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This article introduces the relevant knowledge of "how to operate the database in Android". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

A good habit is to create a helper class to simplify your Android database interaction. Consider creating a database adapter to add a wrapper layer that interacts with the database. It should provide intuitive, strongly typed methods, such as adding, deleting, and updating items. The database adapter should also handle queries and wrappers for creating, opening, and closing databases.

It also often uses static Android database constants to define table names, column names, and column indexes. The following code snippet shows the framework of a standard database adapter class. It includes an extension of the SQLiteOpenHelper class to simplify opening, creating, and updating databases.

Import android.content.Context; import android.database.*; import android.database.sqlite.*; import android.database.sqlite.SQLiteDatabase.CursorFactory; import android.util.Log; public class MyDBAdapter {/ / The name and column index of each column in your database. Public static final String KEY_NAME= "name"; public static final int NAME_COLUMN = 1; / / TODO: Create public field for each column in your table. / / SQL Statement to create a new database. Private static final String DATABASE_CREATE = "create table" + DATABASE_TABLE + "(" + KEY_ID + "integer primary key autoincrement," + KEY_NAME + "text not null);"; / / Variable to hold the database instance private SQLiteDatabase db; / / Context of the application using the database. Private final Context context; / / Database open/upgrade helper private myDbHelper dbHelper; public MyDBAdapter (Context _ context) {context = _ context; dbHelper = new myDbHelper (context, DATABASE_NAME, null, DATABASE_VERSION);} public MyDBAdapter open () throws SQLException {db = dbHelper.getWritableDatabase (); return this;} public void close () {db.close ();} public long insertEntry (MyObject _ myObject) {ContentValues contentValues = new ContentValues () / / TODO fill in ContentValues to represent the new row return db.insert (DATABASE_TABLE, null, contentValues);} public boolean removeEntry (long _ rowIndex) {return db.delete (DATABASE_TABLE, KEY_ID + "=" + _ rowIndex, null) > 0;} public Cursor getAllEntries () {return db.query (DATABASE_TABLE, new String [] {KEY_ID, KEY_NAME}, null, null) } public MyObject getEntry (long _ rowIndex) {MyObject objectInstance = new MyObject (); / / TODO Return a cursor to a row from the database and / / use the values to populate an instance of MyObject return objectInstance;} public int updateEntry (long _ rowIndex, MyObject _ myObject) {String where = KEY_ID + "=" + _ rowIndex; ContentValues contentValues = new ContentValues (); / / TODO fill in the ContentValue based on the new object return db.update (DATABASE_TABLE, contentValues, where, null) } private static class myDbHelper extends SQLiteOpenHelper {public myDbHelper (Context context, String name, CursorFactory factory, int version) {super (context, name, factory, version);} / Called when no database exists in / / disk and the helper class needs / / to create a new one. @ Override public void onCreate (SQLiteDatabase _ db) {_ db.execSQL (DATABASE_CREATE);} "how to operate the database in Android" ends here. Thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

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