//
// another example of the Java AWT.  see class definition and main
//      method for details.
// compare to SwitchedButtonAlt.java, which implements much the same
//      behavior with different techniques.
//
import java.awt.* ;
import java.awt.event.* ;

//
// a SwitchedButton object represents a main button plus a "switch"
//      button that toggles the main button's behavior between 
//      "not listening" and "listening", using addActionListener() and
//      removeActionListener().
//
// this class extends Container because that's an easy way to group
//      the two buttons and specify a layout for them.
//
class SwitchedButton extends Container implements ActionListener {

        Button mainButton ;
        String mainLabel ;
        Button switchButton ;
        boolean buttonOn = false ;

        // constructor:
        //      s is the label for the main button.
        SwitchedButton(String s) {

                super() ;       
                mainLabel = s ;

                // specify desired layout (buttons side by side).
                setLayout(new GridLayout(1, 2)) ;

                // make main button and add to container.
                mainButton = new Button(s + " (off)") ;
                add(mainButton) ;

                // make "switch" button and add to container.  
                switchButton = new Button("Switch for " + s) ;
                add(switchButton) ;

                // set up to process button-press events for switch.
                switchButton.addActionListener(this) ;
        }

        // process button-press events:
        //      for "switch" button, toggle main button off and on.
        //      for main button, write message to standard output.
        public void actionPerformed(ActionEvent e) {

                Object src = e.getSource() ;
                if (src == mainButton) {
                        System.out.println(mainLabel + " pressed") ;
                }
                else if (src == switchButton) {
                        String newlbl ;
                        buttonOn = !buttonOn ;
                        // if switch is off now, stop listening for
                        //      events from main button.
                        if (!buttonOn) {
                                mainButton.removeActionListener(this) ;
                                newlbl = mainLabel + " (off)" ;
                        }
                        // if switch is on now, start listening.
                        else {
                                mainButton.addActionListener(this) ;
                                newlbl = mainLabel + " (on)" ;
                        }
                        // relabel button
                        mainButton.setLabel(newlbl) ; 
                }
        }

        //
        // ---- main method --------------------------------------------
        //
        // command-line argument is N, number of button/switch pairs
        //      to create (default 4).
        //
        public static void main(String[] args) {

                int num = 4 ;
                if (args.length > 0) 
                        num = Integer.parseInt(args[0]) ;

                // frame with title
                CloseableFrame f = 
                        new CloseableFrame("SwitchedButtonAlt") ;

                // set up to display pairs of buttons in a (vertical)
                //       column.
                f.setLayout(new GridLayout(num, 1)) ;

                // create and add buttons b1 .. bN.
                for (int i = 0 ; i < num ; i++)
                        f.add(new SwitchedButton("b" + (i+1) )) ;

                // set minimum size needed to hold everything, and
                //      display.
                f.pack() ;
                f.show() ;
        }
}