Declares the four variables to hold the two operand and compute the results. Initializing to doubles gives them a starting value and not a null value.
/** * Initializes the variables for Calculator */ double firstnum = 0.0; double secondnum = 0.0; double result = 0.0; String operation;
Initializes each Swing component in order to create text fields and buttons.
public Calculator() {
initComponents();
}
private void initComponents() {
jtxtDisplay = new javax.swing.JTextField();
jBtn1 = new javax.swing.JButton();
jBtn2 = new javax.swing.JButton();
jBtn3 = new javax.swing.JButton();
jBtn5 = new javax.swing.JButton();
jBtn4 = new javax.swing.JButton();
jBtn6 = new javax.swing.JButton();
jBtn8 = new javax.swing.JButton();
jBtn7 = new javax.swing.JButton();
jBtn9 = new javax.swing.JButton();
jBtn0 = new javax.swing.JButton();
jBtnDecimal = new javax.swing.JButton();
jBtnPlusMinus = new javax.swing.JButton();
jBtnClear = new javax.swing.JButton();
jBtnAdd = new javax.swing.JButton();
jBtnSubtract = new javax.swing.JButton();
jBtnDivide = new javax.swing.JButton();
jBtnMultiply = new javax.swing.JButton();
jBtnEqual = new javax.swing.JButton();
Configure the behavior of the window so that it closes. Additionally configure the display field's font style, size and right alignment.
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
jtxtDisplay.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
jtxtDisplay.setHorizontalAlignment(javax.swing.JTextField.RIGHT);
jBtn1.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
jBtn1.setText("1");
jBtn1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jBtn1ActionPerformed(evt);
}
});
jBtn2.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
jBtn2.setText("2");
jBtn2.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jBtn2ActionPerformed(evt);
}
});
jBtn3.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
jBtn3.setText("3");
jBtn3.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jBtn3ActionPerformed(evt);
}
});
jBtn5.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
jBtn5.setText("5");
jBtn5.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jBtn5ActionPerformed(evt);
}
});
jBtn4.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
jBtn4.setText("4");
jBtn4.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jBtn4ActionPerformed(evt);
}
});
jBtn6.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
jBtn6.setText("6");
jBtn6.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jBtn6ActionPerformed(evt);
}
});
jBtn8.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
jBtn8.setText("8");
jBtn8.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jBtn8ActionPerformed(evt);
}
});
jBtn7.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
jBtn7.setText("7");
jBtn7.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jBtn7ActionPerformed(evt);
}
});
jBtn9.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
jBtn9.setText("9");
jBtn9.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jBtn9ActionPerformed(evt);
}
});
jBtn0.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
jBtn0.setText("0");
jBtn0.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jBtn0ActionPerformed(evt);
}
});
jBtnDecimal.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
jBtnDecimal.setText(".");
jBtnDecimal.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jBtnDecimalActionPerformed(evt);
}
});
jBtnPlusMinus.setFont(new java.awt.Font("Tahoma", 1, 14)); // NOI18N
jBtnPlusMinus.setText("-/+");
jBtnPlusMinus.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jBtnPlusMinusActionPerformed(evt);
}
});
jBtnClear.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
jBtnClear.setText("C");
jBtnClear.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jBtnClearActionPerformed(evt);
}
});
jBtnAdd.setFont(new java.awt.Font("Tahoma", 0, 24)); // NOI18N
jBtnAdd.setText("+");
jBtnAdd.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jBtnAddActionPerformed(evt);
}
});
jBtnSubtract.setFont(new java.awt.Font("Tahoma", 0, 24)); // NOI18N
jBtnSubtract.setText("-");
jBtnSubtract.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jBtnSubtractActionPerformed(evt);
}
});
jBtnDivide.setFont(new java.awt.Font("Tahoma", 0, 24)); // NOI18N
jBtnDivide.setText("/");
jBtnDivide.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jBtnDivideActionPerformed(evt);
}
});
jBtnMultiply.setFont(new java.awt.Font("Tahoma", 0, 24)); // NOI18N
jBtnMultiply.setText("*");
jBtnMultiply.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jBtnMultiplyActionPerformed(evt);
}
});
jBtnEqual.setFont(new java.awt.Font("Tahoma", 1, 24)); // NOI18N
jBtnEqual.setText("=");
jBtnEqual.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jBtnEqualActionPerformed(evt);
