Event Handling in java

Event: The act of changing the state of one object to another is called event.The java.awt.event package provides some action  or key events like clicking the button,press the key etc.Events are supported by a number of Java packages, like java.util, java.awt and java.awt.event.Some event classes that provide some action or key press events that are:

• Action Event:-Action listener generated when any button is pressed.It performs a particular action.The syntax for action listener is:

private void jButtonActionPerformed(java.awt.event.ActionEvent evt)

 {  

//Code on which action is to be performed

 }

• Mouse Event:-Mouse listener generated when mouse is dragged,moved or released.The syntax for using a mouse listener is:

private void jTextFieldMouseClicked(java.awt.event.MouseEvent evt) {

        //code on which mouse event is to be performed

    }

• Key Event:-Key listener generated when key is pressed from keyboard.The syntax for using key listener event is:

private void jTextFieldKeyTyped(java.awt.event.KeyEvent evt)

 {                                     

  //Code on which key event is to be performed

  }

• Focus Event:-Focus listener generated when the cursor gains or looses the focus.The syntax for using focus event listener is

private void jTextFieldFocusLost(java.awt.event.FocusEvent evt) 

{

//Code on which focus event listener is to be performed.

 }

• Mouse Motion Event:-Mouse wheel listener is generated when mouse  is moved.The syntax for this event is:

private void jTextFieldMouseMoved(java.awt.event.MouseEvent evt)

 {

  // code on which action is to be performed

    }

To apply any of the above event on your code,you just need to right click on the control where you want to perform the action then go to event and select which event listener you want to select,these events can be performed on Text fields,Radio buttons,Password fields,lists,combo box etc.