Suppose you want to place your cursor in a text field at a desired position. Your text field has a display size of 20 characters and a data size of 50 characters. If you enter all 50 characters, it's tedious to try to see the entire text. Rather than lose focus of the text field, you can program it so you see the starting characters rather than what you keyed-in at the end. The following line of code accomplishes this:
//Creation of the textfield
TextField textField = new TextField(50);
//Code to be inserted when focus lost happens on the textfield
will set the cursor's position to the beginning of the text field. If you desire, you can place it at any character place you want to.