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(47, 47, 47)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
.addComponent(jtxtDisplay, javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addGroup(layout.createSequentialGroup()
.addComponent(jBtn1, javax.swing.GroupLayout.PREFERRED_SIZE, 59, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jBtn2, javax.swing.GroupLayout.PREFERRED_SIZE, 59, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jBtn3, javax.swing.GroupLayout.PREFERRED_SIZE, 59, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(layout.createSequentialGroup()
.addComponent(jBtn4, javax.swing.GroupLayout.PREFERRED_SIZE, 59, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jBtn5, javax.swing.GroupLayout.PREFERRED_SIZE, 59, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jBtn6, javax.swing.GroupLayout.PREFERRED_SIZE, 59, javax.swing.GroupLayout.PREFERRED_SIZE))
.addGroup(layout.createSequentialGroup()
.addComponent(jBtn7, javax.swing.GroupLayout.PREFERRED_SIZE, 59, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jBtn8, javax.swing.GroupLayout.PREFERRED_SIZE, 59, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jBtn9, javax.swing.GroupLayout.PREFERRED_SIZE, 59, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGap(18, 18, 18)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jBtnAdd, javax.swing.GroupLayout.PREFERRED_SIZE, 62, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jBtnSubtract, javax.swing.GroupLayout.PREFERRED_SIZE, 62, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jBtnDivide, javax.swing.GroupLayout.PREFERRED_SIZE, 62, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jBtnMultiply, javax.swing.GroupLayout.PREFERRED_SIZE, 62, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jBtnClear, javax.swing.GroupLayout.PREFERRED_SIZE, 124, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(layout.createSequentialGroup()
.addComponent(jBtnDecimal, javax.swing.GroupLayout.PREFERRED_SIZE, 59, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jBtn0, javax.swing.GroupLayout.PREFERRED_SIZE, 59, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jBtnPlusMinus, javax.swing.GroupLayout.PREFERRED_SIZE, 59, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jBtnEqual, javax.swing.GroupLayout.PREFERRED_SIZE, 139, javax.swing.GroupLayout.PREFERRED_SIZE))))
.addContainerGap(53, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGap(55, 55, 55)
.addComponent(jtxtDisplay, javax.swing.GroupLayout.PREFERRED_SIZE, 67, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jBtn1, javax.swing.GroupLayout.PREFERRED_SIZE, 54, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jBtn2, javax.swing.GroupLayout.PREFERRED_SIZE, 54, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jBtn3, javax.swing.GroupLayout.PREFERRED_SIZE, 54, javax.swing.GroupLayout.PREFERRED_SIZE))
.addComponent(jBtnAdd, javax.swing.GroupLayout.PREFERRED_SIZE, 54, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jBtn4, javax.swing.GroupLayout.PREFERRED_SIZE, 54, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jBtn5, javax.swing.GroupLayout.PREFERRED_SIZE, 54, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jBtn6, javax.swing.GroupLayout.PREFERRED_SIZE, 54, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jBtnSubtract, javax.swing.GroupLayout.PREFERRED_SIZE, 54, javax.swing.GroupLayout.PREFERRED_SIZE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jBtn7, javax.swing.GroupLayout.PREFERRED_SIZE, 54, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jBtn8, javax.swing.GroupLayout.PREFERRED_SIZE, 54, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jBtn9, javax.swing.GroupLayout.PREFERRED_SIZE, 54, javax.swing.GroupLayout.PREFERRED_SIZE))
.addComponent(jBtnDivide, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jBtnMultiply, javax.swing.GroupLayout.PREFERRED_SIZE, 54, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jBtnPlusMinus, javax.swing.GroupLayout.PREFERRED_SIZE, 54, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jBtn0, javax.swing.GroupLayout.PREFERRED_SIZE, 54, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jBtnDecimal, javax.swing.GroupLayout.PREFERRED_SIZE, 54, javax.swing.GroupLayout.PREFERRED_SIZE)))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jBtnClear, javax.swing.GroupLayout.PREFERRED_SIZE, 55, javax.swing.GroupLayout.PREFERRED_SIZE)
.addComponent(jBtnEqual, javax.swing.GroupLayout.PREFERRED_SIZE, 55, javax.swing.GroupLayout.PREFERRED_SIZE))
.addContainerGap(24, Short.MAX_VALUE))
);
pack();
}//
Configure the behavior of the window so that it closes. Additionally configure the display field's font style, size and right alignment.
