java - 为什么我使用 result.getInt(2)/result.getInt(3) 和 result.getString(0)

Question

我有点困惑为什么在 RoutineRetrieved 函数中分配 ACTIVITYIMAGE 时使用 result.getInt(2) 并在分配 SLOT 时使用 result.getInt(3)...而在 ColourChange 函数中我使用 result。分配 DAY 时使用 getInt(0)。

我之前假设我指向的是 sqlite 数据库中的列。但现在我很困惑。谁能解释一下这些数字的含义？

例程检索函数:

    private void routineRetrieved() {

    Cursor result = myDb.retrieveRoutine(currentDay);                                               

    if (result.getCount() == 0) {                                                                   
        // Do nothing

    } else {                                                                                        

        while (result.moveToNext()) {                                                               
            int ActivityImage = result.getInt(2);                                                   
            int Slot = result.getInt(3);                                                            
            ImageView emptySlot = (ImageView) findViewById(Slot);                                   
            emptySlot.setImageResource(ActivityImage);                                              
        }
    }
}

颜色更改函数:

    private void colourChange() {
    Cursor result = myDb.checkColour();

    if (result.getCount() == 0) {                                                                   
        // Default colour remains

    } else {

        while (result.moveToNext()) {                                                               
            String day = result.getString(0);

            findViewById(getResources().getIdentifier(day + "button", "id", getPackageName()))      
                    .setBackgroundColor(getResources().getColor(R.color.colorSuccess));             
        }
    }
}

数据库.java

public class Database extends SQLiteOpenHelper

{
public static final String DATABASE_NAME = "application.db";
public static final int DATABASE_VERSION = 9;

// Table Name
public static final String RoutineTable = "Routines";

// Column Names
public static final String RoutineColumn1 = "DayOfWeek";
public static final String RoutineColumn2 = "Activity";
public static final String RoutineColumn3 = "Slot";

public Database(Context context)

{
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
}

@Override
public void onCreate(SQLiteDatabase db) {
    db.execSQL("CREATE TABLE `Routines` (`Routine` INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,`DayOfWeek`   TEXT NOT NULL,`Activity`    INTEGER NOT NULL, `Slot` INTEGER NOT NULL);");
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)

{
    onCreate(db);
}


public Cursor retrieveRoutine(String selectedDay) {                                                  WHERE DayOfWeek equals selectedDay and store this as result.


    SQLiteDatabase db = this.getWritableDatabase();
    Cursor result = db.rawQuery("select * from " + RoutineTable + " WHERE DayOfWeek = '" + selectedDay + "'", null);

    return result;
}

public boolean insertRoutine(int activityImage, String selectedDay, int activitySlot) {

    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put(RoutineColumn1,selectedDay);                                                  
    contentValues.put(RoutineColumn2,activityImage);                                                
    contentValues.put(RoutineColumn3,activitySlot);                                                 
    long result = db.insert(RoutineTable, null, contentValues);                                     

    if(result == -1)                                                                                
        return false;
    else
        return true;
}

public Cursor checkColour() {                                                                      

    SQLiteDatabase db = this.getWritableDatabase();
    Cursor result = db.rawQuery("SELECT DayOfWeek FROM " + RoutineTable + " GROUP BY DayOfWeek", null);

    return result;
}

Answer 1

方法 getInt 和 getString 中的数字参数是您想要获取的列的索引，从 0 开始，相对于您的查询已经完成了。

您有 2 个不同的查询。在 checkColour() 方法中，您有以下查询，该查询只有一个字段:

"SELECT DayOfWeek FROM " + RoutineTable + " GROUP BY DayOfWeek"

所以，当你打电话

Cursor result = myDb.retrieveRoutine(currentDay);     
String fieldValue = result.getString(0);

fieldValue 将具有查询的第一个字段的值，在本例中为 DayOfWeek

在另一个查询中也是如此，即表 Routines 的 SELECT *。在本例中，索引指的是 CREATE TABLE 语句中的字段位置。