This code is for creating a simple calculator using Java Swing.
Creating GUI Components: The code creates a JFrame (window) with a JTextField (for displaying input and result) and several JButtons (for numbers, arithmetic operators, and clear functionality).
Layout and Size: It sets the bounds (position and size) for each component within the JFrame.
Action Listeners: Action listeners are added to each button to handle user interactions. When a button is clicked, its corresponding action is triggered.
For numeric buttons (0-9), a single action listener is shared among all of them. When a numeric button is clicked, the current text in the JTextField is retrieved, and the clicked number is appended to it.
For operator buttons (+, -, *, /), another action listener is shared among them. When an operator button is clicked, it appends the operator to the current text in the JTextField, separating it with spaces.
The "Clear" button (C) has a separate action listener to clear the text field when clicked.
The "=" button performs the calculation based on the expression entered in the text field. It parses the expression, evaluates it, and displays the result in the text field.
Performing Calculations: The calculation is performed when the "=" button is clicked. It extracts the expression from the text field, splits it into parts (operands and operator), performs the arithmetic operation, and displays the result.
Displaying the GUI: Finally, all the components are added to the JFrame, the layout is set to null (custom positioning), and the JFrame is set to be visible.
import java.awt.event.*;
import javax.swing.*;
public class Main {
public static void main(String[] args) {
JFrame f = new JFrame("Calculator");
JTextField t1 = new JTextField();
JButton b1 = new JButton("1");
JButton b2 = new JButton("2");
JButton b3 = new JButton("3");
JButton b4 = new JButton("4");
JButton b5 = new JButton("5");
JButton b6 = new JButton("6");
JButton b7 = new JButton("7");
JButton b8 = new JButton("8");
JButton b9 = new JButton("9");
JButton b0 = new JButton("0");
JButton bclear = new JButton("C");
JButton bsum = new JButton("+");
JButton bmin = new JButton("-");
JButton bmul = new JButton("*");
JButton bdiv = new JButton("/");
JButton beq = new JButton("=");
t1.setBounds(5, 20, 300, 20);
b1.setBounds(10, 60, 50, 30);
b2.setBounds(70, 60, 50, 30);
b3.setBounds(130, 60, 50, 30);
b4.setBounds(10, 100, 50, 30);
b5.setBounds(70, 100, 50, 30);
b6.setBounds(130, 100, 50, 30);
b7.setBounds(10, 140, 50, 30);
b8.setBounds(70, 140, 50, 30);
b9.setBounds(130, 140, 50, 30);
b0.setBounds(10, 180, 50, 30);
bclear.setBounds(70, 180, 50, 30);
bsum.setBounds(190, 60, 50, 30);
bmin.setBounds(190, 100, 50, 30);
bmul.setBounds(190, 140, 50, 30);
bdiv.setBounds(190, 180, 50, 30);
beq.setBounds(130, 180, 50, 30);
ActionListener numericListener = new ActionListener() {
public void actionPerformed(ActionEvent e) {
String currentText = t1.getText();
JButton button = (JButton) e.getSource();
t1.setText(currentText + button.getText());
}
};
b1.addActionListener(numericListener);
b2.addActionListener(numericListener);
b3.addActionListener(numericListener);
b4.addActionListener(numericListener);
b5.addActionListener(numericListener);
b6.addActionListener(numericListener);
b7.addActionListener(numericListener);
b8.addActionListener(numericListener);
b9.addActionListener(numericListener);
b0.addActionListener(numericListener);
bclear.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
t1.setText("");
}
});
ActionListener operatorListener = new ActionListener() {
public void actionPerformed(ActionEvent e) {
String currentText = t1.getText();
JButton button = (JButton) e.getSource();
t1.setText(currentText + " " + button.getText() + " ");
}
};
bsum.addActionListener(operatorListener);
bmin.addActionListener(operatorListener);
bmul.addActionListener(operatorListener);
bdiv.addActionListener(operatorListener);
beq.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String expression = t1.getText();
String[] parts = expression.split(" ");
double result = Double.parseDouble(parts[0]);
char operator = parts[1].charAt(0);
double operand = Double.parseDouble(parts[2]);
switch (operator) {
case '+':
result += operand;
break;
case '-':
result -= operand;
break;
case '*':
result *= operand;
break;
case '/':
if (operand != 0)
result /= operand;
else
t1.setText("Error: Division by zero");
break;
default:
t1.setText("Error: Invalid operator");
return;
}
t1.setText(Double.toString(result));
}
});
f.add(b1);
f.add(b2);
f.add(b3);
f.add(b4);
f.add(b5);
f.add(b6);
f.add(b7);
f.add(b8);
f.add(b9);
f.add(b0);
f.add(bclear);
f.add(bsum);
f.add(bmin);
f.add(bmul);
f.add(bdiv);
f.add(beq);
f.add(t1);
f.setSize(400, 400);
f.setLayout(null);
f.setVisible(true);
}
}
