Question

i’m making a chart which contain x and y value from sqlite.

my code is like this :

   Double a, b;

       notesCursor.moveToFirst();
   do {
       a = notesCursor.getDouble(notesCursor.getColumnIndex(DbAdapter.KEY_ROWID));
       b = notesCursor.getDouble(notesCursor.getColumnIndex(DbAdapter.KEY_RESULT));  
       mCurrentSeries.add(a, b);
   }while(notesCursor.moveToNext());

when i didn’t insert any x y value to my sqlite, the errors message came out… i want to add some code which when even i didn’t insert any x y value to my database, the chart will come out with 0, 0 value..

i’ve been making a code like this :

Double a, b;
   if(a==null && b==null){
       mCurrentSeries.add(0.0, 0.0);
   }
   else{      
       notesCursor.moveToFirst();
   do {
       a = notesCursor.getDouble(notesCursor.getColumnIndex(DbAdapter.KEY_ROWID));
       b = notesCursor.getDouble(notesCursor.getColumnIndex(DbAdapter.KEY_RESULT));  
       mCurrentSeries.add(a, b);
   }while(notesCursor.moveToNext());
   }

but i can’t make it work, anyone can help me to solve this problem? thank you

Answer 1

Your new code does not guarantee that a and b will be not null when passed to the mCurrentSeries.add method:

import java.util.HashMap;

import java.util.Map;

public class C {
Double a, b;
Map mCurrentSeries = new HashMap();
NotesCursor notesCursor = new NotesCursor();

public void yourMethod() {
    if (a == null && b == null) {
        mCurrentSeries.put(0.0, 0.0);
    } else {
        // notesCursor.moveToFirst();
        do {
            a = notesCursor.getDouble();
            b = notesCursor.getDouble();
            mCurrentSeries.put(a, b);
        } while (notesCursor.moveToNext());
    }
}

private static class NotesCursor {
    boolean b = false;

    public Double getDouble() {
        return null;
    }

    public boolean moveToNext() {
        return !b;
    }
}

public static void main(String... args) {
    C c = new C();
    c.yourMethod();
    System.out.println("a="+c.a);
    System.out.println("b="+c.b);
}

}