JAVA Case Tutorial (1)

Tutorials//************************************


//A simple Java program


//function is to demonstrate a small window with the ability to read and write files.


//@author Gaogao


//@date 2004-11-04


// ************************************





// ************************************


//introduction of GUI and GUI event handling classes, and I/O managed classes


// ************************************


import java.awt.*;


import java.awt.event.*;


import java.io.*;





// ************************************


//Testone, a Demo menu and button application


//program.


// ************************************


public class Testone extends Frame implements ActionListener {


//inherit from frame, implement ActionListener interface


//frame is a form of frame class, ActionListener is an event interface that implements his


//Can do event handling.





// ************************************


//declaring variables


// ************************************


//Menu control


Private MenuBar MB;


private Menu Mfile;


private MenuItem miload;


private MenuItem Misave;


private MenuItem Miexit;


//Button


private TextArea TextArea;


//Disk Management


private file file;


//FileName


public static final String filename_str = "Love.TXT";


// ************************************


//Construction


// ************************************


public Testone () {


init ();





Putobjectstomyframe ();


addlistenerstoobjects ();


Setthewindow ();


}


// ************************************


//Allocating object memory


// ************************************


private void init () {


MB = new MenuBar ();


mfile = new Menu ("File");


miload = new MenuItem ("Load");


misave = new MenuItem ("Save");


miexit = new MenuItem ("Exit");





TextArea = new TextArea ("");


}





// ************************************


//Install parts to window


// ************************************


private void Putobjectstomyframe () {


Setmenubar (MB);


Mb.add (Mfile);


Mfile.add (miload);


Mfile.add (Misave);


Mfile.add (miexit);


Add (TextArea);


}





// ************************************


//Settings window


// ************************************


private void Setthewindow () {


this.setsize (400,300);


this.show ();


Addwindowlistener (


New Windowadapter () {


public void windowclosing (WindowEvent we)


{


system.exit (0);


}


}


);


}


// ************************************


//Set Event listener


// ************************************


private void Addlistenerstoobjects () {


Miload.addactionlistener (this)//the event listener miload This menu is placed in the instance of this window


Misave.addactionlistener (this);


Miexit.addactionlistener (this);





}


// ************************************


//Event listeners (this is the case of this class) after hearing the event


//Call. This method is an abstract
in the ActionListener interface

//Method implementation.


// ************************************


public void actionperformed (ActionEvent ae) {


if (ae.getsource () = = Miload)


{





//


System.out.println ("Loading");


DataInputStream Dis;





try {


file = new file (FILENAME_STR);


dis = new DataInputStream (new FileInputStream (file));


Textarea.settext ("");


////No Java doc documents are not written. To be perfected.


Dis.close ();


}


catch (Exception ex)


{


System.out.println (Ex.getmessage ());


}














}


Else if (ae.getsource () = = Misave)


{


//


System.out.println ("Saving");


DataOutputStream dos;


try {


file = new file (FILENAME_STR);


dos = new DataOutputStream (new FileOutputStream (file));


int i = 0;


String temp = Textarea.gettext ();


while (I < temp.length ())


{


Dos.writechar (Temp.charat (i++));


}





Dos.close ();


}


catch (Exception ex)


{


System.out.println (Ex.getmessage ());


}








}


Else if (ae.getsource () = = Miexit)


{


//Exit Application


System.out.println ("Exit");


system.exit (0);


}





}


// ************************************


//Program entry.


// ************************************


public static void Main (string[] args) {


new Testone ();


}


}