Je suis tout nouveau à développer pour Android et ont frappé quelque chose d'une pierre d'achoppement que je ne peux pas sembler contourner. En utilisant l'exemple du bloc-notes, j'ai créé mon propre ContentProvider pour fournir des données à partir d'une base de données que j'hébergerai éventuellement sur un serveur Web. Mais c'est loin d'où je suis en ce moment.ContentProvider échoue sur l'insertion
Le simple fait de tester mon ContentProvider m'a causé un mal de tête que je n'arrive pas à résoudre. Pour une raison quelconque, lorsque le fournisseur appelle SQLiteDatabase db = mOpenHelper.getWritableDatabase();, j'obtiens une exception de pointeur nul.
Code suit:
MainWindow.java
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
/**
* Check for DB, if none, d/l from web server
*/
Uri first_use = Rules.CONTENT_URI;
ContentResolver cr = getContentResolver();
Cursor c = cr.query(first_use, null, null, null, null);
if(c == null){
ContentProvider cp = new CoreRulesProvider();
if (cp.onCreate()) {
ContentValues values = new ContentValues();
values.put(Rules._ID, 1);
values.put(Rules.TERM, "Player");
values.put(Rules.TEXT, "You, the person reading these rules, are a Player.");
cp.insert(Rules.CONTENT_URI, values);
}
}
RulesContentProvider.java
package com.vortex.rules;
import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.Context;
import android.content.UriMatcher;
import android.content.res.Resources;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteQueryBuilder;
import android.net.Uri;
import android.text.TextUtils;
import android.util.Log;
import java.util.HashMap;
import com.vortex.rules.Rule.Rules;
/**
* Provides access to a database of rules. Each rule has a TERM, the RULE itself, and a creation date and modified data.
* @author Michael Martin
*
*/
public class CoreRulesProvider extends ContentProvider {
private static final String TAG = "CoreRulesProvider";
private static final String DATABASE_NAME = "core_rules.db";
private static final int DATABASE_VERSION = 2;
private static final String RULES_TABLE_NAME = "rules";
private static HashMap<String, String> sRulesProjectionMap;
private static HashMap<String, String> sLiveFolderProjectionMap;
private static final int RULES = 1;
private static final int RULE_ID = 2;
private static final int LIVE_FOLDER_RULES = 3;
private static final UriMatcher sUriMatcher;
/**
* This class helps open, create, and upgrade the database file.
*/
private static class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE " + RULES_TABLE_NAME + " ("
+ Rules._ID + " INTEGER PRIMARY KEY,"
+ Rules.TERM + " TEXT,"
+ Rules.TEXT + " LONGTEXT"
+ ");");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
+newVersion + ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS rules");
onCreate(db);
}
}
/**
* END OF DatabaseHelper CLASS!!!!!
*/
private DatabaseHelper mOpenHelper;
@Override
public boolean onCreate() {
mOpenHelper = new DatabaseHelper(getContext());
return true;
}
@Override
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
SQLiteQueryBuilder qb = new SQLiteQueryBuilder();
qb.setTables(RULES_TABLE_NAME);
switch (sUriMatcher.match(uri)) {
case RULES:
qb.setProjectionMap(sRulesProjectionMap);
break;
case RULE_ID:
qb.setProjectionMap(sLiveFolderProjectionMap);
qb.appendWhere(Rules._ID + "=" + uri.getPathSegments().get(1));
break;
default:
throw new IllegalArgumentException("Uknown URI " + uri);
}
//If no sort order is specified, use the default
String orderBy;
if (TextUtils.isEmpty(sortOrder)) {orderBy = Rules.DEFAULT_SORT_ORDER;
} else {
orderBy = sortOrder;
}
//Get the database and run the query
SQLiteDatabase db = mOpenHelper.getReadableDatabase();
Cursor c = qb.query(db, projection, selection, selectionArgs, null, null, orderBy);
//Tell the cursor what uri to watch, so it knows when its source data changes
c.setNotificationUri(getContext().getContentResolver(), uri);
return c;
}
@Override
public String getType(Uri uri) {
switch (sUriMatcher.match(uri)) {
case RULES:
case LIVE_FOLDER_RULES:
return Rules.CONTENT_TYPE;
case RULE_ID:
return Rules.CONTENT_ITEM_TYPE;
default:
throw new IllegalArgumentException("Uknown URI " + uri);
}
}
public Uri insert(Uri uri, ContentValues initialValues) {
//Validate the requested uri
if (sUriMatcher.match(uri) != RULES) {
throw new IllegalArgumentException("Uknown URI " + uri);
}
ContentValues values;
if (initialValues != null) {
values = new ContentValues(initialValues);
} else {
values = new ContentValues();
}
//Make sure that the fields are all set
if (values.containsKey(Rules.TERM) == false) {
Resources r = Resources.getSystem();
values.put(Rules.TERM, r.getString(android.R.string.untitled));
}
