我正在使用一个 android 内容提供程序，并且我有一些要插入数据的表。第一个表有三列，在我的 usecontentprovider 类中，我使用底部的 toast 消息显示正在添加的所有行。一切正常。然后我尝试包含另一个具有两列（id2，id3）的表，我尝试查询该表并显示正在添加的行，每当我这样做时，我都会收到一条错误消息，提示无法读取第 0 行，第 -1 列一个有 1 行 3 列的 CursorWindow。我不确定我做错了什么，所以任何帮助将不胜感激。
public class UseContentProvideActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// add the 1st course
ContentValues values = new ContentValues();
values.put(MyContentProvider._ID, 1510);
values.put(MyContentProvider.NAME, "Jordan");
values.put(MyContentProvider.GRADE, 9);
Uri uri = getContentResolver().insert(MyContentProvider.CONTENT_URI,
values);
ContentValues values2 = new ContentValues();
values2.put(MyContentProvider._ID2, 1510);
values2.put(MyContentProvider._ID3, 9000);
Uri uri2 = getContentResolver().insert(MyContentProvider.CONTENT_URI2,
values);
uri2 = getContentResolver().insert(
Uri.parse("content://cs.ecl.provider.Courses/friend"), values);
// query added highschooler
Toast.makeText(this, "Added Schooler:", Toast.LENGTH_SHORT).show();
Uri allDescs = Uri.parse("content://cs.ecl.provider.Courses/highschooler");
Cursor cl = managedQuery(allDescs, null, null, null, "name");
if (cl.moveToFirst()) {
do {
Toast.makeText(
this,
cl.getString(cl.getColumnIndex(MyContentProvider._ID))
+ ", "
+ cl.getString(cl
.getColumnIndex(MyContentProvider.NAME))
+ ", "
+ cl.getString(cl
.getColumnIndex(MyContentProvider.GRADE)),
Toast.LENGTH_LONG).show();
} while (cl.moveToNext());
}
//2nd table
// query added friends
Toast.makeText(this, "Added Friend:", Toast.LENGTH_SHORT).show();
Uri allDescs2 = Uri.parse("content://cs.ecl.provider.Courses/friend");
Cursor cl2 = managedQuery(allDescs2, null, null, null, "name");
if (cl2.moveToFirst()) {
do {
Toast.makeText(
this,
cl2.getString(cl2.getColumnIndex(MyContentProvider._ID2))
+ ", "
+ cl2.getString(cl2
.getColumnIndex(MyContentProvider._ID3))
,
Toast.LENGTH_LONG).show();
} while (cl2.moveToNext());
}
getContentResolver().delete(
Uri.parse("content://cs.ecl.provider.Courses/highschooler"), null,
null);
}
}
public class MyContentProvider extends ContentProvider {
public static final String PROVIDER_NAME = "cs.ecl.provider.Courses";
// first url
public static final Uri CONTENT_URI = Uri.parse("content://"
+ PROVIDER_NAME + "/highschooler");
// second url
public static final Uri CONTENT_URI2 = Uri.parse("content://"
+ PROVIDER_NAME + "/friend");
// third url
public static final Uri CONTENT_URI3 = Uri.parse("content://"
+ PROVIDER_NAME + "/like");
public static final String _ID = "_id";
public static final String NAME = "name";
public static final String GRADE = "grade";
public static final String _ID2 = "_id1";
public static final String _ID3 = "_id2";
private static final int COURSES = 1;
private static final int COURSE_ID = 2;
// 2nd
private static final int COURSES2 = 3;
private static final int COURSE2_ID = 4;
private static final UriMatcher uriMatcher;
static {
uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
uriMatcher.addURI(PROVIDER_NAME, "highschooler", COURSES);
uriMatcher.addURI(PROVIDER_NAME, "highschooler/#", COURSE_ID);
// second table
uriMatcher.addURI(PROVIDER_NAME, "friend", COURSES2);
uriMatcher.addURI(PROVIDER_NAME, "friend/#", COURSE2_ID);
}
// for using SQLite database
private SQLiteDatabase coursesDB;
private static final String DATABASE_NAME = "Lab2";
private static final String DATABASE_TABLE = "Highschooler";
// 2nd table
private static final String DATABASE_TABLE2 = "Friend";
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_CREATE = "create table "
// + DATABASE_TABLE + " (_id integer primary key autoincrement, "
+ DATABASE_TABLE + " (_id integer, "
