrAdapter.class))? –
Да, я пробовал, уже @Hardy – nki
Можете ли вы вставить свой AndroidManifest.xml код? –