C#

FJJCENTU wrote:

I see in near every example using threads that the method to execute in the starting of the threads belong to a different class

class Foo
{
   List<string> strings = new List<string>();

   void StartThreads()
   {
      Thread t1 = new Thread(Thread1Execute);
      Thread t2 = new Thread(Thread2Execute);
      t1.Start();
      t2.Start();
   }  

   void Thread1Execute()
   {
      // this can access strings variable
   }

   void Thread2Execute()
   {
      // this can access strings variable
   }
}

FJJCENTU wrote:

in such case I don`t understand to use Lock(this) or Monitor(this), I`m not sinchronizing all the class but only a method.

1. The object should not be modifiable without your knowledge. See the following code

   class Foo
   {
       public object locker = new object();
   }

   In this any one can modify the locker object from outside of class Foo without your knowledge. This is dangerous.
2. All the threads that require this object should be able to access the locker object.

class Foo
{
   List<string> strings = new List<string>();
   readonly object locker = new object();

   void StartThreads()
   {
      Thread t1 = new Thread(Thread1Execute);
      Thread t2 = new Thread(Thread2Execute);
      t1.Start();
      t2.Start();
   }  

   void Thread1Execute()
   {
       lock(locker)
       {
           // your code
       }
   }

   void Thread2Execute()
   {
       lock(locker)
       {
           // your code
       }
   }
}

ComboBox cc = new ComboBox();
cc.DataSource = dt;           //dt represents Datatable filled with data from database.
cc.DisplayMember = "xx";      // xx is a columnname which will be shown to user. Usually Name
cc.ValueMember = "yy";       //yy is the columnname which will be used internally. Usually ID.
cc.SelectedValue = "value";  // assign the selected yy value from the database.

DataTable dt = ds.Tables[0];  // Grab by index, with 0 being the first
DataTable dt = ds.Tables["MyTableName"]; // Grab it by name, based on how it's defined in the XML