Java Community | Help. Code. Learn.•8mo ago

Reading lines in a file, but not terminating

Hello, I did a code to iterate through a text file. I am doing it with Iterator<String>. The problem is when I run the code it doesnt terminate and shows mw new line each time. Normally also the lines that should be shown are shown, but I dont know where this new lines come, if my file has only a few.

47 Replies

JavaBot•8mo ago

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johnOP•8mo ago

I can post the code also, help appreciated

Unknown User•8mo ago

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johnOP•8mo ago

public class FileIterable implements Iterable<String> {

    //field representing the name of the file
    private final String fileName;

    /**
     * Constructor for creating a new FileIterable object
     *
     * @param fileName name of the text file
     */
    public FileIterable(String fileName) {
        this.fileName = fileName;
    }

    /**
     * Iterates through text file
     *
     * @return Iterator
     */
    @Override
    public Iterator<String> iterator() {
        return new Iterator<String>() {

            //field representing a line
            private String line;

            {
                In.open(fileName);//opening the file
                if (!In.done()) { //checking if file is successfully open
                    throw new UnsupportedOperationException("File could not be opened.");
                }
                line = In.readLine();//reading the line in the file
            }

            /**
             * Checking if there is an another line in the file
             * @return true if there is a next line
             */
            @Override
            public boolean hasNext() {
                return this.line != null;
            }

            /**
             * Returning the next line
             * @return String next line in the file
             */
            @Override
            public String next(){
                if(!hasNext()) { //throwing a exception if there is no next in the file
                    throw new NoSuchElementException("There is no next line.");
                }
                String currentLine = line;
                line = In.readLine(); //reading the next line

                return currentLine.replace("\r", "");
            }
        };
    }

    /**
     * Closes a text file
     */
    public void close() {
        In.close();
    }
}

JavaBot•8mo ago

Please format your code to make it more readable. For java, it should look like this:

```java
public void foo() {
 
}
```

```java
public void foo() {
 
}
```

Unknown User•8mo ago

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johnOP•8mo ago

yes I dont see anything wrong. If I debug it shows my empty strings

Unknown User•8mo ago

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johnOP•8mo ago

yes output:

This is a file
with multiple lines.
It has five lines in total.

The previous was an empty line.

<newline>
<newline>

this lines and than infinitely many new lines even the file has only these

Unknown User•8mo ago

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johnOP•8mo ago

Its in the project included, pre programmed.

Unknown User•8mo ago

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johnOP•8mo ago

Idk I not seeing where the error is.

Unknown User•8mo ago

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johnOP•8mo ago

public static String readLine() {
        StringBuffer b = new StringBuffer();
        char c = read();
        while (done && !LSSTRING.contains(String.valueOf(c))) {
            b.append(c);
            c = read();
        }

        int i = 0;
        while (c == LS[i]) {
            ++i;
            if (i >= LS.length) {
                break;
            }
            c = read();
        }

        if (b.length() > 0) {
            done = true;
        }
        latestValue = b.toString();
        latestMethod = "readLine()";
        return b.toString();
    }

this is the method of readLine But I am not supposed to change anything there this is in In Class

Unknown User•8mo ago

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johnOP•8mo ago

empty string

Unknown User•8mo ago

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johnOP•8mo ago

I know somthing in javadoc but I think the only problem is at my part of the code if I do a "return this.line != null && !line.isEmpty(); " at method hasNext than it works. But the problem is that the file has a empty line which should be displayed

Unknown User•8mo ago

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johnOP•8mo ago

ok i get it

Unknown User•8mo ago

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johnOP•8mo ago

"Depending on the platform/operating system, problems with carriage return (\r) may occur when reading in the file for the FileIterable. To prevent this, you can simply call a line.replace("\r", "") on the line directly when reading in a line, which filters out the carriage return." this is what they said thats why I am using it

Unknown User•8mo ago

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johnOP•8mo ago

public static boolean "Check if the previous operation was successful. This method returns true if the previous read operation was able to read a token of the requested structure. It can also be called after open() and close() to check if these operations were successful. If done() is called before any other operation it yields true"

Unknown User•8mo ago

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johnOP•8mo ago

I dont know that. was just so given to me

Unknown User•8mo ago

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johnOP•8mo ago

hmm. if the string doesnt contains the value of c then... so it checks if the previous call was successful and if c was contained or smth like this so each time should be a different value or I am seeing it wrong

Unknown User•8mo ago

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johnOP•8mo ago

if done returns false

Unknown User•8mo ago

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john•8mo ago

@Override

            public boolean hasNext() {
                return In.done();
            }

            public boolean hasNext() {
                return In.done();
            }

I think i corrected it

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Unknown User•8mo ago

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johnOP•8mo ago

It seems to be working

Unknown User•8mo ago

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johnOP•8mo ago

thank you very much for leading me to the solution

JavaBot•8mo ago

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johnOP•8mo ago

and not that you just said me whats wrong

Unknown User•8mo ago

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johnOP•8mo ago

"if done returns false" somehow

JavaBot•8mo ago

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Unknown User•8mo ago

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johnOP•8mo ago

"public class FileIterable implements Iterable<String>, Autoclosable {". Ok thanks

Unknown User•8mo ago

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johnOP•8mo ago

Ok, thanks!

JavaBot•8mo ago

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Reading lines in a file, but not terminating