The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2006 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package android.database; |
| 18 | |
| 19 | import android.content.ContentResolver; |
| 20 | import android.net.Uri; |
| 21 | import android.os.Bundle; |
| 22 | |
| 23 | import java.util.Map; |
| 24 | |
| 25 | /** |
| 26 | * This interface provides random read-write access to the result set returned |
| 27 | * by a database query. |
| 28 | */ |
| 29 | public interface Cursor { |
| 30 | /** |
| 31 | * Returns the numbers of rows in the cursor. |
| 32 | * |
| 33 | * @return the number of rows in the cursor. |
| 34 | */ |
| 35 | int getCount(); |
| 36 | |
| 37 | /** |
| 38 | * Returns the current position of the cursor in the row set. |
| 39 | * The value is zero-based. When the row set is first returned the cursor |
| 40 | * will be at positon -1, which is before the first row. After the |
| 41 | * last row is returned another call to next() will leave the cursor past |
| 42 | * the last entry, at a position of count(). |
| 43 | * |
| 44 | * @return the current cursor position. |
| 45 | */ |
| 46 | int getPosition(); |
| 47 | |
| 48 | /** |
| 49 | * Move the cursor by a relative amount, forward or backward, from the |
| 50 | * current position. Positive offsets move forwards, negative offsets move |
| 51 | * backwards. If the final position is outside of the bounds of the result |
| 52 | * set then the resultant position will be pinned to -1 or count() depending |
| 53 | * on whether the value is off the front or end of the set, respectively. |
| 54 | * |
| 55 | * <p>This method will return true if the requested destination was |
| 56 | * reachable, otherwise, it returns false. For example, if the cursor is at |
| 57 | * currently on the second entry in the result set and move(-5) is called, |
| 58 | * the position will be pinned at -1, and false will be returned. |
| 59 | * |
| 60 | * @param offset the offset to be applied from the current position. |
| 61 | * @return whether the requested move fully succeeded. |
| 62 | */ |
| 63 | boolean move(int offset); |
| 64 | |
| 65 | /** |
| 66 | * Move the cursor to an absolute position. The valid |
| 67 | * range of values is -1 <= position <= count. |
| 68 | * |
| 69 | * <p>This method will return true if the request destination was reachable, |
| 70 | * otherwise, it returns false. |
| 71 | * |
| 72 | * @param position the zero-based position to move to. |
| 73 | * @return whether the requested move fully succeeded. |
| 74 | */ |
| 75 | boolean moveToPosition(int position); |
| 76 | |
| 77 | /** |
| 78 | * Move the cursor to the first row. |
| 79 | * |
| 80 | * <p>This method will return false if the cursor is empty. |
| 81 | * |
| 82 | * @return whether the move succeeded. |
| 83 | */ |
| 84 | boolean moveToFirst(); |
| 85 | |
| 86 | /** |
| 87 | * Move the cursor to the last row. |
| 88 | * |
| 89 | * <p>This method will return false if the cursor is empty. |
| 90 | * |
| 91 | * @return whether the move succeeded. |
| 92 | */ |
| 93 | boolean moveToLast(); |
| 94 | |
| 95 | /** |
| 96 | * Move the cursor to the next row. |
| 97 | * |
| 98 | * <p>This method will return false if the cursor is already past the |
| 99 | * last entry in the result set. |
| 100 | * |
| 101 | * @return whether the move succeeded. |
| 102 | */ |
| 103 | boolean moveToNext(); |
| 104 | |
| 105 | /** |
| 106 | * Move the cursor to the previous row. |
| 107 | * |
| 108 | * <p>This method will return false if the cursor is already before the |
| 109 | * first entry in the result set. |
| 110 | * |
| 111 | * @return whether the move succeeded. |
| 112 | */ |
| 113 | boolean moveToPrevious(); |
| 114 | |
| 115 | /** |
| 116 | * Returns whether the cursor is pointing to the first row. |
| 117 | * |
| 118 | * @return whether the cursor is pointing at the first entry. |
| 119 | */ |
| 120 | boolean isFirst(); |
| 121 | |
| 122 | /** |
