在 Android Studio 中结合使用 SQLite 数据库实现简单的注册和登录功能

```java
   public class DBHelper extends SQLiteOpenHelper {
       private static final String DATABASE_NAME = "mydatabase.db";
       private static final int DATABASE_VERSION = 1;
 
       public DBHelper(Context context) {
           super(context, DATABASE_NAME, null, DATABASE_VERSION);
       }
 
       @Override
       public void onCreate(SQLiteDatabase db) {
           String createTable = "CREATE TABLE users (id INTEGER PRIMARY KEY AUTOINCREMENT, username TEXT, password TEXT)";
           db.execSQL(createTable);
       }
 
       @Override
       public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
           db.execSQL("DROP TABLE IF EXISTS users");
           onCreate(db);
       }
   }
   ```

```java
   public void registerUser(String username, String password) {
       SQLiteDatabase db = getWritableDatabase();
       ContentValues values = new ContentValues();
       values.put("username", username);
       values.put("password", password);
       db.insert("users", null, values);
       db.close();
   }
   ```

```java
   public boolean loginUser(String username, String password) {
       SQLiteDatabase db = getReadableDatabase();
       Cursor cursor = db.rawQuery("SELECT * FROM users WHERE username=? AND password=?", new String[]{username, password});
       boolean result = cursor.getCount() > 0;
       cursor.close();
       db.close();
       return result;
   }
   ```

```xml
   
   
   ```