SQLiteDatabase 的插入、删除、更新、查找等默认返回值是什么啊？
比如下面的更新操作，失败的时候应该返回什么值？
/**
* Convenience method for updating rows in the database.
*
* @param table the table to update in
* @param values a map from column names to new column values. null is a
* valid value that will be translated to NULL.
* @param whereClause the optional WHERE clause to apply when updating.
* Passing null will update all rows.
* @param whereArgs You may include ?s in the where clause, which
* will be replaced by the values from whereArgs. The values
* will be bound as Strings.
* @return the number of rows affected
*/
public int update(String table, ContentValues values, String whereClause, String[] whereArgs) {
return updateWithOnConflict(table, values, whereClause, whereArgs, CONFLICT_NONE);
}
/**
* Convenience method for updating rows in the database.
*
* @param table the table to update in
* @param values a map from column names to new column values. null is a
* valid value that will be translated to NULL.
* @param whereClause the optional WHERE clause to apply when updating.
* Passing null will update all rows.
* @param whereArgs You may include ?s in the where clause, which
* will be replaced by the values from whereArgs. The values
* will be bound as Strings.
* @param conflictAlgorithm for update conflict resolver
* @return the number of rows affected
*/
public int updateWithOnConflict(String table, ContentValues values,
String whereClause, String[] whereArgs, int conflictAlgorithm) {
if (values == null || values.size() == 0) {
throw new IllegalArgumentException("Empty values");
}
acquireReference();
try {
StringBuilder sql = new StringBuilder(120);
sql.append("UPDATE ");
sql.append(CONFLICT_VALUES[conflictAlgorithm]);
sql.append(table);
sql.append(" SET ");
// move all bind args to one array
int setValuesSize = values.size();
int bindArgsSize = (whereArgs == null) ? setValuesSize : (setValuesSize + whereArgs.length);
Object[] bindArgs = new Object[bindArgsSize];
int i = 0;
for (String colName : values.keySet()) {
sql.append((i > 0) ? "," : "");
sql.append(colName);
bindArgs[i++] = values.get(colName);
sql.append("=?");
}
if (whereArgs != null) {
for (i = setValuesSize; i < bindArgsSize; i++) {
bindArgs[i] = whereArgs[i - setValuesSize];
}
}
if (!TextUtils.isEmpty(whereClause)) {
sql.append(" WHERE ");
sql.append(whereClause);
}
SQLiteStatement statement = new SQLiteStatement(this, sql.toString(), bindArgs);
try {
return statement.executeUpdateDelete();
} finally {
statement.close();
}
} finally {
releaseReference();
}
}
失敗的話，要看你什麼何種原因吧，如果是sql寫錯了就直接拋出異常了。如果要更新的資料不存在一定是回傳0了啊，