| 123 | * Returns whether the cursor is pointing to the last row. |
| 124 | * |
| 125 | * @return whether the cursor is pointing at the last entry. |
| 126 | */ |
| 127 | boolean isLast(); |
| 128 | |
| 129 | /** |
| 130 | * Returns whether the cursor is pointing to the position before the first |
| 131 | * row. |
| 132 | * |
| 133 | * @return whether the cursor is before the first result. |
| 134 | */ |
| 135 | boolean isBeforeFirst(); |
| 136 | |
| 137 | /** |
| 138 | * Returns whether the cursor is pointing to the position after the last |
| 139 | * row. |
| 140 | * |
| 141 | * @return whether the cursor is after the last result. |
| 142 | */ |
| 143 | boolean isAfterLast(); |
| 144 | |
| 145 | /** |
| 146 | * Removes the row at the current cursor position from the underlying data |
| 147 | * store. After this method returns the cursor will be pointing to the row |
| 148 | * after the row that is deleted. This has the side effect of decrementing |
| 149 | * the result of count() by one. |
| 150 | * <p> |
| 151 | * The query must have the row ID column in its selection, otherwise this |
| 152 | * call will fail. |
| 153 | * |
| 154 | * @hide |
| 155 | * @return whether the record was successfully deleted. |
| 156 | * @deprecated use {@link ContentResolver#delete(Uri, String, String[])} |
| 157 | */ |
| 158 | @Deprecated |
| 159 | boolean deleteRow(); |
| 160 | |
| 161 | /** |
| 162 | * Returns the zero-based index for the given column name, or -1 if the column doesn't exist. |
| 163 | * If you expect the column to exist use {@link #getColumnIndexOrThrow(String)} instead, which |
| 164 | * will make the error more clear. |
| 165 | * |
| 166 | * @param columnName the name of the target column. |
| 167 | * @return the zero-based column index for the given column name, or -1 if |
| 168 | * the column name does not exist. |
| 169 | * @see #getColumnIndexOrThrow(String) |
| 170 | */ |
| 171 | int getColumnIndex(String columnName); |
| 172 | |
| 173 | /** |
| 174 | * Returns the zero-based index for the given column name, or throws |
| 175 | * {@link IllegalArgumentException} if the column doesn't exist. If you're not sure if |
| 176 | * a column will exist or not use {@link #getColumnIndex(String)} and check for -1, which |
| 177 | * is more efficient than catching the exceptions. |
| 178 | * |
| 179 | * @param columnName the name of the target column. |
| 180 | * @return the zero-based column index for the given column name |
| 181 | * @see #getColumnIndex(String) |
| 182 | * @throws IllegalArgumentException if the column does not exist |
| 183 | */ |
| 184 | int getColumnIndexOrThrow(String columnName) throws IllegalArgumentException; |
| 185 | |
| 186 | /** |
| 187 | * Returns the column name at the given zero-based column index. |
| 188 | * |
| 189 | * @param columnIndex the zero-based index of the target column. |
| 190 | * @return the column name for the given column index. |
| 191 | */ |
| 192 | String getColumnName(int columnIndex); |
| 193 | |
| 194 | /** |
| 195 | * Returns a string array holding the names of all of the columns in the |
| 196 | * result set in the order in which they were listed in the result. |
| 197 | * |
| 198 | * @return the names of the columns returned in this query. |
| 199 | */ |
| 200 | String[] getColumnNames(); |
| 201 | |
| 202 | /** |
| 203 | * Return total number of columns |
| 204 | * @return number of columns |
| 205 | */ |
| 206 | int getColumnCount(); |
| 207 | |
| 208 | /** |
| 209 | * Returns the value of the requested column as a byte array. |
| 210 | * |
| 211 | * <p>If the native content of that column is not blob exception may throw |
| 212 | * |
| 213 | * @param columnIndex the zero-based index of the target column. |
| 214 | * @return the value of that column as a byte array. |
| 215 | */ |
| 216 | byte[] getBlob(int columnIndex); |
| 217 | |
| 218 | /** |
| 219 | * Returns the value of the requested column as a String. |
| 220 | * |
