Cómo elaborar una calculadora.

1. Java Visual Basic
Sin interfaz
import javax.swing.*; public class Menu { public static void
main(String []agrs) { int op=0; double n1,n2,s,m,d,r; do{
op=Integer.parseInt(JOptionPane.showInputDialog("nCalculadoran
"+ "************n"+ "[1] SUMARn"+ "[2] RESTARn"+ "[3]
MULTIPLICARn"+ "[4] DIVIDIRn"+ "[5] SALIRn"+ "Ingresa una
opcion:")); switch(op) { case 1:
n1=Double.parseDouble(JOptionPane.showInputDialog("Ingrese
numero 1"));
n2=Double.parseDouble(JOptionPane.showInputDialog("Ingrese
numero 2")); s=n1+n2; JOptionPane.showMessageDialog(null,"La
suma es:"+s); break; case 2:
n1=Double.parseDouble(JOptionPane.showInputDialog("Ingrese
numero 1"));
n2=Double.parseDouble(JOptionPane.showInputDialog("Ingrese
numero 2")); r=n1-n2; JOptionPane.showMessageDialog(null,"La
resta es:"+r); break; case 3:
n1=Double.parseDouble(JOptionPane.showInputDialog("Ingrese
numero 1"));
n2=Double.parseDouble(JOptionPane.showInputDialog("Ingrese
numero 2")); m=n1*n2; JOptionPane.showMessageDialog(null,"La
multiplicacion es:"+m); break; case 4:
n1=Double.parseDouble(JOptionPane.showInputDialog("Ingrese
numero 1"));
n2=Double.parseDouble(JOptionPane.showInputDialog("Ingrese
numero 2")); d=n1/n2; JOptionPane.showMessageDialog(null,"La
division es:"+d); break; } }while(op!=5); } }
Private Sub Command1_Click()
Text3.Text = Val(Text1.Text) + Val(Text2.Text)
End Sub
Private Sub Command2_Click()
Text3.Text = Val(Text1.Text) - Val(Text2.Text)
End Sub
Private Sub Command3_Click()
Text3.Text = Val(Text1.Text) * Val(Text2.Text)
End Sub
Private Sub Command4_Click()
Text3.Text = Val(Text1.Text) / Val(Text2.Text)
End Sub
Private Sub Command5_Click()
Text1.Text = ""
Text2.Text = ""
Text3.Text = ""

2. Calculadora con Interfaz en Java- CLASE MAIN… Código completo
import java.util.logging.Level; import
java.util.logging.Logger; import javax.swing.UIManager; import
javax.swing.UnsupportedLookAndFeelException; public class
CalculadoraGUI { public static void main(String[] args) {
String ax = System.getProperty("os.name"); //variable que toma
el nombre del sistema operativo que se tenga instalado
if(ax.equals("Windows 7") || ax.equals("Windows")){//si es un
sistema windows se aplica el skin que tiene java para windows
try {
UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.Wind
owsLookAndFeel"); interfaz w = new interfaz(); // TODO code
application logic here } catch (ClassNotFoundException ex) {
Logger.getLogger(interfaz.class.getName()).log(Level.SEVERE,
null, ex); } catch (InstantiationException ex) {
Logger.getLogger(interfaz.class.getName()).log(Level.SEVERE,
null, ex); } catch (IllegalAccessException ex) {
Logger.getLogger(interfaz.class.getName()).log(Level.SEVERE,
null, ex); } catch (UnsupportedLookAndFeelException ex) {
Logger.getLogger(interfaz.class.getName()).log(Level.SEVERE,
null, ex); } } if(ax.equals("Linux")){//si es un sistema linux
se aplica el skin que tiene java para linux try {
UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.Nimbu
sLookAndFeel"); interfaz w = new interfaz(); // TODO code
application logic here } catch (ClassNotFoundException ex) {
Logger.getLogger(interfaz.class.getName()).log(Level.SEVERE,
null, ex); } catch (InstantiationException ex) {
Logger.getLogger(interfaz.class.getName()).log(Level.SEVERE,
null, ex); } catch (IllegalAccessException ex) {
Logger.getLogger(interfaz.class.getName()).log(Level.SEVERE,
null, ex); } catch (UnsupportedLookAndFeelException ex) {
Logger.getLogger(interfaz.class.getName()).log(Level.SEVERE,
null, ex); } } } }
Private Sub Command1_Click()
Text3.Text = Val(Text1.Text) + Val(Text2.Text)
End Sub
Private Sub Command2_Click()
Text3.Text = Val(Text1.Text) - Val(Text2.Text)
End Sub
Private Sub Command3_Click()
Text3.Text = Val(Text1.Text) * Val(Text2.Text)
End Sub
Private Sub Command4_Click()
Text3.Text = Val(Text.Text) / Val(Text2.Text)
End Sub
Private Sub Command5_Click()
Text1.Text = ""
Text2.Text = ""
Text3.Text = ""
End Sub
Private Sub Command6_Click()
End
End Sub

