You are to write a program name calculator.java that evaluates an infix expressi

Question

You are to write a program name calculator.java that evaluates an infix expression entered by the user. The expression may contain the following tokens:
(1)   Integer constants (a series of decimal digits).
(2)   x (representing a value to be supplied later).
(3)   Unary operators (+ and -).
(4)   Binary operators (+, -, *, / and %).
(5)   Parentheses

Spaces between tokens are allowed but not required. The program will convert the expression to postfix (RPN) form and display the converted expression. In the postfix version of the expression, unary + will be removed, and the unary

Explanation / Answer

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
class Calculator implements ActionListener
{
int c,n;
String s1,s2,s3,s4,s5;
Frame f;
JButton b1,b2,b3,b4,b5,b6,b7,b8,b9,b10,b11,b12,b13,b14,b15,b16;
Panel p;
TextField tf1;
GridLayout gl;
Calculator()
{
f=new Frame("Calculator");
p=new Panel();
b1=new JButton("0");
b1.addActionListener(this);
b2=new JButton("1");
b2.addActionListener(this);
b3=new JButton("2");
b3.addActionListener(this);
b4=new JButton("3");
b4.addActionListener(this);
b5=new JButton("4");
b5.addActionListener(this);
b6=new JButton("5");
b6.addActionListener(this);
b7=new JButton("6");
b7.addActionListener(this);
b8=new JButton("7");
b8.addActionListener(this);
b9=new JButton("8");
b9.addActionListener(this);
b10=new JButton("9");
b10.addActionListener(this);
b11=new JButton("+");
b11.addActionListener(this);
b12=new JButton("-");
b12.addActionListener(this);
b13=new JButton("x");
b13.addActionListener(this);
b14=new JButton("/");
b14.addActionListener(this);
b15=new JButton("=");
b15.addActionListener(this);
b16=new JButton("A/C");
b16.addActionListener(this);
tf1=new TextField(20);
p.add(tf1);
tf1.setBackground(Color.yellow);
gl=new GridLayout(4,4,10,20);
p.setLayout(gl);
p.add(b1);p.add(b2);p.add(b3);p.add(b4);p.add(b5);p.add(b6);p.add(b7);p.add(b8);p.add(b9);p.add(b10);p.add(b11);p.add(b12);p.add(b13);p.add(b14);p.add(b15);p.add(b16);
f.add(p);
f.setSize(100,200);
f.setVisible(true);
}
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==b1)
{
s3=tf1.getText();
s4="0";
s5=s3+s4;
tf1.setText(s5);
}
if(e.getSource()==b2)
{
s3=tf1.getText();
s4="1";
s5=s3+s4;
tf1.setText(s5);
}
if(e.getSource()==b3)
{
s3=tf1.getText();
s4="2";
s5=s3+s4;
tf1.setText(s5);
}
if(e.getSource()==b4)
{
s3=tf1.getText();
s4="3";
s5=s3+s4;
tf1.setText(s5);
}
if(e.getSource()==b5)
{
s3=tf1.getText();
s4="4";
s5=s3+s4;
tf1.setText(s5);
}
if(e.getSource()==b6)
{
s3=tf1.getText();
s4="5";
s5=s3+s4;
tf1.setText(s5);
}
if(e.getSource()==b7)
{
s3=tf1.getText();
s4="6";
s5=s3+s4;
tf1.setText(s5);
}
if(e.getSource()==b8)
{
s3=tf1.getText();
s4="7";
s5=s3+s4;
tf1.setText(s5);
}
if(e.getSource()==b9)
{
s3=tf1.getText();
s4="8";
s5=s3+s4;
tf1.setText(s5);
}
if(e.getSource()==b10)
{
s3=tf1.getText();
s4="9";
s5=s3+s4;
tf1.setText(s5);
}
if(e.getSource()==b11)
{
s1=tf1.getText();
tf1.setText("");
c=1;
}
if(e.getSource()==b12)
{
s1=tf1.getText();
tf1.setText("");
c=2;
}
if(e.getSource()==b13)
{
s1=tf1.getText();
tf1.setText("");
c=3;
}
if(e.getSource()==b14)
{
s1=tf1.getText();
tf1.setText("");
c=4;
}
if(e.getSource()==b15)
{
s2=tf1.getText();
if(c==1)
{
n=Integer.parseInt(s1)+Integer.parseInt(s2);
tf1.setText(String.valueOf(n));
}
else
if(c==2)
{
n=Integer.parseInt(s1)-Integer.parseInt(s2);
tf1.setText(String.valueOf(n));
}
else
if(c==3)
{
n=Integer.parseInt(s1)*Integer.parseInt(s2);
tf1.setText(String.valueOf(n));
}
else
if(c==4)
{
n=Integer.parseInt(s1)/Integer.parseInt(s2);
tf1.setText(String.valueOf(n));
}
}
if(e.getSource()==b16)
{
tf1.setText("");
}
}
public static void main(String args[])
{
Calculator c=new Calculator();
}
}

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