Simple Calculator in Java
Here's the screenshot below:
It can only perform one operation at a time.
If you have any question about the code, just comment below. :)
import java.lang.*;
import java.awt.*;
import java.awt.event.*;
public class calculator extends
Frame implements ActionListener {
Button btn1 = new Button("1");
Button btn2 = new Button("2");
Button btn3 = new Button("3");
Button plus = new Button("+");
Button btn4 = new Button("4");
Button btn5 = new Button("5");
Button btn6 = new Button("6");
Button minus = new Button("-");
Button btn7 = new Button("7");
Button btn8 = new Button("8");
Button btn9 = new Button("9");
Button times = new Button("*");
Button btn_clr = new Button("C");
Button btn0 = new Button("0");
Button divide = new Button("/");
Button ekwals = new Button("=");
TextField txt = new TextField(20);
String str_number = "";
int operation = 0;
double number1 = 0;
double number2 = 0;
double result = 0;
String[] str = null;
public calculator() {
Panel base = new Panel();
Panel NumberPanel = new Panel();
base.setLayout(new BorderLayout());
NumberPanel.setLayout(new GridLayout(4,4));
NumberPanel.add(btn1);
btn1.addActionListener(this);
NumberPanel.add(btn2);
btn2.addActionListener(this);
NumberPanel.add(btn3);
btn3.addActionListener(this);
NumberPanel.add(plus);
plus.addActionListener(this);
NumberPanel.add(btn4);
btn4.addActionListener(this);
NumberPanel.add(btn5);
btn5.addActionListener(this);
NumberPanel.add(btn6);
btn6.addActionListener(this);
NumberPanel.add(minus);
minus.addActionListener(this);
NumberPanel.add(btn7);
btn7.addActionListener(this);
NumberPanel.add(btn8);
btn8.addActionListener(this);
NumberPanel.add(btn9);
btn9.addActionListener(this);
NumberPanel.add(times);
times.addActionListener(this);
NumberPanel.add(btn0);
btn0.addActionListener(this);
NumberPanel.add(btn_clr);
btn_clr.addActionListener(this);
NumberPanel.add(ekwals);
ekwals.addActionListener(this);
NumberPanel.add(divide);
divide.addActionListener(this);
txt.setEditable(false);
txt.setBackground(Color.black);
txt.setForeground(Color.green);
base.add(NumberPanel,BorderLayout.CENTER);
base.add(txt,BorderLayout.NORTH);
add(base,BorderLayout.CENTER);
}
public void actionPerformed(ActionEvent e) {
if(e.getSource()==btn1) {
txt.setText("1");
str_number+=txt.getText();
txt.setText(str_number); }
else if(e.getSource()==btn2) {
txt.setText("2");
str_number+=txt.getText();
txt.setText(str_number); }
else if(e.getSource()==btn3) {
txt.setText("3");
str_number+=txt.getText();
txt.setText(str_number); }
else if(e.getSource()==btn4) {
txt.setText("4");
str_number+=txt.getText();
txt.setText(str_number); }
else if(e.getSource()==btn5) {
txt.setText("5");
str_number+=txt.getText();
txt.setText(str_number); }
else if(e.getSource()==btn6) {
txt.setText("6");
str_number+=txt.getText();
txt.setText(str_number); }
else if(e.getSource()==btn7) {
txt.setText("7");
str_number+=txt.getText();
txt.setText(str_number); }
else if(e.getSource()==btn8) {
txt.setText("8");
str_number+=txt.getText();
txt.setText(str_number); }
else if(e.getSource()==btn9) {
txt.setText("9");
str_number+=txt.getText();
txt.setText(str_number); }
else if(e.getSource()==btn0) {
txt.setText("0");
str_number+=txt.getText();
txt.setText(str_number); }
else if(e.getSource()==plus) {
if(operation==0 & str_number!="") {
number1=Integer.parseInt(str_number);
txt.setText("+");
str_number+=txt.getText();
txt.setText(str_number);
operation=1;
}
else {txt.setText(str_number);}
}
else if(e.getSource()==minus) {
if(operation==0 & str_number!="") {
number1=Integer.parseInt(str_number);
txt.setText("-");
str_number+=txt.getText();
txt.setText(str_number);
operation=2;
}
else { txt.setText(str_number); }
}
else if(e.getSource()==times) {
if(operation==0 & str_number!="") {
number1=Integer.parseInt(str_number);
txt.setText("*");
str_number+=txt.getText();
txt.setText(str_number);
operation=3;
}
else { txt.setText(str_number); }
}
else if(e.getSource()==divide) {
if(operation==0 & str_number!="") {
number1=Integer.parseInt(str_number);
txt.setText("/");
str_number+=txt.getText();
txt.setText(str_number);
operation=4;
}
else { txt.setText(str_number); }
}
else if(e.getSource()==ekwals) {
if(operation!=0 & str_number!="") {
txt.setText("=");
str_number+=txt.getText();
txt.setText(str_number);
switch(operation) {
case 1: {
str = str_number.split("\\+");
number2=Integer.parseInt(str[1].replace("=",""));
result=number1+number2;
txt.setText(Double.toString(result));
break;
}
case 2: {
str = str_number.split("\\-");
number2=Integer.parseInt(str[1].replace("=",""));
result=number1-number2;
txt.setText(Double.toString(result));
break;
}
case 3: {
str = str_number.split("\\*");
number2=Integer.parseInt(str[1].replace("=",""));
result=number1*number2;
txt.setText(Double.toString(result));
break;
}
case 4: {
str = str_number.split("\\/");
number2=Integer.parseInt(str[1].replace("=",""));
result=number1/number2;
txt.setText(Double.toString(result));
break;
}
}
btn0.setEnabled(false);
btn1.setEnabled(false);
btn2.setEnabled(false);
btn3.setEnabled(false);
btn4.setEnabled(false);
btn5.setEnabled(false);
btn6.setEnabled(false);
btn7.setEnabled(false);
btn8.setEnabled(false);
btn9.setEnabled(false);
plus.setEnabled(false);
minus.setEnabled(false);
times.setEnabled(false);
divide.setEnabled(false);
ekwals.setEnabled(false);
}
else { txt.setText(""); }
}
else if(e.getSource()==btn_clr) {
txt.setText("");
str_number = "";
operation = 0;
number1 = 0;
number2 = 0;
result = 0;
btn0.setEnabled(true);
btn1.setEnabled(true);
btn2.setEnabled(true);
btn3.setEnabled(true);
btn4.setEnabled(true);
btn5.setEnabled(true);
btn6.setEnabled(true);
btn7.setEnabled(true);
btn8.setEnabled(true);
btn9.setEnabled(true);
plus.setEnabled(true);
minus.setEnabled(true);
times.setEnabled(true);
divide.setEnabled(true);
ekwals.setEnabled(true);
}
}
public static void main(String[] args) {
calculator calc = new calculator();
calc.setVisible(true);
calc.setSize(200,200);
calc.setResizable(false);
calc.setTitle("Calculator");
}
}
If you have any question about the code, just comment below. :)