3. CLASE INTERFAZ…

4. import java.awt.BorderLayout; import java.awt.Color; import
java.awt.Font; import java.awt.Insets; import java.awt.Panel;
import java.awt.event.ActionEvent; import
java.awt.event.ActionListener; import
javax.swing.BorderFactory; import javax.swing.JButton; import
javax.swing.JFrame; import javax.swing.JOptionPane; import
javax.swing.JPanel; import javax.swing.JTextField; public
class interfaz implements ActionListener{ JTextField jt1, jt2;
Panel pN, pb1, pb3; JPanel pS, pb2; JButton mc, mr, ms, mMas,
mMenos, numeros[], operaciones[]; String oper[]={"R", "C",
"+", "/", "-" ,"*", "="}, ax=""; float n1, n2, nr,
M;//variables para las operaciones int tipOp; //para controlar
el tipo de operacion que se realiza boolean t=false;//control
sobre escribir un nuevo numero despues de alguna operacion
cambia a true cuando se ha realizado una operacion public
interfaz(){ JFrame jfMain = new JFrame("Calculator");
jfMain.setLayout(new BorderLayout(4, 4)); norte(); sur();
jfMain.add(pN, BorderLayout.NORTH); jfMain.add(pS,
BorderLayout.CENTER); jfMain.setLocation(100, 80);
jfMain.setResizable(false); jfMain.setVisible(true);
jfMain.setSize(300, 380);
jfMain.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); }
public void norte(){ pN = new Panel(null); jt1 = new
JTextField(""); jt2 = new JTextField("0");
jt1.setHorizontalAlignment(JTextField.RIGHT);
jt2.setHorizontalAlignment(JTextField.RIGHT); //Quitar bordes
a los campos de texto
jt1.setBorder(BorderFactory.createLineBorder(Color.white));
jt2.setBorder(BorderFactory.createLineBorder(Color.white));
//desabilitando los campos de texto jt1.setEditable(false);
jt2.setEditable(false); jt1.setBackground(Color.white);
jt2.setBackground(Color.white); pN.add(jt1); pN.add(jt2);
jt1.setBounds(35, 10, 200, 15); jt2.setBounds(35, 25, 200,
30); pN.setSize(270, 47); pN.setVisible(true); } public void
sur(){ pS = new JPanel(new BorderLayout(6, 50));
pS.setLayout(new BorderLayout(4, 4)); botMem(); botNum();
botOpe(); pS.add(pb1, BorderLayout.NORTH); pS.add(pb2,

5. BorderLayout.CENTER); pS.add(pb3, BorderLayout.EAST);
pS.setSize(270, 330); } public void botMem(){ pb1 = new
Panel(null); mc = new JButton("MC"); mr = new JButton("MR");
ms = new JButton("MS"); mMas = new JButton("M+"); mMenos = new
JButton("M-"); mc.setFont(new Font("Arial", Font.BOLD, 11));
mr.setFont(new Font("Arial", Font.BOLD, 11)); ms.setFont(new
Font("Arial", Font.BOLD, 11)); mMas.setFont(new Font("Arial",
Font.BOLD, 11)); mMenos.setFont(new Font("Arial", Font.BOLD,
11)); mc.setMargin(new Insets(1, 1, 1, 1)); mr.setMargin(new
Insets(1, 1, 1, 1)); ms.setMargin(new Insets(1, 1, 1, 1));
mMas.setMargin(new Insets(1, 1, 1, 1)); mMenos.setMargin(new
Insets(1, 1, 1, 1)); mc.setBounds(35, 0, 33, 33);
mr.setBounds(78, 0, 33, 33); ms.setBounds(121, 0, 33, 33);
mMas.setBounds(164, 0, 33, 33); mMenos.setBounds(207, 0, 33,
33); pb1.add(mc); pb1.add(mr); pb1.add(ms); pb1.add(mMas);
pb1.add(mMenos); mc.addActionListener(this);
mr.addActionListener(this); ms.addActionListener(this);
mMas.addActionListener(this); mMenos.addActionListener(this);
pb1.setSize(270, 45); pb1.setVisible(true); } public void
botNum(){ pb2 = new JPanel(null); int nx3=121, nx2=121,
nx1=121, n3y=0, n2y=43, n1y=86; numeros = new JButton[11];
//***************************************** //bloque para
crear los botones, añadirlos y asignar numeros for (int i=0;
i<=10; i++){ if(i<=9){ numeros[i] = new JButton(""+i);
pb2.add(numeros[i]); numeros[i].setMargin(new Insets(1, 1, 1,
1)); numeros[i].addActionListener(this); } else{ numeros[i] =
new JButton("."); pb2.add(numeros[i]);
numeros[i].setMargin(new Insets(1, 1, 1, 1));
numeros[i].addActionListener(this); } }
//****************************************** //bloque para
posicionar botones for(int i=10; i>=0; i--){ if(i==10){
numeros[i].setBounds(121, 129, 35, 35); } else{ if(i<=9 &&
i>=7){ numeros[i].setBounds(nx3, n3y, 35, 35); nx3-=43; } else
if(i<=6 && i>=4){ n3y+=43; numeros[i].setBounds(nx2, n2y, 35,
35); nx2-=43; } else if(i<=3 && i>=1){ n3y+=43;
numeros[i].setBounds(nx1, n1y, 35, 35); nx1-=43; } else
if(i==0){ numeros[i].setBounds(35, 129, 78, 35); } } }

