What is Adapter Pattern and how it is implementated in .net?

Adapter Pattern:

This pattern is comes under àstructural pattern

Structural Pattern makes à grouping objects(related objects)together with good standarazation.

Example:

SqlDataAdapter Fill() -à Method. Which has their own implementation(with one more interfaceà interface IDataAdapter).

Yes,

public interface IDataAdapter

{

int Fill(DataSet dataSet);  // by default : virtual, public

}

Based on the type of DataAdapteràSqlDataAdapter,OracleDataAdapter…are implements DbDataAdapter.

Base on the type of DataAdapter(SqlDataAdapter,OracleDatapter..)

DbDataAdapter provides the underlaing implementation as per the DataAdapter.

Here

public interface IDataAdapter

{

int Fill(DataSet dataSet);  // by default : virtual, public ,abstract *****

}

Which

Class DbDataAdapter : DataAdapter

{

public override int Fill(DataSet dataSet);

}

SqlDataAdapter : DbDataAdapter

OracleDataAdapter : DbDataAdapter

As well we have SqlDataAdapter,OracleDataAdapter…ect these all are derived from DbDataAdapter class.

Which(DbDataAdapter) makes the Fill() method to their apporiate Sql/Oracle/oldedb—Adapter implementation. 

Note: as per the type of Adapter -->the relavent object is not created(like creation pattern). instead of creation the relavent implementation is called by DbDataAdapter abstract class(structural pattern).

So

SqlConnection con = new SqlConnection("uid=sa;pwd=zolt123$;database=wcfdb");

SqlDataAdapter da = new SqlDataAdapter("select * from emp", con);
DataSet ds = new DataSet();da.Fill(ds);
dataGridView1.DataSource = ds.Tables[0];

da.Fill(ds)………………>(DbDataAdapter).Fill()   // here da is SqlDataAdapter.

as well

OleDbConnection con = new OleDbConnection("uid=sa;pwd=zolt123$;database=wcfdb");
OleDbDataAdapter da = new OleDbDataAdapter("select * from emp", con);
DataSet ds = new DataSet();da.Fill(ds);
dataGridView1.DataSource = ds.Tables[0];

da.Fill(ds)………………>(DbDataAdapter).Fill()  // here da is OracleDataAdapter.

----Adapter pattern makes objects grouping together. with same programming style.

Fill()

Fill()method implementation is different from Adapter to Adapter(sql/oracle/oledb).so making good standarazation microsoft defines IDataAdatper interface and DataAdapter classes.

DataAdapter :IDataAdapter
and
DbDataAdapter: DataAdapter
and
SqlDataAdapter : DbDataAdapter

SqlDataAdapter implementation inside-à DbDataAdapter(not in SqldataAdapter).

OracleDataAdapter implementation inside-àDbDataAdapter(not in OracledataAdapter).

we can say this implementation as -->Abstraction. why because based on the type of dataadapter to working with their apporiate mdf, ldf files to fill dataset.

Open() and Close() relavent-to methods---SqlConnection has their own implementation.----IDbConnection not like Fill() method.