Java

import java.util.*;
import java.text.*;
import javax.swing.*;
class Lab4Part2{
public static void main (String[] args) {
String ex1;
double sum, F, a=0, b=0;
JFrame myWindow=new JFrame();
myWindow.setSize(500,400);
myWindow.setTitle("Calculator");
myWindow.setVisible(true);
myWindow.setLocation(600,200);
ex1=JOptionPane.showInputDialog(myWindow, "Enter an expression");
//F=Double.parseDouble(ex1);  You cannot parse the whole string as double since it has 
              //a '+' sign and besides the user might enter other invalid Characters
//Validate that the user entry is in the valid form so check the input to see if there 
      //is anything else besides numbers and + sign in the input, something like this
//"^\\d+[\\+]\\d+$" is a regex to validate the i/p, try researching on your own to figure 
              //out
if(Pattern.compile("^\\d+[\\+]\\d+$").matcher(ex1).find()) {
  String[] inputnums = ex1.split("+");
  a = Double.parseDouble(inputnums[0]);
  b = Double.parseDouble(inputnums[1]);
}
else
 //throw an exception informing the user that the i/p is incorrect.

//sum=(a+B); mind the case
//sum=a+b;
JOptionPane.showMessageDialog(myWindow, "The sum is "+sum);
}
}

vivek886 wrote:

Simple

vivek886 wrote:

Simple

vivek886 wrote:

Can you please tell me the solution.

vivek886 wrote:

is this program right to check whether string is alpha or numeric