| 221 | * <p>If the native content of that column is not text the result will be |
| 222 | * the result of passing the column value to String.valueOf(x). |
| 223 | * |
| 224 | * @param columnIndex the zero-based index of the target column. |
| 225 | * @return the value of that column as a String. |
| 226 | */ |
| 227 | String getString(int columnIndex); |
| 228 | |
| 229 | /** |
| 230 | * Retrieves the requested column text and stores it in the buffer provided. |
| 231 | * If the buffer size is not sufficient, a new char buffer will be allocated |
| 232 | * and assigned to CharArrayBuffer.data |
| 233 | * @param columnIndex the zero-based index of the target column. |
| 234 | * if the target column is null, return buffer |
| 235 | * @param buffer the buffer to copy the text into. |
| 236 | */ |
| 237 | void copyStringToBuffer(int columnIndex, CharArrayBuffer buffer); |
| 238 | |
| 239 | /** |
| 240 | * Returns the value of the requested column as a short. |
| 241 | * |
| 242 | * <p>If the native content of that column is not numeric the result will be |
| 243 | * the result of passing the column value to Short.valueOf(x). |
| 244 | * |
| 245 | * @param columnIndex the zero-based index of the target column. |
| 246 | * @return the value of that column as a short. |
| 247 | */ |
| 248 | short getShort(int columnIndex); |
| 249 | |
| 250 | /** |
| 251 | * Returns the value of the requested column as an int. |
| 252 | * |
| 253 | * <p>If the native content of that column is not numeric the result will be |
| 254 | * the result of passing the column value to Integer.valueOf(x). |
| 255 | * |
| 256 | * @param columnIndex the zero-based index of the target column. |
| 257 | * @return the value of that column as an int. |
| 258 | */ |
| 259 | int getInt(int columnIndex); |
| 260 | |
| 261 | /** |
| 262 | * Returns the value of the requested column as a long. |
| 263 | * |
| 264 | * <p>If the native content of that column is not numeric the result will be |
| 265 | * the result of passing the column value to Long.valueOf(x). |
| 266 | * |
| 267 | * @param columnIndex the zero-based index of the target column. |
| 268 | * @return the value of that column as a long. |
| 269 | */ |
| 270 | long getLong(int columnIndex); |
| 271 | |
| 272 | /** |
| 273 | * Returns the value of the requested column as a float. |
| 274 | * |
| 275 | * <p>If the native content of that column is not numeric the result will be |
| 276 | * the result of passing the column value to Float.valueOf(x). |
| 277 | * |
| 278 | * @param columnIndex the zero-based index of the target column. |
| 279 | * @return the value of that column as a float. |
| 280 | */ |
| 281 | float getFloat(int columnIndex); |
| 282 | |
| 283 | /** |
| 284 | * Returns the value of the requested column as a double. |
| 285 | * |
| 286 | * <p>If the native content of that column is not numeric the result will be |
| 287 | * the result of passing the column value to Double.valueOf(x). |
| 288 | * |
| 289 | * @param columnIndex the zero-based index of the target column. |
| 290 | * @return the value of that column as a double. |
| 291 | */ |
| 292 | double getDouble(int columnIndex); |
| 293 | |
| 294 | /** |
| 295 | * Returns <code>true</code> if the value in the indicated column is null. |
| 296 | * |
| 297 | * @param columnIndex the zero-based index of the target column. |
| 298 | * @return whether the column value is null. |
| 299 | */ |
| 300 | boolean isNull(int columnIndex); |
| 301 | |
| 302 | /** |
| 303 | * Returns <code>true</code> if the cursor supports updates. |
| 304 | * |
| 305 | * @return whether the cursor supports updates. |
| 306 | * @hide |
| 307 | * @deprecated use the {@link ContentResolver} update methods instead of the Cursor |
| 308 | * update methods |
| 309 | */ |
| 310 | @Deprecated |
| 311 | boolean supportsUpdates(); |
| 312 | |
| 313 | /** |
| 314 | * Returns <code>true</code> if there are pending updates that have not yet been committed. |
