Skip to main content

Featured Post

How to use Tabs in ASP.NET CORE

I want to show Components in a tabs , so first of all create few components. In this project we have three components, First View Component  public class AllViewComponent : ViewComponent     {         private readonly UserManager<ApplicationUser> _userManager;         public AllViewComponent(UserManager<ApplicationUser> userManager)         {             _userManager = userManager;         }         public async Task<IViewComponentResult> InvokeAsync()         {             List<StudentViewModel> allUsers = new List<StudentViewModel>();             var items = await _userManager.Users.ToListAsync();             foreach (var item in items)             {                 allUsers.Add(new StudentViewModel {Id=item.Id, EnrollmentNo = item.EnrollmentNo, FatherName = item.FatherName, Name = item.Name, Age = item.Age, Birthdate = item.Birthdate, Address = item.Address, Gender = item.Gender, Email = item.Email });             }            

How to Add Functionality to NetBeans GUI: Java Programming

Programmer can know, to add graphical components in a frame and how to set their properties. But doing much is not sufficient in java programming, because the graphical controls that you add to frame can’t do anything on their own.

In other words, they have the look but not any feel. To add feel i.e. functionality or behaviour to them, you must also know about something called events and listeners. The three major players that add functionality to GUI are:

  • The Event: An event is an objects that gets generated when user does something such as mouse click, dragging, pressing a key on the keyboard etc.
  • Source of the Event: The component where the event has occurred, is the source of the event. For example, if a user clicks (the Event) on a Submit button then the source of this event is Submit button.
  • Event Listener: An event listener is attached to a component and contains the methods/functions that will be executed in response to an event. For example, if a user click on a button, then the buttons event listener will executed some code in response to this event.
    Listener Interface. An event Listener stores all the methods that it will implement in response to events, inside the listener interface. So, you can say that a listener interface stores all event-response-methods or event-handler methods of an event listener.

Commonly used Events and Listeners.


  • ActionEvents: of type ActionListener used to gets activated when the user performs an action with a button or other components. Usually, a user invokes the button by clicking over it. However, the user can also invoke a button action tabbing to the button and pressing the Enter key.
  • ItemEvent of type ItemListener used to gets activated when the selected item in a list control, such as a combo box or list box, is changed.
  • AdjustmentEvent of type AdgustListener used to gets activated when the user drags or moves knob of a scroll bar.
  • ChangeEvent of type ChangeListener used to gets active when the properties of a slider change.
  • KeyEvents of type KeyListener used to gets activate when the user press a key on the keyboard. You can use this event to watch for specific keystrokes entered by the user.
  • ListSelection of type ListSelectionListener used to get activated when an item is selected/deselected from list (JList).
  • MouseEvent of type MouseEventListener used to gets activated when the user does something with the mouse, such as clicks one of the buttons, drags the mouse, or simply moves over another objects.
  • FocusEvent of type FocusEventListener used to gets activated when a components receives or lose focus. Focus is ability to receive input, e.g., you can select from a list box only when it has focus, you can type in a text field only if it has focus.  


Each of the listeners listed above have multiple methods stored in their listener interfaces to respond to different type of events. You are armed with some basic knowledge of GUI functioning in Java so in further articles i will let you know about to create a GUI application using NetBeans.

Comments

Popular Post

Polynomial representation using Linked List for Data Structure in 'C'

Polynomial representation using Linked List The linked list can be used to represent a polynomial of any degree. Simply the information field is changed according to the number of variables used in the polynomial. If a single variable is used in the polynomial the information field of the node contains two parts: one for coefficient of variable and the other for degree of variable. Let us consider an example to represent a polynomial using linked list as follows: Polynomial:      3x 3 -4x 2 +2x-9 Linked List: In the above linked list, the external pointer ‘ROOT’ point to the first node of the linked list. The first node of the linked list contains the information about the variable with the highest degree. The first node points to the next node with next lowest degree of the variable. Representation of a polynomial using the linked list is beneficial when the operations on the polynomial like addition and subtractions are performed. The resulting polynomial can also

How to use Tabs in ASP.NET CORE

I want to show Components in a tabs , so first of all create few components. In this project we have three components, First View Component  public class AllViewComponent : ViewComponent     {         private readonly UserManager<ApplicationUser> _userManager;         public AllViewComponent(UserManager<ApplicationUser> userManager)         {             _userManager = userManager;         }         public async Task<IViewComponentResult> InvokeAsync()         {             List<StudentViewModel> allUsers = new List<StudentViewModel>();             var items = await _userManager.Users.ToListAsync();             foreach (var item in items)             {                 allUsers.Add(new StudentViewModel {Id=item.Id, EnrollmentNo = item.EnrollmentNo, FatherName = item.FatherName, Name = item.Name, Age = item.Age, Birthdate = item.Birthdate, Address = item.Address, Gender = item.Gender, Email = item.Email });             }            

Memory representation of Linked List Data Structures in C Language

                                 Memory representation of Linked List              In memory the linked list is stored in scattered cells (locations).The memory for each node is allocated dynamically means as and when required. So the Linked List can increase as per the user wish and the size is not fixed, it can vary.                Suppose first node of linked list is allocated with an address 1008. Its graphical representation looks like the figure shown below:       Suppose next node is allocated at an address 506, so the list becomes,   Suppose next node is allocated with an address with an address 10,s the list become, The other way to represent the linked list is as shown below:  In the above representation the data stored in the linked list is “INDIA”, the information part of each node contains one character. The external pointer root points to first node’s address 1005. The link part of the node containing information I contains 1007, the address of