The cursor class for Android notes

About Cursor

When you understand and use the Android cursor, you must first know a few things about the cursor:

• The Cursor is a collection of each row.
• Use Movetofirst () to locate the first row.
• You must know the name of each column.
• You must know the data type of each column.
• The Cursor is a random data source.
• All data is obtained by subscript.

important methods for Cursor :

• Close () Closes the cursor, freeing the resource
• Copystringtobuffer (int columnindex, Chararraybuffer buffer) retrieves the text of the requested column in the buffer, storing it
• getColumnCount () returns the total number of all columns
• Getcolumnindex (String columnName) returns the name of the specified column if there is no return-1
• Getcolumnindexorthrow (String columnName) returns the specified column name from zero, and throws a illegalargumentexception exception if it does not exist.
• getColumnName (int columnindex) returns the column name from the given index
• Getcolumnnames () returns the column name of a string array
• GetCount () returns the number of rows in the cursor
• Movetofirst () Move cursor to first line
• Movetolast () Move the cursor to the last line
• MoveToNext () Move the cursor to the next line
• movetoposition (int position) moves the cursor to an absolute position
• Movetoprevious () Move cursor to previous line

Determine if the cursor is empty

if false ) {// empty cursorreturn;}

Access the Cursor's subscript to get the data

int Namecolumnindex = cur.getcolumnindex (people.name); String name = cur.getstring (namecolumnindex);

Now let's see how we loop the Cursor out of the data we need.

while(Cur.movetonext ()) { // cursor moved successfully // pull data out }

When Cur.movetonext () is false, it jumps out of the loop, that is, the Cursor data loop is complete.

If you prefer using a for loop instead of a while loop, you can use the few methods that Google provides:

• Isbeforefirst () returns whether the cursor points to the position of the previous first row
• Isafterlast () returns whether the cursor points to the position of the last row
• IsClosed () Returns true to indicate that the game has been marked off

With the above method, you can remove the data

For! cur.isafterlast (); Cur.movetonext ()) {    int namecolumn  = cur.getcolumnindex (People.name);      int phonecolumn = cur.getcolumnindex (People.number);     String  Name = cur.getstring (NameColumn);      string phonenumber =  cur.getstring (Phonecolumn); }

Done

The cursor class for Android notes