| 315 | * |
| 316 | * @return <code>true</code> if there are pending updates that have not yet been committed. |
| 317 | * @hide |
| 318 | * @deprecated use the {@link ContentResolver} update methods instead of the Cursor |
| 319 | * update methods |
| 320 | */ |
| 321 | @Deprecated |
| 322 | boolean hasUpdates(); |
| 323 | |
| 324 | /** |
| 325 | * Updates the value for the given column in the row the cursor is |
| 326 | * currently pointing at. Updates are not committed to the backing store |
| 327 | * until {@link #commitUpdates()} is called. |
| 328 | * |
| 329 | * @param columnIndex the zero-based index of the target column. |
| 330 | * @param value the new value. |
| 331 | * @return whether the operation succeeded. |
| 332 | * @hide |
| 333 | * @deprecated use the {@link ContentResolver} update methods instead of the Cursor |
| 334 | * update methods |
| 335 | */ |
| 336 | @Deprecated |
| 337 | boolean updateBlob(int columnIndex, byte[] value); |
| 338 | |
| 339 | /** |
| 340 | * Updates the value for the given column in the row the cursor is |
| 341 | * currently pointing at. Updates are not committed to the backing store |
| 342 | * until {@link #commitUpdates()} is called. |
| 343 | * |
| 344 | * @param columnIndex the zero-based index of the target column. |
| 345 | * @param value the new value. |
| 346 | * @return whether the operation succeeded. |
| 347 | * @hide |
| 348 | * @deprecated use the {@link ContentResolver} update methods instead of the Cursor |
| 349 | * update methods |
| 350 | */ |
| 351 | @Deprecated |
| 352 | boolean updateString(int columnIndex, String value); |
| 353 | |
| 354 | /** |
| 355 | * Updates the value for the given column in the row the cursor is |
| 356 | * currently pointing at. Updates are not committed to the backing store |
| 357 | * until {@link #commitUpdates()} is called. |
| 358 | * |
| 359 | * @param columnIndex the zero-based index of the target column. |
| 360 | * @param value the new value. |
| 361 | * @return whether the operation succeeded. |
| 362 | * @hide |
| 363 | * @deprecated use the {@link ContentResolver} update methods instead of the Cursor |
| 364 | * update methods |
| 365 | */ |
| 366 | @Deprecated |
| 367 | boolean updateShort(int columnIndex, short value); |
| 368 | |
| 369 | /** |
| 370 | * Updates the value for the given column in the row the cursor is |
| 371 | * currently pointing at. Updates are not committed to the backing store |
| 372 | * until {@link #commitUpdates()} is called. |
| 373 | * |
| 374 | * @param columnIndex the zero-based index of the target column. |
| 375 | * @param value the new value. |
| 376 | * @return whether the operation succeeded. |
| 377 | * @hide |
| 378 | * @deprecated use the {@link ContentResolver} update methods instead of the Cursor |
| 379 | * update methods |
| 380 | */ |
| 381 | @Deprecated |
| 382 | boolean updateInt(int columnIndex, int value); |
| 383 | |
| 384 | /** |
| 385 | * Updates the value for the given column in the row the cursor is |
| 386 | * currently pointing at. Updates are not committed to the backing store |
| 387 | * until {@link #commitUpdates()} is called. |
| 388 | * |
| 389 | * @param columnIndex the zero-based index of the target column. |
| 390 | * @param value the new value. |
| 391 | * @return whether the operation succeeded. |
| 392 | * @hide |
| 393 | * @deprecated use the {@link ContentResolver} update methods instead of the Cursor |
| 394 | * update methods |
| 395 | */ |
| 396 | @Deprecated |
| 397 | boolean updateLong(int columnIndex, long value); |
| 398 | |
| 399 | /** |
| 400 | * Updates the value for the given column in the row the cursor is |
| 401 | * currently pointing at. Updates are not committed to the backing store |
| 402 | * until {@link #commitUpdates()} is called. |
| 403 | * |
| 404 | * @param columnIndex the zero-based index of the target column. |
| 405 | * @param value the new value. |
