Rpn Calculator Java

[xafizzle]

I'm making an RPN calculator that reads input from a file using the FileReader Scanner. It works using a .txt file that has numbers and operations entered on separate likes like such:

 

5

6

8

+

4

-

sqrt

 

So in that case it would add 8 to 6, subtract 4 from the sum of that, and take the square root of that answer. All of that works fine until the end of the file when there is no more information to parse. I get a NoSuchNumberException and java doesn't let you catch that exception for whatever reason. I got around that by using a try/finally but I want to know if there's any other way to do it that's more efficient. Also, an explanation as to why you can't catch that exception would be appreciated.

[Short]

You could use a loop to check if it's at end of file, but I don't know java.

 

while (get input) {
do some stuff
}

Edited March 1, 2014 by Short

[xafizzle]

No cause then it runs into that same problem. As far as I know a try block is the only way to get around it but I just don't understand why you can't catch that exception

[Guest The_Monkey]

or you could make a nice gui...

[xafizzle]

The assignment was to read from a file, not from individual user input.

[Papa John]

http://stackoverflow.com/questions/13927326/reading-input-till-eof-in-java

[xafizzle]

It doesn't work that simply for me. Perhaps there's something I'm forgetting as I'm not coding it the same way but it doesn't work unless I include the hasMore method.

 

The code:

import java.util.Scanner;
import java.util.ArrayList;
import java.lang.Math;
import java.io.*;
public class StackedCalculator {
public static void main(String[] args)throws IOException{
 StackedCalculator calc = new StackedCalculator();
 calc.operations();
 Scanner scanner = new Scanner(new FileReader("myFile.txt"));
 String inputS = scanner.nextLine();
 ArrayList<Double> stack = new ArrayList<Double>();
	 while (inputS != null) {
		 if (calc.isNumeric(inputS)) {
			 calc.push(Double.parseDouble(inputS), stack);
			 System.out.println(calc.peek(stack));
			 /*if(!hasMore(scanner)) {
				 break;
			 }*/
			 inputS = scanner.nextLine();
		 }
		 else if (calc.isValid(inputS) && stack.size() > 0) {
			 calc.push(calc.calculate(inputS, stack), stack);
			 System.out.println(calc.peek(stack));
			 /*if(!hasMore(scanner)) {
				 break;
			 }*/
			 inputS = scanner.nextLine();
		 }
		 else if (!calc.isValid(inputS)) {
			 System.out.print("Not a valid operation");
			 inputS = scanner.nextLine();
		 }
	 }
}
public static boolean hasMore (Scanner scanner) {
 if (scanner.hasNext()) return true;
 else {
	 System.out.print("No more elements!");
	 return false;
 }
}
}

 

 

 

And before I get shit for using stack methods improperly or inefficiently, the assignment was also to write my own stack methods using arrays.

Edited March 3, 2014 by xafizzle

[captaincracker]

If you send me your code I can finish it and send it back, I always like practice

[Guest The_Monkey]

If you send me your code I can finish it and send it back, I always like practice

 

If it is for school, please don't do this.

[captaincracker]

If it is for school, please don't do this.

 

 

I just figured he was making it for himself

[xafizzle]

I'm not asking for it to be done for me. I actually finished it. I'll give a pastebin link when I get back. I just felt like it was really inefficient. And I don't understand why I can't catch that exception.