Android.database.CursorIndexOutOfBoundsException:请求索引0,大小为0-s
我在使用SQLite数据库时遇到此错误Android.database.CursorIndexOutOfBoundsException:请求索引0,大小为0-s,android,sqlite,Android,Sqlite,我在使用SQLite数据库时遇到此错误 07-16 17:45:13.106: E/AndroidRuntime(7703): Caused by: android.database.CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0 我正在使用SQLite数据库在其中存储图书对象 public class MySQLiteHelper extends SQLiteOpenHelper { //
07-16 17:45:13.106: E/AndroidRuntime(7703): Caused by:
android.database.CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0
我正在使用SQLite数据库在其中存储图书对象
public class MySQLiteHelper extends SQLiteOpenHelper {
// Database Version
private static final int DATABASE_VERSION = 1;
// Database Name
private static final String DATABASE_NAME = "BookDB";
public MySQLiteHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
// SQL statement to create book table
String CREATE_BOOK_TABLE = "CREATE TABLE books ( " +
"id INTEGER PRIMARY KEY AUTOINCREMENT, " +
"title TEXT, "+
"author TEXT )";
// create books table
db.execSQL(CREATE_BOOK_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// Drop older books table if existed
db.execSQL("DROP TABLE IF EXISTS books");
// create fresh books table
this.onCreate(db);
}
//---------------------------------------------------------------------
/**
* CRUD operations (create "add", read "get", update, delete) book + get all books + delete all books
*/
// Books table name
private static final String TABLE_BOOKS = "books";
// Books Table Columns names
private static final String KEY_ID = "id";
private static final String KEY_TITLE = "title";
private static final String KEY_AUTHOR = "author";
private static final String[] COLUMNS = {KEY_ID,KEY_TITLE,KEY_AUTHOR};
public void addBook(Book book){
Log.d("addBook", book.toString());
// 1. get reference to writable DB
SQLiteDatabase db = this.getWritableDatabase();
// 2. create ContentValues to add key "column"/value
ContentValues values = new ContentValues();
values.put(KEY_TITLE, book.getTitle()); // get title
values.put(KEY_AUTHOR, book.getAuthor()); // get author
// 3. insert
db.insert(TABLE_BOOKS, // table
null, //nullColumnHack
values); // key/value -> keys = column names/ values = column values
// 4. close
db.close();
}
public Book getBook(int id){
// 1. get reference to readable DB
SQLiteDatabase db = this.getReadableDatabase();
// 2. build query
Cursor cursor =
db.query(TABLE_BOOKS, // a. table
COLUMNS, // b. column names
" id = ?", // c. selections
new String[] { String.valueOf(id) }, // d. selections args
null, // e. group by
null, // f. having
null, // g. order by
null); // h. limit
// 3. if we got results get the first one
if (cursor != null)
cursor.moveToFirst();
// 4. build book object
Book book = new Book();
book.setId(Integer.parseInt(cursor.getString(0)));
book.setTitle(cursor.getString(1));
book.setAuthor(cursor.getString(2));
Log.d("getBook("+id+")", book.toString());
// 5. return book
return book;
}
// Get All Books
public List<Book> getAllBooks() {
List<Book> books = new LinkedList<Book>();
// 1. build the query
String query = "SELECT * FROM " + TABLE_BOOKS;
// 2. get reference to writable DB
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(query, null);
// 3. go over each row, build book and add it to list
Book book = null;
if (cursor.moveToFirst()) {
do {
book = new Book();
book.setId(Integer.parseInt(cursor.getString(0)));
book.setTitle(cursor.getString(1));
book.setAuthor(cursor.getString(2));
// Add book to books
books.add(book);
} while (cursor.moveToNext());
}
Log.d("getAllBooks()", books.toString());
// return books
return books;
}
// Updating single book
public int updateBook(Book book) {
// 1. get reference to writable DB
SQLiteDatabase db = this.getWritableDatabase();
// 2. create ContentValues to add key "column"/value
ContentValues values = new ContentValues();
values.put("title", book.getTitle()); // get title
values.put("author", book.getAuthor()); // get author
// 3. updating row
int i = db.update(TABLE_BOOKS, //table
values, // column/value
KEY_ID+" = ?", // selections
new String[] { String.valueOf(book.getId()) }); //selection args
// 4. close
db.close();
return i;
}
// Deleting single book
public void deleteBook(Book book) {
// 1. get reference to writable DB
SQLiteDatabase db = this.getWritableDatabase();
// 2. delete
db.delete(TABLE_BOOKS,
KEY_ID+" = ?",
new String[] { String.valueOf(book.getId()) });
// 3. close
db.close();
Log.d("deleteBook", book.toString());
}
}
您必须检查光标是否有任何线条。像这样:
// 3. if we got results get the first one
if (cursor.moveToFirst()){
// do the work
}
如果游标不为空,则cursor.moveToFirst返回true,否则返回false
当光标为空时,您试图读取光标,因此出现异常
编辑:它在您的getBook0上,改为调用getBook1,第一个自动递增的id值是1,而不是0。并更改光标检查表达式。尝试使用
if(v != null && v.moveToFirst()) {
//your code
}
它工作了4分钟只需在下面的代码中尝试单个条件,您必须首先检查光标是否为空,然后在移动到开始位置后不要忘记在工作完成后关闭它
Cursor cursor = db.query(...);if (cursor != null) {
if (cursor.moveToFirst()) {
//do your stuff
}
cursor.close();
}
现在,如果您想检查多个列,只需替换whilecondition而不是if
谢谢我认为您正在两次初始化同名的游标,请关闭第一个并尝试运行该程序。@ffdzs它是不同的。试试看。很抱歉,这个网站禁止了我们。试着另找一个看看你的答案“禁止”是什么意思。那是个错误。您的客户端无权从此服务器获取URL/reference/android/database/Cursor.html。客户端IP地址:151.**.46.165很抱歉,您的国家/地区不提供此服务。