| 406 | * @return whether the operation succeeded. |
| 407 | * @hide |
| 408 | * @deprecated use the {@link ContentResolver} update methods instead of the Cursor |
| 409 | * update methods |
| 410 | */ |
| 411 | @Deprecated |
| 412 | boolean updateFloat(int columnIndex, float value); |
| 413 | |
| 414 | /** |
| 415 | * Updates the value for the given column in the row the cursor is |
| 416 | * currently pointing at. Updates are not committed to the backing store |
| 417 | * until {@link #commitUpdates()} is called. |
| 418 | * |
| 419 | * @param columnIndex the zero-based index of the target column. |
| 420 | * @param value the new value. |
| 421 | * @return whether the operation succeeded. |
| 422 | * @hide |
| 423 | * @deprecated use the {@link ContentResolver} update methods instead of the Cursor |
| 424 | * update methods |
| 425 | */ |
| 426 | @Deprecated |
| 427 | boolean updateDouble(int columnIndex, double value); |
| 428 | |
| 429 | /** |
| 430 | * Removes the value for the given column in the row the cursor is |
| 431 | * currently pointing at. Updates are not committed to the backing store |
| 432 | * until {@link #commitUpdates()} is called. |
| 433 | * |
| 434 | * @param columnIndex the zero-based index of the target column. |
| 435 | * @return whether the operation succeeded. |
| 436 | * @hide |
| 437 | * @deprecated use the {@link ContentResolver} update methods instead of the Cursor |
| 438 | * update methods |
| 439 | */ |
| 440 | @Deprecated |
| 441 | boolean updateToNull(int columnIndex); |
| 442 | |
| 443 | /** |
| 444 | * Atomically commits all updates to the backing store. After completion, |
| 445 | * this method leaves the data in an inconsistent state and you should call |
| 446 | * {@link #requery} before reading data from the cursor again. |
| 447 | * |
| 448 | * @return whether the operation succeeded. |
| 449 | * @hide |
| 450 | * @deprecated use the {@link ContentResolver} update methods instead of the Cursor |
| 451 | * update methods |
| 452 | */ |
| 453 | @Deprecated |
| 454 | boolean commitUpdates(); |
| 455 | |
| 456 | /** |
| 457 | * Atomically commits all updates to the backing store, as well as the |
| 458 | * updates included in values. After completion, |
| 459 | * this method leaves the data in an inconsistent state and you should call |
| 460 | * {@link #requery} before reading data from the cursor again. |
| 461 | * |
| 462 | * @param values A map from row IDs to Maps associating column names with |
| 463 | * updated values. A null value indicates the field should be |
| 464 | removed. |
| 465 | * @return whether the operation succeeded. |
| 466 | * @hide |
| 467 | * @deprecated use the {@link ContentResolver} update methods instead of the Cursor |
| 468 | * update methods |
| 469 | */ |
| 470 | @Deprecated |
| 471 | boolean commitUpdates(Map<? extends Long, |
| 472 | ? extends Map<String,Object>> values); |
| 473 | |
| 474 | /** |
| 475 | * Reverts all updates made to the cursor since the last call to |
| 476 | * commitUpdates. |
| 477 | * @hide |
| 478 | * @deprecated use the {@link ContentResolver} update methods instead of the Cursor |
| 479 | * update methods |
| 480 | */ |
| 481 | @Deprecated |
| 482 | void abortUpdates(); |
| 483 | |
| 484 | /** |
| 485 | * Deactivates the Cursor, making all calls on it fail until {@link #requery} is called. |
| 486 | * Inactive Cursors use fewer resources than active Cursors. |
| 487 | * Calling {@link #requery} will make the cursor active again. |
| 488 | */ |
| 489 | void deactivate(); |
| 490 | |
| 491 | /** |
| 492 | * Performs the query that created the cursor again, refreshing its |
| 493 | * contents. This may be done at any time, including after a call to {@link |
| 494 | * #deactivate}. |
| 495 | * |
| 496 | * @return true if the requery succeeded, false if not, in which case the |
| 497 | * cursor becomes invalid. |
| 498 | */ |
| 499 | boolean requery(); |
| 500 | |
| 501 | /** |
