A simple calculator using Java

There are two classes in total. It only completes the +,-, X, and merge operations.

The GUI is only usedAWTIt is very easy to understand.
Calculator. Java

Public class calculator {
Private string result = "0 ";
Private int op = 0, add = 1, sub = 2, mul = 3, DIV = 4;

Private double stringtodouble (string X ){
Double Y = double. parsedouble (X );
Return y;
}
Private void operate (string X ){
Double X1 = stringtodouble (X );
Double Y = stringtodouble (result );
Switch (OP ){
Case 0:
Result = X;
Break;
Case 1:
Result = string. valueof (Y + X1 );
Break;
Case 2:
Result = string. valueof (y-x1 );
Break;
Case 3:
Result = string. valueof (y * X1 );
Break;
Case 4:
If (x1! = 0 ){
Result = string. valueof (y/X1 );
} Else {
Result = "the divisor can" t be zero! ";
}

Java heaven

Break;
}
}

Public String opadd (string X ){
Operate (X );
OP = add;
Return result;
}
Public String opsubtract (string X ){
Operate (X );
OP = sub;
Return result;
}
Public String opmultiply (string X ){
Operate (X );
OP = Mul;
Return result;
}
Public String opdivide (string X ){
Operate (X );
OP = div;
Return result;
}
Public String opequals (string X ){
Operate (X );
OP = 0;
Return result;
}
Public void opclean (){
OP = 0;
Result = "0 ";
}
}

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Second
Calculatorgui. Java

Import java. AWT .*;
Import java. AWT. event .*;
Import java. util. eventobject;

Public class calculatorgui {
Private frame F;
Private panel P1, P2;

Java heaven

Private button B0, B1, B2, B3, B4, B5, B6, B7, B8, B9;
Private button bpoint, BADD, bdec, bmul, bdiv, bcal;
Private textfield TF;
Private string S, OP;
Private calculator Cal = new calculator ();
Private Boolean IFOP;

Public calculatorgui (){
F = new frame ("Calculator ");
P1 = new Panel ();
P2 = new Panel ();

B0 = new button ("0 ");
B1 = new button ("1 ");
B2 = new button ("2 ");
B3 = new button ("3 ");
B4 = new button ("4 ");
B5 = new button ("5 ");
B6 = new button ("6 ");
B7 = new button ("7 ");
B8 = new button ("8 ");
B9 = new button ("9 ");
Bpoint = new button (".");
BADD = new button ("+ ");
Bdec = new button ("-");
Bmul = new button ("*");
Bdiv = new button ("/");

Java heaven

Bcal = new button ("= ");

TF = new textfield (25 );
TF. seteditable (false );

}

Public void launchframe (){
F. setsize (220,160 );
F. setresizable (false );
F. addwindowlistener (New mywindowlistener ());
P1.setlayout (New flowlayout (flowlayout. Center ));
P1.add (TF );
F. Add (P1, borderlayout. North );
P2.setlayout (New gridlayout (4, 4 ));

B0.addactionlistener (New setlabeltext_actionlistener ());
B1.addactionlistener (New setlabeltext_actionlistener ());
B2.addactionlistener (New setlabeltext_actionlistener ());
B3.addactionlistener (New setlabeltext_actionlistener ());
B4.addactionlistener (New setlabeltext_actionlistener ());
B5.addactionlistener (New setlabeltext_actionlistener ());
B6.addactionlistener (New setlabeltext_actionlistener ());
B7.addactionlistener (New setlabeltext_actionlistener ());
B8.addactionlistener (New setlabeltext_actionlistener ());
B9.addactionlistener (New setlabeltext_actionlistener ());
Bpoint. addactionlistener (New setlabeltext_actionlistener ());
BADD. addactionlistener (New setoperator_actionlistener ());
Bdec. addactionlistener (New setoperator_actionlistener ());
Bmul. addactionlistener (New setoperator_actionlistener ());
Bdiv. addactionlistener (New setoperator_actionlistener ());
Bcal. addactionlistener (New setoperator_actionlistener ());

P2.add (B7 );
P2.add (B8 );
P2.add (B9 );
P2.add (BADD );
P2.add (B4 );
P2.add (B5 );
P2.add (B6 );
P2.add (bdec );
P2.add (B1 );
P2.add (B2 );
P2.add (B3 );
P2.add (bmul );
P2.add (B0 );
P2.add (bpoint );
P2.add (bcal );
P2.add (bdiv );
F. Add (P2, borderlayout. South );
F. setvisible (true );
}

Public void settextfieldtext_temp (){
If (Tf. gettext (). Length () <15 & (Tf. gettext (). indexof (".") =-1 |! S. Equals ("."))){
TF. settext (Tf. gettext () + S );
} Else {
TF. settext (Tf. gettext () + S). substring (0, 15 ));
}
}
Public void settextfieldtext (){

If (IFOP ){
IFOP = false;
TF. settext ("");
Settextfieldtext_temp ();
} Else {
Settextfieldtext_temp ();
}
}

Public static void main (string [] ARGs ){
Calculatorgui calculator = new calculatorgui ();
Calculator. launchframe ();
}

Class mywindowlistener extends windowadapter {
Public void windowclosing (windowevent e ){
System. Exit (0 );
}
}

Class setlabeltext_actionlistener implements actionlistener {
Public void actionreceivmed (actionevent e ){
Button tempb = (button) E. getsource ();
S = tempb. getlabel ();
Settextfieldtext ();
}
}

Class setoperator_actionlistener implements actionlistener {
Public void actionreceivmed (actionevent e ){
Button tempb = (button) E. getsource ();
OP = tempb. getlabel ();
If (op. Equals ("+ ")){
TF. settext (Cal. opadd (Tf. gettext (); Java heaven
IFOP = true;
} Else if (op. Equals ("-")){
TF. settext (Cal. opsubtract (Tf. gettext ()));
IFOP = true;
} Else if (op. Equals ("*")){
TF. settext (Cal. opmultiply (Tf. gettext ()));
IFOP = true;
} Else if (op. Equals ("/")){
TF. settext (Cal. opdivide (Tf. gettext ()));
IFOP = true;
} Else if (op. Equals ("= ")){
TF. settext (Cal. opequals (Tf. gettext ()));
IFOP = true;
}
}
}
}