Java Reader, read method for text file

Question

I have a text file called test.txt with the word hello. I am trying to read it using Reader.read() method and print the contents to console. However when I run it I am just getting the number 104 printed on console and nothing else (I get the same number printed even if I change the text to more/less characters). Any ideas why it is behaving this way and how can I modify this existing code to print the contents of test.txt as a string on console? Here is my code:

public static void spellCheck(Reader r) throws IOException{
    Reader newReader = r;
    System.out.println(newReader.read());
}

and my main method I am using to test the above:

public static void main (String[] args)throws IOException{
    Reader test = new BufferedReader(new FileReader("test.txt"));
    spellCheck(test);
}

@peter.murray.rust: no, it's returning a char as an int, or -1, as every Reader. — JB Nizet
– JB Nizet, Commented May 19, 2013 at 21:20
You're reading one character and you're printing one character. The code is working as designed. What's the question? — user207421
– user207421, Commented May 19, 2013 at 23:25

SLaks · Accepted Answer · 2013-05-19 21:18:42Z

4

read() is doing exactly what it's supposed to:

Reads a single character. This method will block until a character is available, an I/O error occurs, or the end of the stream is reached.

(emphasis added)

Instead, you can call BufferedReader.readLine() in a loop.

answered May 19, 2013 at 21:18

SLaks

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1 Comment

user1894469 Over a year ago

Thanks for the link, the answer was staring right at me. Unfortunately I could only select one as the answer, but your help and prompt reply is appreciated.

JB Nizet · Accepted Answer · 2013-05-19 21:18:47Z

2

As the javadoc indicates, the read() method reads a single char, and returns it as an int (in order to be able to return -1 to indicate the end of the stream). To print the int as a char, just cast it:

int c = reader.read();
if (c != -1) {
    System.out.println((char) c);
}
else {
    System.out.println("end of the stream");
}

To read everything, loop until you get -1, or read line by line until you get null.

answered May 19, 2013 at 21:18

JB Nizet

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2 Comments

user1894469 Over a year ago

How do I read line by line? My method is taking (Reader r) as a parameter, and I do not want to change that. Then I cannot say BufferedReader newReader = r as that gives me incompatible type. But as far as I can tell from the docs, Reader does not have a readLine() method.

JB Nizet Over a year ago

BufferedReader is the class allowing to read line by line. So if that's what you want to do, wrap the Reader into a BufferedReader in your method. But you don't need to read line by line to read everything. You can simply use this read method (for better performance) until it returns -1.

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