BufferedReader is there method while next exist?

[Anissa Pary]

Hello, Java genius!
Can anyone help please is there a method on a buffereReader while the next on the file exist do when there is no new lines finish. I searched for that but could not find smth. similar do you know how to do that. This is my code I wanted to do like while there is a new line in the file put it in an arrayList when there is no more lines stop.

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;
import java.util.ArrayList;

public class MathApplication {
	public static String equation;
	public static String line;
	public static ArrayList equations;

	public MathApplication(String equation) {
		this.equation = equation;
	}

	public static void main(String[] args) throws IOException {
		FileReader fr = new FileReader("D:\\Equation.txt");
		BufferedReader br = new BufferedReader(fr);

		// for(int i =0; i<)
		// MathApplication e1 = new MathApplication();
	}
}

Equation.txt

2+2
4/3
15*2
14$5

Ok, I added

while ((strLine = br.readLine()) != null) {
			equations.add(strLine);
		}
		System.out.println(equations);

but now it shows NullPointerException when I debugged it it does two tmes

 equations.add(strLine);

and then throws Exception I think it is because there is no an increasement like int i =0; i++

[Wendy L Gibbons]

there isn't one in the api, and the 1st five examples i found showed how to do it.

adding example into your search is very helpfull.

[Matthew Brown]

Just check the return value of the readLine() method. It will return null when it reaches the end of the file.

[Jeff Verdegan]

Anissa Pary wrote:

Ok, I added [code=java]
while ((strLine = br.readLine()) != null) {
			equations.add(strLine);
		}
		System.out.println(equations);

but now it shows NullPointerException

The only way that code can throw NPE is if br is null or equations is null. And that can only happen if you didn't initialize them, or if you explicitly set them to null. It will not happen from reaching the end of the file. So either you are making one of those things be null, or the NPE is coming from somewhere else.

[Wendy L Gibbons]

if you aren't working in an IDE so can't debug, System.out.println() is your friend print out the variables the line before you use them.