Java image interface development simple example-simple application of jbutton and events

Java image interface development example

Simple Application of jbutton and events, a small example of a calculator, the Code is as follows:

Import java. AWT. borderlayout;
Import java. AWT. gridlayout;
Import java. AWT. event. actionevent;
Import java. AWT. event. actionlistener;

Import javax. Swing. jbutton;
Import javax. Swing. jframe;
Import javax. Swing. jpanel;

/**
* Calculator instance
* @ Author Zuo Jie jdk5.0
*/
Public class calculatorframe extends jframe {
/**
*
*/
Private Static final long serialversionuid = 1l;

Public calculatorframe (){
Settitle ("Calculator ");
Calculatorpanel Panel = new calculatorpanel ();
Add (panel );
Pack ();
}

Public static void main (string [] ARGs ){
Calculatorframe frame = new calculatorframe ();
Frame. setdefaclocloseoperation (jframe. exit_on_close );
Frame. setvisible (true );
}
}

/**
* Create a display calculator panel
*/
Class calculatorpanel extends jpanel {
/**
*
*/
Private Static final long serialversionuid = 1l;

Private jbutton display; // used to display results
Private jpanel; // create a panel for displaying numbers and symbol buttons
Private double result; // used to store calculation results
Private string lastcommand; // record the clicked symbol
Private Boolean start; // The start flag.

Public calculatorpanel (){
Setlayout (New borderlayout ());
Result = 0;
Lastcommand = "= ";
Start = true;

// Add
Display = new jbutton ("0 ");
Display. setenabled (false );
Add (display, borderlayout. North );

// Create an event listening object
Actionlistener insert = new insertaction ();
Actionlistener command = new commandaction ();

// Panel for adding numbers and symbol buttons
Panel = new jpanel ();
Panel. setlayout (New gridlayout (4, 4); // set the panel layout to four rows and four columns
// Add digit and symbol buttons
Addbutton ("7", insert );
Addbutton ("8", insert );
Addbutton ("9", insert );
Addbutton ("/", command );

Addbutton ("4", insert );
Addbutton ("5", insert );
Addbutton ("6", insert );
Addbutton ("*", command );

Addbutton ("1", insert );
Addbutton ("2", insert );
Addbutton ("3", insert );
Addbutton ("-", command );

Addbutton ("0", insert );
Addbutton (".", insert );
Addbutton ("=", command );
Addbutton ("+", command );

Add (panel, borderlayout. center );
}

/**
* Used to set buttons and add corresponding listeners
*
* @ Param label
* @ Param listener: Corresponding event listening object
*
*/
Private void addbutton (string label, actionlistener listener ){
Jbutton button = new jbutton (Label );
Button. addactionlistener (listener );
Panel. Add (button );
}

/**
* Click the number button event to display the number and set the start flag to false;
*/
Private class insertaction implements actionlistener {
Public void actionreceivmed (actionevent event ){
String input = event. getactioncommand ();
If (start ){
Display. settext ("");
Start = false;
}
Display. settext (display. gettext () + input );
}
}

/**
* Click the symbol button event for calculation.
*/
Private class commandaction implements actionlistener {
Public void actionreceivmed (actionevent event ){
String command = event. getactioncommand ();
// If start is set to true, it indicates start. Then, click "-" to indicate a negative number.
If (start ){
If (command. Equals ("-")){
Display. settext (command );
Start = false;
} Else
Lastcommand = command;
} Else {// start is false for calculation.
Calculate (double. parsedouble (display. gettext ()));
Lastcommand = command;
Start = true;
}
}
}

/**
* The calculation method is more input data and symbols for calculation.
*
* @ Param X refers to the number entered.
*
*/
Public void calculate (Double X ){
If (lastcommand. Equals ("+ "))
Result + = X;
Else if (lastcommand. Equals ("-"))
Result-= X;
Else if (lastcommand. Equals ("*"))
Result * = X;
Else if (lastcommand. Equals ("/"))
Result/= X;
Else if (lastcommand. Equals ("= "))
Result = X;
Display. settext ("" + result );
}
}