以下是一个使用Android Room进行高级查询、列表和多条件查询的示例解决方法:
dependencies {
def room_version = "2.3.0"
implementation "androidx.room:room-runtime:$room_version"
annotationProcessor "androidx.room:room-compiler:$room_version"
}
@Entity(tableName = "users")
public class User {
@PrimaryKey
public int id;
public String name;
public int age;
// 添加其他字段和方法
}
@Dao
public interface UserDao {
@Query("SELECT * FROM users")
List getAllUsers();
@Query("SELECT * FROM users WHERE age > :minAge")
List getUsersOlderThan(int minAge);
@Query("SELECT * FROM users WHERE name LIKE '%' || :name || '%'")
List getUsersWithName(String name);
// 添加其他查询方法
}
@Database(entities = {User.class}, version = 1)
public abstract class AppDatabase extends RoomDatabase {
public abstract UserDao userDao();
private static AppDatabase INSTANCE;
public static AppDatabase getInstance(Context context) {
if (INSTANCE == null) {
INSTANCE = Room.databaseBuilder(context.getApplicationContext(), AppDatabase.class, "app_database")
.build();
}
return INSTANCE;
}
}
AppDatabase db = AppDatabase.getInstance(this);
// 获取所有用户
List allUsers = db.userDao().getAllUsers();
// 获取年龄大于18的用户
List olderUsers = db.userDao().getUsersOlderThan(18);
// 获取名字包含"John"的用户
List johnUsers = db.userDao().getUsersWithName("John");
这样,你就可以使用Android Room进行高级查询、列表和多条件查询了。请根据你的实际需求修改实体类、数据访问对象和数据库类中的代码,以适应你的应用程序。