+ "name text not null, grade integer);";
private static final String DATABASE_CREATE2 = "create table "
// + DATABASE_TABLE + " (_id integer primary key autoincrement, "
+ DATABASE_TABLE2 + " (_id1 integer, " + "_id2 integer);";
// for using SQLite database
private static class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(DATABASE_CREATE);
db.execSQL(DATABASE_CREATE2);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS descs");
onCreate(db);
}
}
@Override
public int delete(Uri arg0/* uri */, String arg1/* selection */,
String[] arg2/* delectionArgs */) {
int count = 0;
switch (uriMatcher.match(arg0)) {
case COURSES:
count = coursesDB.delete(DATABASE_TABLE, arg1, arg2);
break;
case COURSE_ID:
String id = arg0.getPathSegments().get(1);
count = coursesDB.delete(DATABASE_TABLE, _ID + " = " + id
+ (!TextUtils.isEmpty(arg1) ? " AND (" + arg1 + ')' : ""),
arg2);
break;
default:
throw new IllegalArgumentException("Unknown URI " + arg0);
}
getContext().getContentResolver().notifyChange(arg0, null);
return count;
}
@Override
public String getType(Uri uri) {
switch (uriMatcher.match(uri)) {
// get all courses
case COURSES:
return "vnd.android.cursor.dir/vnd.ecl.courses ";
// get one course
case COURSE_ID:
return "vnd.android.cursor.item/vnd.ecl.courses ";
// new stuff
// get all courses
case COURSES2:
return "vnd.android.cursor.dir/vnd.ecl.courses2 ";
// get one course
case COURSE2_ID:
return "vnd.android.cursor.item/vnd.ecl.courses2 ";
default:
throw new IllegalArgumentException("Unsupported URI: " + uri);
}
}
@Override
public Uri insert(Uri uri, ContentValues values) {
Uri _uri = null;
switch (uriMatcher.match(uri)){
case COURSES:
System.out.println("GOT TO INSERT1");
long _ID1 = coursesDB.insert(DATABASE_TABLE, "", values);
//---if added successfully---
if (_ID1 > 0) {
_uri = ContentUris.withAppendedId(CONTENT_URI, _ID1);
getContext().getContentResolver().notifyChange(_uri, null);
}
break;
case COURSES2:
System.out.println("GOT TO INSERT2");
long _ID2 = coursesDB.insert(DATABASE_TABLE2, "", values);
//---if added successfully---
if (_ID2 > 0) {
_uri = ContentUris.withAppendedId(CONTENT_URI2, _ID2);
getContext().getContentResolver().notifyChange(_uri, null);
}
break;
default: throw new SQLException("Failed to insert row into " + uri);
}
return _uri;
}
@Override
public boolean onCreate() {
Context context = getContext();
DatabaseHelper dbHelper = new DatabaseHelper(context);
coursesDB = dbHelper.getWritableDatabase();
return (coursesDB == null) ? false : true;
}
@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
SQLiteQueryBuilder sqlBuilder = new SQLiteQueryBuilder();
sqlBuilder.setTables(DATABASE_TABLE);
if (uriMatcher.match(uri) == COURSE_ID)
// -- if getting one course --
sqlBuilder.appendWhere(_ID + " = " + uri.getPathSegments().get(1));
if (sortOrder == null || sortOrder == "")
sortOrder = NAME;
Cursor cl = sqlBuilder.query(coursesDB, projection, selection,
selectionArgs, null, null, sortOrder);
// register to watch a content URI for changes
cl.setNotificationUri(getContext().getContentResolver(), uri);
return cl;
}
@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
int count = 0;
switch (uriMatcher.match(uri)) {
case COURSES:
count = coursesDB.update(DATABASE_TABLE, values, selection,
selectionArgs);
break;
case COURSE_ID:
count = coursesDB.update(
DATABASE_TABLE,
values,
_ID
+ " = "
+ uri.getPathSegments().get(1)
+ (!TextUtils.isEmpty(selection) ? " AND ("
+ selection + ')' : ""), selectionArgs);
break;
default:
throw new IllegalArgumentException("Unknown URI " + uri);
}
getContext().getContentResolver().notifyChange(uri, null);
return count;
}
}