Thread: Little String Problem

Hey, I've just started messing around with reading from text documents and I've done fairly well in my experiments so-far; I just ran into a small problem with the one part of the code that I was sure would work. When running the program everything runs perfectly except for my if statements. Every single character, which is either a 1 or a 0, is always printing ""+charText+" is null." when I run the program. I haven't done much with strings/char variables before so I'm probably making some simple mistake, if anyone can enlighten me please do so.

MapReaderTest.java

import java.io.*;
 
class MapReaderTest
{
	public static void main (String args[]) throws IOException
	{
		String lineText;
		char charText;
		int lineCounter =0;
		int characterCounter = 0;
 
		BufferedReader inputStream = new BufferedReader(new FileReader("Map.txt"));
 
		while( (lineText = inputStream.readLine()) != null) //While the current line doesn't have nothingon it then keep looping
		{
			lineCounter++;
			System.out.println(""+lineText+" is the current line.");
 
			for(int i = 0; i < lineText.length(); i++) //Loops through each character in the string until the string ends.
			{
				charText = lineText.charAt(i);
 
				if(charText == 0)
				{
					System.out.println(""+charText+" is a zero.");
				}
				else if(charText == 1)
				{
					System.out.println(""+charText+" is a one.");
				}
				else
				{
					System.out.println(""+charText+" is null.");
				}
			}
		}
		inputStream.close();
	}
}

Map.txt

0110101101
1001010010
0001110001
1110001100

charText is a variable of type char, so it won't ever be null - rather it should have some numeric value.

The output from

System.out.println(""+charText+" is null.");

should have told you what that value is for the two characters. If the char values of the zero and one characters are not clear to you from the program's output, post that output.

The two char values you test for (0 an 1) are very likely not the values associated with the zero an one characters. Rather than try and commit to memory all the values we use character literal notation:

if(charText == '0') // '0' is a character literal
{
    // this code will be executed when charText is the zero character.
}