Android: transform each column of a cursor into a String array

Question

let's say if this is my code

Cursor mCursor = dbAdapter.getAllTitles(); //returns results from 3 columns, eg column1, column2, column3

is there anyway I can assign the values from column1 to 1 string array, column2 to another and so on? perhaps like this

String[] getColumn1 = mCursor.dataFrom("column1");
String[] getColumn2 = mCursor.dataFrom("column2");
String[] getColumn3 = mCursor.dataFrom("column3");

examples i see to achieve the same result as above involves iterating through the values and put them into the respective array. too much resource consuming, no? then it's better to make separate sql query for each columns, no?

What is your Schema? and Why do you need to assign column values to an array of Strings? — Rajdeep Dua
– Rajdeep Dua, Commented Jan 20, 2012 at 9:10
what do u mean by Schema? And let's just say I need to manage to assign column values to an array of Strings — imin
– imin, Commented Jan 20, 2012 at 9:36

Community · Accepted Answer · 2017-05-23 11:53:59Z

5

I found the answer posted by Dyonisos is correct, except I would change this line in the for loop:

for(mCursor.moveToFirst(); mCursor.moveToNext(); mCursor.isAfterLast())

to this:

for(cursor.moveToFirst(); !cursor.isAfterLast();cursor.moveToNext() )

As the middle statement is the one that checks whether to continue the loop. This may answer Liam W's question in the accepted answer's comments.

Disclaimer: I am aware this should've been a comment, but I don't have enough reputation to make one and this information might be useful to others who come looking for this information in the future =)

edited May 23, 2017 at 11:53

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answered Apr 1, 2014 at 13:57

hst

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Dyonisos · Accepted Answer · 2014-10-23 12:25:26Z

4

ArrayList<String> columnArray1 = new ArrayList<String>();
ArrayList<String> columnArray2 = new ArrayList<String>();
ArrayList<String> columnArray3 = new ArrayList<String>();
for(mCursor.moveToFirst(); mCursor.isAfterLast(); mCursor.moveToNext()) {
    columnArray1.add(mCursor.getString(COLUM_INDEX1));
    columnArray2.add(mCursor.getString(COLUM_INDEX2));
    columnArray3.add(mCursor.getString(COLUM_INDEX3));
}

Afterwards you can convert the ArrayList into a String array:

String[] colStrArr1 = (String[]) columnArray1.toArray(new String[columnArray1.size()]);

edited Oct 23, 2014 at 12:25

answered Jan 20, 2012 at 9:37

Dyonisos

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4 Comments

imin Over a year ago

this one converts it into ArrayList right.. how do I convert it to something that can be insert inside String[] getColumn for example?

Dyonisos Over a year ago

You can convert your ArrayList to a String array. E.g.: String[] colStrArray1 = (String []) columnArray1.toArray(new String [columnArray1.size()]);

Anupam Over a year ago

Hey Dyonisos, I'm trying to do the same thing, but columnArray1.add(mCursor.getString(COLUM_INDEX1)); COLUMN_INDEX is giving me error to change this into string. Can you please guide me through this.

Liam W Over a year ago

Sorry to bump an old question & answer, but this works with one snag - the first one is always ignored. I don't know if it's an issue with the query selection, or this system...

Fletcher Johns · Accepted Answer · 2014-06-07 03:04:40Z

0

Another way to do this without the use of ArrayList:

final int size = mCursor.getCount();
mArray1 = new String[size];
mArray2 = new String[size];
mArray3 = new String[size];

if (mCursor.moveToFirst) {
    int i = 0;
    do {
        mArray1[i] = mCursor.getString(COLUMN_INDEX_1);
        mArray2[i] = mCursor.getString(COLUMN_INDEX_2);
        mArray3[i] = mCursor.getString(COLUMN_INDEX_3);
        i++;
    } while (mCursor.moveToNext());
}

This will also work for arrays of primitives

edited Jun 7, 2014 at 3:04

answered Jun 7, 2014 at 1:37

Fletcher Johns

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Comments

Jens-Joris Decorte · Accepted Answer · 2014-08-01 09:54:18Z

0

Actually, it's easy to convert cursor into arrays. Use this method:

private void initializeArrays(Cursor c) {
    collumn1 = new String[c.getCount()];
    collumn2 = new String[c.getCount()];
    for(c.moveToFirst(); !c.isAfterLast(); c.moveToNext()) {
        Array.set(collumn1, c.getPosition(), c.getString(c.getColumnIndex(""collum1")));
        Array.set(collumn2, c.getPosition(), c.getString(c.getColumnIndex("collumn2")));
    }
}

answered Aug 1, 2014 at 9:54

Jens-Joris Decorte

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Community · Accepted Answer · 2017-05-23 12:25:19Z

0

As several other answers have said, I agree that dyonisos's answer is basically correct, but I think that a simpler way (and safer way) to implement the loop is a while loop like this:

while (mcursor.moveToNext()){
            try {
                columnArray1.add(cursor.getString(1));
                columnArray2.add(cursor.getString(2));
                columnArray3.add(cursor.getString(3));
                 ...
            }catch(Exception e) {
                Log.d("error",e.toString());
            }
        }

and then one can convert the arrays as in the previously cited answer.

String[] colStrArr1 = (String[]) columnArray1.toArray(new String[columnArray1.size()]);

edited May 23, 2017 at 12:25

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answered Nov 12, 2015 at 15:32

iman kazemayni

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