| 502 | * Closes the Cursor, releasing all of its resources and making it completely invalid. |
| 503 | * Unlike {@link #deactivate()} a call to {@link #requery()} will not make the Cursor valid |
| 504 | * again. |
| 505 | */ |
| 506 | void close(); |
| 507 | |
| 508 | /** |
| 509 | * return true if the cursor is closed |
| 510 | * @return true if the cursor is closed. |
| 511 | */ |
| 512 | boolean isClosed(); |
| 513 | |
| 514 | /** |
| 515 | * Register an observer that is called when changes happen to the content backing this cursor. |
| 516 | * Typically the data set won't change until {@link #requery()} is called. |
| 517 | * |
| 518 | * @param observer the object that gets notified when the content backing the cursor changes. |
| 519 | * @see #unregisterContentObserver(ContentObserver) |
| 520 | */ |
| 521 | void registerContentObserver(ContentObserver observer); |
| 522 | |
| 523 | /** |
| 524 | * Unregister an observer that has previously been registered with this |
| 525 | * cursor via {@link #registerContentObserver}. |
| 526 | * |
| 527 | * @param observer the object to unregister. |
| 528 | * @see #registerContentObserver(ContentObserver) |
| 529 | */ |
| 530 | void unregisterContentObserver(ContentObserver observer); |
| 531 | |
| 532 | /** |
| 533 | * Register an observer that is called when changes happen to the contents |
| 534 | * of the this cursors data set, for example, when the data set is changed via |
| 535 | * {@link #requery()}, {@link #deactivate()}, or {@link #close()}. |
| 536 | * |
| 537 | * @param observer the object that gets notified when the cursors data set changes. |
| 538 | * @see #unregisterDataSetObserver(DataSetObserver) |
| 539 | */ |
| 540 | void registerDataSetObserver(DataSetObserver observer); |
| 541 | |
| 542 | /** |
| 543 | * Unregister an observer that has previously been registered with this |
| 544 | * cursor via {@link #registerContentObserver}. |
| 545 | * |
| 546 | * @param observer the object to unregister. |
| 547 | * @see #registerDataSetObserver(DataSetObserver) |
| 548 | */ |
| 549 | void unregisterDataSetObserver(DataSetObserver observer); |
| 550 | |
| 551 | /** |
| 552 | * Register to watch a content URI for changes. This can be the URI of a specific data row (for |
| 553 | * example, "content://my_provider_type/23"), or a a generic URI for a content type. |
| 554 | * |
| 555 | * @param cr The content resolver from the caller's context. The listener attached to |
| 556 | * this resolver will be notified. |
| 557 | * @param uri The content URI to watch. |
| 558 | */ |
| 559 | void setNotificationUri(ContentResolver cr, Uri uri); |
| 560 | |
| 561 | /** |
| 562 | * onMove() will only be called across processes if this method returns true. |
| 563 | * @return whether all cursor movement should result in a call to onMove(). |
| 564 | */ |
| 565 | boolean getWantsAllOnMoveCalls(); |
| 566 | |
| 567 | /** |
| 568 | * Returns a bundle of extra values. This is an optional way for cursors to provide out-of-band |
| 569 | * metadata to their users. One use of this is for reporting on the progress of network requests |
| 570 | * that are required to fetch data for the cursor. |
| 571 | * |
| 572 | * <p>These values may only change when requery is called. |
| 573 | * @return cursor-defined values, or Bundle.EMTPY if there are no values. Never null. |
| 574 | */ |
| 575 | Bundle getExtras(); |
| 576 | |
| 577 | /** |
| 578 | * This is an out-of-band way for the the user of a cursor to communicate with the cursor. The |
| 579 | * structure of each bundle is entirely defined by the cursor. |
| 580 | * |
| 581 | * <p>One use of this is to tell a cursor that it should retry its network request after it |
| 582 | * reported an error. |
| 583 | * @param extras extra values, or Bundle.EMTPY. Never null. |
| 584 | * @return extra values, or Bundle.EMTPY. Never null. |
| 585 | */ |
| 586 | Bundle respond(Bundle extras); |
| 587 | } |