6. pb2.setSize(170, 150); pb2.setVisible(true); } public void
botOpe(){ pb3 = new Panel(null); int c=0, x=0, y=0;
operaciones = new JButton[7]; for(int i=0; i<=6; i++){
if(c<=1){ operaciones[i] = new JButton(oper[i]);
pb3.add(operaciones[i]); operaciones[i].setBounds(x, y, 30,
35); operaciones[i].setMargin(new Insets(1, 1, 1, 1));
operaciones[i].addActionListener(this); x+=33; c++; } else{
if(i==6){ x=0; y+=43; operaciones[i] = new JButton(oper[i]);
pb3.add(operaciones[i]); operaciones[i].setBounds(x, y, 65,
35); operaciones[i].setMargin(new Insets(1, 1, 1, 1));
operaciones[i].addActionListener(this); x+=33; c++; } else{
c=0; x=0; y+=43; operaciones[i] = new JButton(oper[i]);
pb3.add(operaciones[i]); operaciones[i].setBounds(x, y, 30,
35); operaciones[i].setMargin(new Insets(1, 1, 1, 1));
operaciones[i].addActionListener(this); x+=33; c++; } } }
pb3.setVisible(true); pb3.setSize(120, 200); } public boolean
isN(String ax){ try{ int n = Integer.parseInt(ax); return
true; }catch(NumberFormatException e){ return false; } }
@Override public void actionPerformed(ActionEvent e) { String
op=""; if(isN(e.getActionCommand())){ //cuando se oprimen
numeros if(jt1.getText().equals("")){ ax +=
e.getActionCommand(); jt2.setText(ax); } else{ if(tipOp==0){
if(t){ ax=""; jt1.setText(jt2.getText()); ax +=
e.getActionCommand(); jt2.setText(ax); t = false; } else{
ax=""; ax += jt2.getText()+e.getActionCommand();
jt2.setText(ax); } }else{ ax=""; ax +=
jt2.getText()+e.getActionCommand(); jt2.setText(ax); } } }
else{//cuando se oprime el resto de botones
if(e.getActionCommand().equals("R") ){ jt1.setText(""); Float
a = Float.parseFloat(jt2.getText());
jt2.setText(""+Math.sqrt(a)); }
if(e.getActionCommand().equals("C") ){ //para reiniciar
valores y limpiar pantalla tipOp=0; n1 = 0; n2 =0; nr=0;
jt1.setText(""); jt2.setText("0"); ax=""; }
if(e.getActionCommand().equals("MC")){//para limpiar la
memoria de la calculadora ms.setForeground(Color.black);
jt1.setText(""); jt2.setText("0"); M=0; }

