Tutorial 5

Input/Output GUI Elements

1. Drag a JCheckbox to the window.  Left-Mouse-Button double-click on it to change the text property to "Timer Control Sliders".  Right-Mouse-Button single-click on it, and then Change Variable Name... to "chkTimerControlSliders"
2. In the Source view of the JFrame, we will create a class that responds to the Timer object.  While we could put this all into an anonymous event listener, the code is complicated enough that a separate class is better.  Add the following to your SwingExampleFrame class (above main is a good place for it).
    public void actionPerformed(java.awt.event.ActionEvent evt) {
   
   // Each time the timer goes off the total number of seconds will be incremented
   // and the timer text field will be updated to display the total seconds elapsed.
   m_seconds++;
   timerEcho.setText(m_seconds + ": Seconds have passed");
   
   // If the ControlSliders check box is selected, then the horizontal and
   // vertical sliders will also be decremented.
   if(chkTimerControlSliders.isSelected()){
   hSliderBar.setValue(hSliderBar.getValue() - 1);
   vSliderBar.setValue(vSliderBar.getValue() - 1);
   }
   
   // When both sliders reach 0, the ControlSliders checkbox will be unselected.
   if((hSliderBar.getValue()==0) && (vSliderBar.getValue()==0))
   chkTimerControlSliders.setSelected(false);
   }
   }
3. Change the SwingExampleFrame's constructor so that it creates a Timer object, that will call the above code, like so:
    public SwingExampleFrame() {
   initComponents();
   // Creates a timer that will go off every 1000 ms.
   javax.swing.Timer t = new javax.swing.Timer(1000, new TimerListener());
   t.start(); // Start the timer
   }

• In the Visual Studio project window, click
  1. Build >> Build Solution
  2. Debug >> Start to run

  
  Figure 5.1 - Application Window