Unable to create activity instance. ComponentInfo cannot create an instance of a class

Question

Thank you in advance to everyone who looks at this question, especially to those who are trying to answer! This site really helped me!

I am currently experiencing the following error in an Android 4.2.2 application. Below is logcat:

09-09 01:14:27.008: D/dalvikvm(9008): newInstance failed: p0 i0 [0 a1 09-09 01:14:27.008: D/AndroidRuntime(9008): Shutting down VM 09-09 01:14:27.008: W/dalvikvm(9008): threadid=1: thread exiting with uncaught exception (group=0x41173ac8) 09-09 01:14:27.018: E/AndroidRuntime(9008): FATAL EXCEPTION: main 09-09 01:14:27.018: E/AndroidRuntime(9008): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.pocketbotanist/com.pocketbotanist.HomeScreen}: java.lang.InstantiationException: can't instantiate class com.pocketbotanist.HomeScreen 09-09 01:14:27.018: E/AndroidRuntime(9008): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2173) 09-09 01:14:27.018: E/AndroidRuntime(9008): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2297) 09-09 01:14:27.018: E/AndroidRuntime(9008): at android.app.ActivityThread.access$700(ActivityThread.java:152) 09-09 01:14:27.018: E/AndroidRuntime(9008): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1282) 09-09 01:14:27.018: E/AndroidRuntime(9008): at android.os.Handler.dispatchMessage(Handler.java:99) 09-09 01:14:27.018: E/AndroidRuntime(9008): at android.os.Looper.loop(Looper.java:137) 09-09 01:14:27.018: E/AndroidRuntime(9008): at android.app.ActivityThread.main(ActivityThread.java:5328) 09-09 01:14:27.018: E/AndroidRuntime(9008): at java.lang.reflect.Method.invokeNative(Native Method) 09-09 01:14:27.018: E/AndroidRuntime(9008): at java.lang.reflect.Method.invoke(Method.java:511) 09-09 01:14:27.018: E/AndroidRuntime(9008): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102) 09-09 01:14:27.018: E/AndroidRuntime(9008): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869) 09-09 01:14:27.018: E/AndroidRuntime(9008): at dalvik.system.NativeStart.main(Native Method) 09-09 01:14:27.018: E/AndroidRuntime(9008): Caused by: java.lang.InstantiationException: can't instantiate class com.pocketbotanist.HomeScreen 09-09 01:14:27.018: E/AndroidRuntime(9008): at java.lang.Class.newInstanceImpl(Native Method) 09-09 01:14:27.018: E/AndroidRuntime(9008): at java.lang.Class.newInstance(Class.java:1319) 09-09 01:14:27.018: E/AndroidRuntime(9008): at android.app.Instrumentation.newActivity(Instrumentation.java:1071) 09-09 01:14:27.018: E/AndroidRuntime(9008): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2164) 09-09 01:14:27.018: E/AndroidRuntime(9008): ... 11 more 

I tried the project clean, tried to fix the personal Android library that I saw somewhere else, and checked the names of my packages (unless I missed something that I could be!). Here is homescreen.java:

