displaying the value of a particular row

Question

I am trying to display value of a particular row in android to check if a particular updation. Can I made it successful or not? But as the return type is cursor I don't know how to fetch it. So pls help me.

public Cursor getData(int id) {
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor res = db.rawQuery("select * from calls where id=" + id + "", null);
    return res;
}

Answer 1

Try this...

ArrayList<HashMap<String, String>> dataList = new ArrayList<>();

call your method to get data as arraylist of hashmap

dataList.addAll(loginDataBaseAdapter.getData(id));

or

dataList = loginDataBaseAdapter.getData(id);

in db_class

public ArrayList<HashMap<String, String>> getData(String id) {
  ArrayList<HashMap<String, String>> returnArray = new ArrayList<>();
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor res = db.rawQuery("select * from calls where id=" + id + "", null);

if (res != null && res.getCount() > 0) {
 if (res.moveToLast()) {
    do {
       HashMap<String, String> getdatamap = new HashMap<String, String>();
         getdatamap.put("KEY_ONE", res.getString(1));
         getdatamap.put("KEY_TWO, res.getString(2));

         returnArray.add(getdatamap);
       }while (res.moveToPrevious());
   }
 }
 res.close();
 return returnArray;
}

Now you can use the values in arraylist to make your view

Answer 2

You can follow the below code:

SQLiteDatabase db = this.getReadableDatabase();
Cursor res = db.rawQuery("select * from calls where id=" + id + "", null);
if (res != null) {
    res.moveToFirst();
}
String firstColumnValue = res.getString(0);
String secondColumnValue = res.getString(1);

And close the database after retrieving values:

db.close();

If you want to get column value by its name, then use the following code:

String value = res.getColumnIndex("column_name");

Answer 3

Get row value as a String. Then return string value.

public String getData(int id) {
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor res = db.rawQuery("select * from calls where id=" + id + "", null);    
        if (res.getCount() > 0) {
            res.moveToFirst();
            String s = res.getString(res.getColumnIndex("id"));
return s;
}

Answer 4

There are two factors that need to be considered when retrieving data from a cursor; which row (position within the cursor) and then column and it's type.

To position the Cursor you use one of the Cursor's move methods. These are :-

• move, which moves the cursor relevant to it's current position.
• moveToFirst
• moveToLast
• moveToNext
• moveToPosition and
• moveToPrevious

All return true if the move could be performed otherwise false.

A cursor can be empty and have no rows, so movetoFirst would return false.

One of the more common usages is :-

while (cursor.moveToNext) {
    .... cursor action(s) here.
}

A Cursor will initially be positioned to before the first row i.e. it's position is -1 and can be set using moveToPosition(-1).

The Cursor's getPosition method will retrieve the current position, noting that the first row is position 0.

Column's in rows are accessed according to the offset (which column) and the Cursor's get???? (where ???? represents type) methods are used to retrieve the data from the row/column (there are other get.... methods e.g. getPosition as above). The methods for retrieving the data are:-

• getBlob (retrieves a byte array).
• getDouble
• getFloat
• getInt
• getLong
• getShort
• getString

All take a single parameter, an integer that is the column's offset within the cursor (which is not necessarily the offset in the table).

You can use any on any type of data, with the exception of blobs. An attempt to use any, except getBlob, on a BLOB will result in an exception.

However, the results, can vary e.g. if you use get, for example assuming column with offset 0 contains *rumplestilskin then :-

• cursor.getString(0) will return rumplestiltskin
• cursor.getDouble(0) will return 0 as a double.
• cursor.getInt(0) will return 0 as a float.
• .....

In short, you should use the appropriate get method, otherwise the results could be confusing.

Hard coding column column offsets, often results in issues therefore it is generally better to use column names in conjunction with the Cursor's getColumnIndex method. This takes a String, the column name, as a parameter and returns the offset of the column.

Applying the above to the question:-

Code that could be useful (i.e. it retrieves data) could be :-

    Cursor csr = db.getData(myid);
    while (csr.moveToNext) {
         long id_of_the_row = csr.getLong(csr.getColumnIndex(yourDatabaseHelperClass.id));
    }

Noting:-

• if (moveToFirst(myid)) { .... } could be considered more correct but assuming that just a single row exists bot moveToFirst and moveToNext, as coded, produce the same result.
• Assuming that the id column is an alias of the rowid, then rowid is stored as a long and should properly be extracted as a long.
• yourDatabaseHelperClass.id will not be correct, rather you would replace it with the class that extends SQLiteOpenHelper (the class that contains your getData method), it also assumes that variable id has public access.

Links that may be useful or of interest:-

• Cursor

• How flexible/restricive are SQLite column types?

  • (includes examples of how some of the Cursor get???? methods retrieve data)

• Are there any methods that assist with resolving common SQLite issues?