7. if(e.getActionCommand().equals("MR")){//para mostrar valor
almacenado en la memoria jt1.setText("");
jt2.setText(String.valueOf(M));
}if(e.getActionCommand().equals("MS")){//guardar un valor en
la memoria ms.setForeground(Color.red); M =
Float.parseFloat(jt2.getText()); }
if(e.getActionCommand().equals("M+")){//sumar valor de la
pantalla con el valor de la memoria M +=
Float.parseFloat(jt2.getText()); }
if(e.getActionCommand().equals("M-")){//restar valor de la
pantalla con el valor de la memoria M -=
Float.parseFloat(jt2.getText()); }
if(e.getActionCommand().equals(".")){//usar el punto para los
decimales ax=""; if(numeros[10].isEnabled()){
numeros[10].setEnabled(false); ax = jt2.getText() +".";
jt2.setText(ax); } } if(e.getActionCommand().equals("+")
){//boton suma numeros[10].setEnabled(true); ax="";
if(tipOp==1){ }else if(tipOp==0 ){//validacion para no chocar
con otras operaciones if(jt1.getText().equals("") ){ n1 =
Float.parseFloat(jt2.getText()); ax +=
jt1.getText()+jt2.getText(); jt1.setText(ax+" + ");
jt2.setText(""); tipOp = 1; } else { if(!t){//validacion para
nueva operacion n1 = Float.parseFloat(jt2.getText()); ax +=
jt2.getText(); jt1.setText(ax+" + "); jt2.setText(""); tipOp =
1; } else{//usar otras operaciones con la suma n1 =
Float.parseFloat(jt2.getText()); ax += jt1.getText();
jt1.setText(ax+" + "); jt2.setText(""); tipOp = 1; } } } }
if(e.getActionCommand().equals("-") ){//cuando se decide
restar numeros[10].setEnabled(true); ax=""; if(tipOp==2){
}else if(tipOp==0){//validacion para no chocar con otras
operaciones if(jt1.getText().equals("")){ n1 =
Float.parseFloat(jt2.getText()); ax += jt1.getText()+
jt2.getText(); jt1.setText(ax+" - "); jt2.setText(""); tipOp =
2; } else{ if(!t){//validacion para nueva operacion n1 =
Float.parseFloat(jt2.getText()); ax += jt2.getText();
jt1.setText(ax+" - "); jt2.setText(""); tipOp = 2; }
else{//usar otras operaciones con la suma n1 =

8. Float.parseFloat(jt2.getText()); ax += jt1.getText();
jt1.setText(ax+" - "); jt2.setText(""); tipOp = 2; } } } }
if(e.getActionCommand().equals("*") ){//cuando se decide
multiplicar numeros[10].setEnabled(true); ax=""; if(tipOp==3){
}else if(tipOp==0){//validacion para no chocar con otras
operaciones if(jt1.getText().equals("")){ n1 =
Float.parseFloat(jt2.getText()); ax +=
jt1.getText()+jt2.getText(); jt1.setText(ax+" * ");
jt2.setText(""); tipOp = 3; } else{ if(!t){//validacion para
nueva operacion n1 = Float.parseFloat(jt2.getText()); ax +=
jt2.getText(); jt1.setText(ax+" * "); jt2.setText(""); tipOp =
3; } else{//usar otras operaciones con la suma n1 =
Float.parseFloat(jt2.getText()); ax += jt1.getText();
jt1.setText(ax+" * "); jt2.setText(""); tipOp = 3; } } } }
if(e.getActionCommand().equals("/") ){//cuando se decide
dividir numeros[10].setEnabled(true); ax=""; if(tipOp==4){
}else if(tipOp==0){//validacion para no chocar con otras
operaciones if(jt1.getText().equals("")){ n1 =
Float.parseFloat(jt2.getText()); ax +=
jt1.getText()+jt2.getText(); jt1.setText(ax+" / ");
jt2.setText(""); tipOp = 4; } else{ if(!t){//validacion para
nueva operacion n1 = Float.parseFloat(jt2.getText()); ax +=
jt2.getText(); jt1.setText(ax+" / "); jt2.setText(""); tipOp =
4; } else{//usar otras operaciones con la suma n1 =
Float.parseFloat(jt2.getText()); ax += jt1.getText();
jt1.setText(ax+" / "); jt2.setText(""); tipOp = 4; } } } }
if(e.getActionCommand().equals("=") &&
!jt2.getText().equals("")){ t = true; if(tipOp==1){//operacion
para la suma tipOp = 0; ax=""; ax+=jt1.getText() +
jt2.getText(); jt1.setText(ax); n2 =
Float.parseFloat(jt2.getText()); nr=n1+n2;
jt2.setText(String.valueOf(nr)); } else if(tipOp==2){
//operacion para la resta tipOp = 0; ax="";
ax+=jt1.getText()+jt2.getText(); jt1.setText(ax); n2 =
Float.parseFloat(jt2.getText()); nr=n1-n2;
jt2.setText(String.valueOf(nr)); } if(tipOp==3){ //operacion
para la multiplicacion tipOp = 0; ax="";

9. ax+=jt1.getText()+jt2.getText(); jt1.setText(ax); n2 =
Float.parseFloat(jt2.getText()); nr=n1*n2;
jt2.setText(String.valueOf(nr)); } if(tipOp==4){ //operacion
para la multiplicacion if(Float.parseFloat(jt2.getText())!=0){
tipOp = 0; ax=""; ax+=jt1.getText()+jt2.getText();
jt1.setText(ax); n2 = Float.parseFloat(jt2.getText());
nr=n1/n2; jt2.setText(String.valueOf(nr)); } else
JOptionPane.showMessageDialog(null, "No se puede realizar
divison por 0"); } } } } }