Thread: Math program problem.

Hi, so I have already posted once, about another program. That didn't work so well, so I went back a step.

So I want a program, that will read a list of simple math problems from a text file. They would like in the file
4 + 3
2 * 3
12 / 4

ect.

So, I want the program to read the file, go line by line. Then split each line into, the 2 integers, and the operator. Than I use the if else stuff, to do the calculations.

So, I have something that should do that. But when I run it, all the answers are zero. Can someone have a look, see if I have made a mistake, or if I am doing it wrong. THanks

import java.io.*;
class Calculator {
	 public static void main(String args[]){
		 int z = 0; 
		 try{
			  // Open the file that is the first 
			  // command line parameter
 
			  FileInputStream fstream = new FileInputStream("C:/Users/Dylanka/Desktop/Test1.txt");
 
			  // Get the object of DataInputStream
 
			  DataInputStream in = new DataInputStream(fstream);
			  BufferedReader br = new BufferedReader(new InputStreamReader(in));
			  String strLine;
 
			  //Read File Line By Line
 
			  while ((strLine = br.readLine()) != null)   {
 
				  String[] Parts = strLine.split(" ");	
 
				  String op = Parts[1];			
				  int x = Integer.parseInt(Parts[0]);		
				  int y = Integer.parseInt(Parts[2]);		
				  {
 
 
					  if(op == "+"){			
							z =x + y;	
					  }
 
					  else if(op == "-"){	
							z = x - y;	
					  }
 
					  else if(op == "/"){	
							z = x / y;
					  }
 
					  else if (op == "*"){	
							z = x * y;	
					  }
					  System.out.println(x + " " + op + " " + y + " = " + z);
				  }
 
			  }
			  //Close the input stream
 
			  in.close();
 
 
		    }catch (Exception e){//Catch exception if any
 
		  System.err.println("Error: " + e.getMessage());
		  }
	  }
}

I tested your program and got it to work. You have to look at your op variable. You need to store a char there instead of a single character string. Look at the charAt(0) method. When you evaluate in your if statements use chars ' ' in stead of string literals " ".

Hope it helps