private void jBtnClearActionPerformed(java.awt.event.ActionEvent evt) {
jtxtDisplay.setText("");
}
private void jBtn1ActionPerformed(java.awt.event.ActionEvent evt) {
String enterNum = jtxtDisplay.getText() + jBtn1.getText();
jtxtDisplay.setText(enterNum);
}
private void jBtn2ActionPerformed(java.awt.event.ActionEvent evt) {
String enterNum = jtxtDisplay.getText() + jBtn2.getText();
jtxtDisplay.setText(enterNum);
}
private void jBtn3ActionPerformed(java.awt.event.ActionEvent evt) {
String enterNum = jtxtDisplay.getText() + jBtn3.getText();
jtxtDisplay.setText(enterNum);
}
private void jBtn4ActionPerformed(java.awt.event.ActionEvent evt) {
String enterNum = jtxtDisplay.getText() + jBtn4.getText();
jtxtDisplay.setText(enterNum);
}
private void jBtn5ActionPerformed(java.awt.event.ActionEvent evt) {
String enterNum = jtxtDisplay.getText() + jBtn5.getText();
jtxtDisplay.setText(enterNum);
}
private void jBtn6ActionPerformed(java.awt.event.ActionEvent evt) {
String enterNum = jtxtDisplay.getText() + jBtn6.getText();
jtxtDisplay.setText(enterNum);
}
private void jBtn7ActionPerformed(java.awt.event.ActionEvent evt) {
String enterNum = jtxtDisplay.getText() + jBtn7.getText();
jtxtDisplay.setText(enterNum);
}
private void jBtn8ActionPerformed(java.awt.event.ActionEvent evt) {
String enterNum = jtxtDisplay.getText() + jBtn8.getText();
jtxtDisplay.setText(enterNum);
}
private void jBtn9ActionPerformed(java.awt.event.ActionEvent evt) {
String enterNum = jtxtDisplay.getText() + jBtn9.getText();
jtxtDisplay.setText(enterNum);
}
private void jBtn0ActionPerformed(java.awt.event.ActionEvent evt) {
String enterNum = jtxtDisplay.getText() + jBtn0.getText();
jtxtDisplay.setText(enterNum);
}
private void jBtnAddActionPerformed(java.awt.event.ActionEvent evt) {
firstnum = Double.parseDouble(jtxtDisplay.getText());
jtxtDisplay.setText("");
operation = "+";
}
The mathematical operations are preformed here in order to return the correct results. Additionally there are handlers for plus, minus and clear.
private void jBtnEqualActionPerformed(java.awt.event.ActionEvent evt) {
secondnum = Double.parseDouble(jtxtDisplay.getText());
String answer;
switch(operation)
{
// Cases for mathematical operations
case "+":
result = firstnum + secondnum;
break;
case "-":
result = firstnum - secondnum;
break;
case "/":
result = firstnum / secondnum;
break;
case "*":
result = firstnum * secondnum;
break;
}
// Displats result in format
answer = String.format("%.3f", result);
jtxtDisplay.setText(answer);
}
private void jBtnSubtractActionPerformed(java.awt.event.ActionEvent evt) {
firstnum = Double.parseDouble(jtxtDisplay.getText());
jtxtDisplay.setText("");
operation = "-";
}
private void jBtnDivideActionPerformed(java.awt.event.ActionEvent evt) {
firstnum = Double.parseDouble(jtxtDisplay.getText());
jtxtDisplay.setText("");
operation = "/";
}
private void jBtnMultiplyActionPerformed(java.awt.event.ActionEvent evt) {
firstnum = Double.parseDouble(jtxtDisplay.getText());
jtxtDisplay.setText("");
operation = "*";
}
private void jBtnPlusMinusActionPerformed(java.awt.event.ActionEvent evt) {
if(!jtxtDisplay.getText().equals(""))
{
double value = Double.parseDouble(jtxtDisplay.getText());
value *= -1;
jtxtDisplay.setText(String.format("%.3f",value));
}
}
private void jBtnDecimalActionPerformed(java.awt.event.ActionEvent evt) {
if(jtxtDisplay.getText().indexOf(".") < 0)
{
String enterNum = jtxtDisplay.getText() + jBtnDecimal.getText();
jtxtDisplay.setText(enterNum);
}
}
This sections sets up the app launch and hold the variable declarations.
/**
* @param args the command line arguments
*/
public static void main(String args[]) {
/* Set the Nimbus look and feel */
//
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(Calculator.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(Calculator.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(Calculator.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(Calculator.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new Calculator().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JButton jBtn0;
private javax.swing.JButton jBtn1;
private javax.swing.JButton jBtn2;
private javax.swing.JButton jBtn3;
private javax.swing.JButton jBtn4;
private javax.swing.JButton jBtn5;
private javax.swing.JButton jBtn6;
private javax.swing.JButton jBtn7;
private javax.swing.JButton jBtn8;
private javax.swing.JButton jBtn9;
private javax.swing.JButton jBtnAdd;
private javax.swing.JButton jBtnClear;
private javax.swing.JButton jBtnDecimal;
private javax.swing.JButton jBtnDivide;
private javax.swing.JButton jBtnEqual;
private javax.swing.JButton jBtnMultiply;
private javax.swing.JButton jBtnPlusMinus;
private javax.swing.JButton jBtnSubtract;
private javax.swing.JTextField jtxtDisplay;
// End of variables declaration