 package com.pocketbotanist; import java.io.File; import android.app.ListActivity; import android.app.LoaderManager; import android.content.Intent; import android.content.Loader; import android.content.pm.ActivityInfo; import android.content.res.Configuration; import android.database.Cursor; import android.net.Uri; import android.os.Bundle; import android.os.Environment; import android.view.ContextMenu; import android.view.ContextMenu.ContextMenuInfo; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.widget.AdapterView.AdapterContextMenuInfo; import android.widget.ArrayAdapter; import android.widget.ListView; import android.widget.SimpleCursorAdapter; import android.widget.Spinner; import com.pocketbotanist.contentprovider.MyEntryContentProvider; import com.pocketbotanist.database.EntryTable; public abstract class HomeScreen extends ListActivity implements LoaderManager.LoaderCallbacks<Cursor> { private static final int DELETE_ID = Menu.FIRST + 1; // private Cursor cursor; private SimpleCursorAdapter adapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_home_screen); this.getListView().setDividerHeight(2); setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT); //Initial folder creation code File appDirectory = new File(Environment.getExternalStorageDirectory().toString()+"/Pocket Botanist/"); if (!appDirectory.exists()){ appDirectory.mkdir(); } //Drop down list code Spinner spinner = (Spinner) findViewById(R.id.action_spinner); ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this, R.array.action_list, android.R.layout.simple_spinner_item); adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); spinner.setAdapter(adapter); fillData(); //View listItem=(View)((Menu) this.getListView()).getItem(0); registerForContextMenu(getListView()); if (adapter.isEmpty()) System.out.println("IT EMPTY"); String[] projection = { EntryTable.COLUMN_CUSTOMID }; long info = adapter.getItemId(0); Uri uri = Uri.parse(MyEntryContentProvider.CONTENT_URI + "/" + info); Cursor cursor = getContentResolver().query(uri, projection, null, null, null); cursor.moveToFirst(); System.out.println((cursor.getString(cursor .getColumnIndexOrThrow(EntryTable.COLUMN_CUSTOMID)))); } @Override public void onConfigurationChanged(Configuration newConfig) { super.onConfigurationChanged(newConfig); setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT); } @Override public boolean onContextItemSelected(MenuItem item) { switch (item.getItemId()) { case DELETE_ID: String[] projection = { EntryTable.COLUMN_PHOTOS }; AdapterContextMenuInfo info = (AdapterContextMenuInfo) item .getMenuInfo(); Uri uri = Uri.parse(MyEntryContentProvider.CONTENT_URI + "/" + info.id); Cursor cursor = getContentResolver().query(uri, projection, null, null, null); cursor.moveToFirst(); File temp = new File(cursor.getString(cursor .getColumnIndexOrThrow(EntryTable.COLUMN_PHOTOS))); if(temp.exists()){ File[] files = temp.listFiles(); for(int i = 0; i < files.length; i++){ files[i].delete(); } temp.delete(); } getContentResolver().delete(uri, null, null); fillData(); return true; } return super.onContextItemSelected(item); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.activity_home_screen, menu); //SearchView searchView = (SearchView) menu.findItem(R.id.menu_search).getActionView(); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { // Handle item selection switch (item.getItemId()) { case R.id.menu_settings: settCall(); return true; case R.id.menu_map: map1_3(); return true; case R.id.menu_edit: entryScreen("New Entry"); return true; default: return super.onOptionsItemSelected(item); } } public void entryScreen(String t){ Intent intent = new Intent(this, EntryScreen.class); intent.putExtra("passer", t); startActivity(intent); } public void settCall(){ Intent sett = new Intent(this,SettingsActivity.class); startActivity(sett); } public void map1_3(){ Intent map13 = new Intent(this,Entrymap_1_3.class); startActivity(map13); } // Opens the second activity if an entry is clicked @Override protected void onListItemClick(ListView l, View v, int position, long id) { super.onListItemClick(l, v, position, id); Intent i = new Intent(this, EntryScreen.class); Uri itemUri = Uri.parse(MyEntryContentProvider.CONTENT_URI + "/" + id); i.putExtra(MyEntryContentProvider.CONTENT_ITEM_TYPE, itemUri); startActivity(i); } //@Override //When we create the loader we're going to get the projection for the ID, customID, species name, and time columns //(insures that these exist within the database) //then we create our cursor loader which will be responsible for loading data from the database //using the projection and our content provider /* public Loader<Cursor> onCreateLoader(int arg0, Bundle arg1) { String[] projection = { EntryTable.COLUMN_ID, EntryTable.COLUMN_CUSTOMID, EntryTable.COLUMN_SPECIES, EntryTable.COLUMN_TIME, EntryTable.COLUMN_PHOTOS, EntryTable.COLUMN_PHOTO }; CursorLoader cursor = new CursorLoader(this, MyEntryContentProvider.CONTENT_URI, projection, null, null, null); if (cursor != null) { ((Cursor) cursor).moveToFirst(); } return cursor; } */ private void fillData() { // Fields from the database (projection) String[] from = new String[] { EntryTable.COLUMN_CUSTOMID, EntryTable.COLUMN_SPECIES , EntryTable.COLUMN_TIME, EntryTable.COLUMN_PHOTO}; // Fields on the UI to which we map int[] to = new int[] { R.id.customidlabel, R.id.namelabel, R.id.timelabel, R.id.imageView }; getLoaderManager().initLoader(1, null, this); //changed to 1 adapter = new SimpleCursorAdapter(this, R.layout.list_row, null, from, to, 0); setListAdapter(adapter); } @Override public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) { super.onCreateContextMenu(menu, v, menuInfo); menu.add(0, DELETE_ID, 0, R.string.menu_delete); } @Override public void onLoadFinished(Loader<Cursor> arg0, Cursor data) { adapter.swapCursor(data); } @Override public void onLoaderReset(Loader<Cursor> arg0) { adapter.swapCursor(null); } } 

I understand that the problem may be here, so here is my AndroidManifest.xml file:

 <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.pocketbotanist" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="11" android:targetSdkVersion="18" /> <uses-permission android:name="android.permission.INTERNET" /> <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> <uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" /> <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" /> <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> <uses-feature android:glEsVersion="0x00020000" android:required="true"/> <permission android:name="com.pocketbotanist.permission.MAPS_RECEIVE" android:protectionLevel="signature"/> <uses-permission android:name="com.pocketbotanist.permission.MAPS_RECEIVE"/> <application android:allowBackup="true" android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" android:configChanges="keyboardHidden|orientation" > <activity android:name="com.pocketbotanist.HomeScreen" android:label="@string/main" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <activity android:name="com.pocketbotanist.EntryScreen" android:label="@string/title_activity_entry_screen" android:windowSoftInputMode="stateHidden" > </activity> <activity android:name="com.pocketbotanist.SettingsActivity" android:label="@string/title_activity_settings" > </activity> <activity android:name="com.pocketbotanist.ManualLocationActivity" android:label="@string/title_activity_manual_location" > </activity> <activity android:name="com.pocketbotanist.Entrymap_1_3" android:label="@string/title_activity_entrymap_1_3" > </activity> <activity android:name="com.pocketbotanist.Location_2_3" android:label="@string/title_location_2_3" > </activity> <activity android:name="com.pocketbotanist.Mapfragmentpreview" android:configChanges="orientation|keyboardHidden|screenSize" android:label="@string/title_activity_mapfragmentpreview" android:theme="@style/FullscreenTheme" > </activity> <meta-data android:name="com.google.android.maps.v2.API_KEY" android:value="(removing key for security reasons)" /> <uses-library android:name="com.google.android.maps" android:required="true" /> <provider android:name="com.pocketbotanist.contentprovider.MyEntryContentProvider" android:authorities="com.pocketbotanist.contentprovider" android:exported="false"> </provider> </application> </manifest> 

Does anyone have any ideas / suggestions? Thanks again!

Answer 1

Abstract classes are by definition not real.

change

 public abstract class HomeScreen extends ListActivity 

to

 public class HomeScreen extends ListActivity 

Answer 2

Your class is abstract classes.

Abstract classes are by definition not real.

Answer 3

private class does not work:

Replace below code, the open abstract class HomeScreen extends ListActivity implements LoaderManager.LoaderCallbacks

in

Public class HomeScreen extends ListActivity implements LoaderManager.LoaderCallbacks

He will work.