if (values.containsKey(Rules.TEXT) == false) {
values.put(Rules.TEXT, "");
}
SQLiteDatabase db = mOpenHelper.getWritableDatabase();
long rowId = db.insert(RULES_TABLE_NAME, Rules.TEXT, values);
if (rowId > 0) {
Uri ruleUri = ContentUris.withAppendedId(Rules.CONTENT_URI, rowId);
getContext().getContentResolver().notifyChange(ruleUri, null);
return ruleUri;
}
throw new SQLException("Failed to insert row into " + uri);
}
public int delete(Uri uri, String where, String[] whereArgs) {
SQLiteDatabase db = mOpenHelper.getWritableDatabase();
int count;
switch (sUriMatcher.match(uri)) {
case RULES:
count = db.delete(RULES_TABLE_NAME, where, whereArgs);
break;
case RULE_ID:
String ruleId = uri.getPathSegments().get(1);
count = db.delete(RULES_TABLE_NAME, Rules._ID + "=" + ruleId
+ (!TextUtils.isEmpty(where) ? " AND (" + where + ')' : ""),
whereArgs);
break;
default:
throw new IllegalArgumentException("Uknown URI " + uri);
}
getContext().getContentResolver().notifyChange(uri, null);
return count;
}
@Override
public int update(Uri uri, ContentValues values, String where, String[] whereArgs) {
SQLiteDatabase db = mOpenHelper.getWritableDatabase();
int count;
switch (sUriMatcher.match(uri)) {
case RULES:
count = db.update(RULES_TABLE_NAME, values, where, whereArgs);
break;
case RULE_ID:
String ruleId = uri.getPathSegments().get(1);
count = db.update(RULES_TABLE_NAME, values, Rules._ID + "=" + ruleId
+ (!TextUtils.isEmpty(where) ? " AND (" + where + ')' : "")
, whereArgs);
break;
default:
throw new IllegalArgumentException("Unknown URI " + uri);
}
getContext().getContentResolver().notifyChange(uri, null);
return count;
}
static {
sUriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
sUriMatcher.addURI(Rule.AUTHORITY, "rules", RULES);
sUriMatcher.addURI(Rule.AUTHORITY, "rules/#", RULE_ID);
sUriMatcher.addURI(Rule.AUTHORITY, "live_folders/rules", LIVE_FOLDER_RULES);
sRulesProjectionMap = new HashMap<String, String>();
sRulesProjectionMap.put(Rules._ID, Rules._ID);
sRulesProjectionMap.put(Rules.TERM, Rules.TERM);
sRulesProjectionMap.put(Rules.TEXT, Rules.TEXT);
}
}
Stack Trace
07-30 10: 22: 19,078: ERREUR/AndroidRuntime (10903): gestionnaire Uncaught: fil conducteur sortant en raison d'exception non interceptée octobre 7 à 30: 22: 19,208: ERREUR/AndroidRuntime (10903): java. lang.RuntimeException: Impossible de démarrer l'activité ComponentInfo {com.vortex.rules/com.vortex.rules.MainWindow}: java.lang.NullPointerException 07-30 10: 22: 19.208: ERROR/AndroidRuntime (10903): sur android. app.ActivityThread.performLaunchActivity (ActivityThread.java:2444) 07-30 10: 22: 19.208: ERREUR/AndroidRuntime (10903): at android.app.ActivityThread.handleLaunchActivity (ActivityThread.java:2460) 07-30 10: 22: 19.208: ERROR/AndroidRuntime (10903): at android.app.ActivityThread.access $ 2300 (ActivityThread.java:119) 07-30 10: 22: 19.20 8: ERROR/AndroidRuntime (10903): à l'adresse android.app.ActivityThread $ H.handleMessage (ActivityThread.java:1837) 07-30 10: 22: 19.208: ERROR/AndroidRuntime (10903): à android.os.Handler. dispatchMessage (Handler.java:99) 07-30 10: 22: 19.208: ERROR/AndroidRuntime (10903): à l'adresse android.os.Looper.loop (Looper.java:123) 07-30 10: 22: 19.208: ERREUR/AndroidRuntime (10903): at android.app.ActivityThread.main (ActivityThread.java:4246) 07-30 10: 22: 19.208: ERROR/AndroidRuntime (10903): à java.lang.reflect.Method.invokeNative (Méthode native) 07-30 10: 22: 19.208: ERROR/AndroidRuntime (10903): à java.lang.reflect.Method.invoke (Method.java:521) 07-30 10: 22: 19.208: ERROR/AndroidRuntime (10903): at com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run (ZygoteInit.java:791) 07-30 10: 22: 19.208: E RROR/AndroidRuntime (10903): à com.android.internal.os.ZygoteInit.main (ZygoteInit.java:549) 07-30 10: 22: 19.208: ERROR/AndroidRuntime (10903): à dalvik.system.NativeStart. main (méthode native) 07-30 10: 22: 19.208: ERROR/AndroidRuntime (10903): Causée par: java.lang.NullPointerException 07-30 10: 22: 19.208: ERROR/AndroidRuntime (10903): at android. database.sqlite.SQLiteOpenHelper.getWritableDatabase (SQLiteOpenHelper.java:98) 07-30 10: 22: 19.208: ERROR/AndroidRuntime (10903): à com.vortex.rules.CoreRulesProvider.insert (CoreRulesProvider.java:157) 07 -30 10: 22: 19.208: ERROR/AndroidRuntime (10903): à com.vortex.rules.MainWindow.onCreate (MainWindow.java:42) 07-30 10: 22: 19.208: ERROR/AndroidRuntime (10903): à android.app.Instrumentation.callActivityOnCreate (Instrumentation.java:1123) 07-30 10: 22: 19.208: ERROR/AndroidRuntime (10903): at android.app.ActivityThread.performLaunchActivity (ActivityThread.java: 2407) 07-30 10: 22: 19.208: ERROR/AndroidRuntime (10903): ... 11 plus