Thread: Java error discovered?

The problem is near the end - "Files.write(file1, charArray);" - only prints 1 line to the file. Tried 3 different ways of printing to file. This must be an error with Java.

import java.io.*;
import java.nio.file.*;
import java.nio.charset.Charset;
 
public class alphabetizer {
 
	public static void main(String[] args) {
 
 
		File file = new File("C:\\Documents and Settings\\Administrator\\My Documents\\unsorted_list.txt");
		File file2 = new File("C:\\Documents and Settings\\Administrator\\My Documents\\sorted_list.txt");
		StringBuffer contents = new StringBuffer();
		BufferedReader reader = null;
		BufferedReader reader1 = null;
		int count = 0;
		int listlength = 0;
		String[] list = null;
		String temp1 = null;
		Path file1 =  FileSystems.getDefault().getPath("C:\\Documents and Settings\\Administrator\\My Documents\\", "sorted_list.txt");
		byte[] charArray;
 
		try {
       	       		reader = new BufferedReader(new FileReader(file));
			reader1 = new BufferedReader(new FileReader(file));
	       		String text = null;
 
		        // repeat until all lines are read
 
            		while ((text = reader.readLine()) != null) {
		                contents.append(text).append(System.getProperty("line.separator"));
				count++;
            		}
 
			list = new String[count];	
			count = 0;
 
			while ((temp1 = reader1.readLine()) != null) {
              			list[count] = temp1;
				count++;
            		}
 
			listlength = count;
 
        	} catch (FileNotFoundException e) {
            		e.printStackTrace();
        	} catch (IOException e) {
            		e.printStackTrace();
        	} finally {
            		try {
                	     if (reader != null) {
                             reader.close();
                        }
           	} catch (IOException e) {
               	        e.printStackTrace();
                       }
       		}
 
		count = 0;
		int count1 = 0;
		String temp = null;
		String temp2 = null;
		String temp3 = null;
 
 
		for ( count = 0 ; count < listlength ; count++ ) {	
			temp = list[count];
			for ( count1 = 0 ; count1 < count ; count1++ ) {	
 
				temp2 = list[count1].toLowerCase(); 
				temp3 = list[count].toLowerCase();
 
				if ( (temp2.indexOf(45) == -1) && (temp3.indexOf(45) == -1) ) {
 
					if ( temp2.compareTo(temp3) > 0) {
 
					temp = list[count];
					list[count] = list[count1];
					list[count1] = temp;
					count1++;
					}	
 
				} else {
 
					if (temp2.indexOf(45) != -1) {
						temp2 = list[count1].substring(0, list[count1].indexOf(45)).toLowerCase();
						//System.out.println(list[count]);
					} else {
						temp2 = list[count1].toLowerCase();
					}
 
					if (temp3.indexOf(45) != -1) {
						temp3 = list[count].substring(0, list[count].indexOf(45)).toLowerCase();
					} else {					
						temp3 = list[count].toLowerCase();
					}
 
					if ( temp2.compareTo(temp3) > 0) {
 
						temp = list[count];
						list[count] = list[count1];
						list[count1] = temp;
						count1++;
 
					}
				}
 
			}
 
 
		} 	
 
		String temp5;
 
		try {
 
			for (int i = 0 ; i < listlength ; i++) {
 
				//System.out.println(list[i]);
				charArray = list[i].getBytes();
				temp5 = new String(charArray);
 
 
				//System.out.println(temp5);
 
				Files.write(file1, charArray);	
 
			}
 
		}  catch (IOException e) {
			System.out.println("IOException occurred");
		}	
 
 
 
 	       // show file contents here
       	       //System.out.println(contents.toString());	
 
 
 
	}	
 
}

I'm not entirely sure what your code is suppose to do. More likely than not, though, this is not a bug in Java, but an issue with your program. I can see several odd practices in your Java code.

What is your program suppose to do? Do you have sample input files along with expected output vs. what you're getting (preferably something as short as possible which still demonstrates the issue)?

The program takes a list of names and puts them in alphabetical order. I can tell you for sure, that everything works except for the printing to a file. Those commented out System.out.prints show that the list is fully alphabetized. When the file is printed out - all it shows is one name of the 397.

I just tried it with a new list of 10 names - for some reason, the alphabetizing didn't work, nevertheless, the problem is the same - I can't write to file. Just copy all that up there to a file called alphabetizer.java (I can't attach files with this), and then I put this random list of names to a file, list_of_names.txt :

Benita Abner
Reed Kellam
Jordon Seth
Brittany Hellard
Cyndi Liddle
Princess Pickell
Audrie Ehle
Luvenia Pipes
Astrid Rother
Hermina Withers

The file shows up in My Documents - but only the last line is present. You just need to change these 3 directories:

File file = new File("C:\\Documents and Settings\\Administrator\\My Documents\\unsorted_list.txt");
File file2 = new File("C:\\Documents and Settings\\Administrator\\My Documents\\sorted_list.txt");
Path file1 = FileSystems.getDefault().getPath("C:\\Documents and Settings\\Administrator\\My Documents\\", "sorted_list.txt");

It's a common reaction to "blame Java" when something unfamiliar happens. But think about it this way: which is more likely: you discovering a flaw that nobody else has found in a common API used by millions of people? Or that you just don't fully understand what the code is doing?

I'm not trying to come off as judgmental, but it's a good practice to always blame yourself first: what am I misunderstanding here? What did I miss?

I'd recommend you step through this with a debugger, or at least add some print statements, to figure out what's going on. Read through the APIs of everything you're using to make sure you aren't incorrectly assuming something. If you still can't figure it out, I suggest putting together an SSCCE that demonstrates exactly what you're talking about in as few lines as possible (which, in your case, should only be a few).

Try abstracting your code. Break it up into smaller methods which each perform one task (for example, have a method which reads the file in, another one which takes a list of names and sorts them, and a third one which writes the file out). This will help you to analyze each section independent of the others to determine if they work as expected. It will also make your code much easier to read and decipher.

There are a few things you can get rid of. For example, this:

listlength = count;

Arrays already have a length field (this isn't C or C++ where you need to track length separately). Use that instead. You don't need to manually set it or anything, it's automatically set when you create the array.

As far as writing to a file goes, try using a PrintStream. This is the same output mechanism used by System.out and System.err and is my personal favorite for generic file output.

Try what I suggested: abstract your code into separate methods.

To write multiple lines to a file:

public static void write_file(String filename) throws FileNotFoundException
{
	PrintStream out = new PrintStream(new FileOutputStream(filename));
	out.println("first line.");
	out.println("second line.");
	out.println("third line.");
}

This prints out 3 lines of text to a given file. For example,

public static void main(String[] args)
{
	try
	{
		write_file("test.txt");
	}
	catch (FileNotFoundException e)
	{
		// TODO Auto-generated catch block
		e.printStackTrace();
	}
}

Works perfectly fine for me. I'm running Windows 7, 64-bit with Java 1.7.0_03-b05.

Originally Posted by Programming_Hobbyist

Yes, a genuine Java error discovered. Printing to file doesn't work if you use a for loop to do it - the problem is the Try statement. It only allows runs once for instance - the last one. Thus - I've got to write the file all in one shot - if that's even possible.

I'll contact Sun and Oracle.

Are you being sarcastic? I promise that this is not an actual bug- you're just misunderstanding something. Please post an SSCCE that demonstrates exactly what you're talking about in as few lines as possible.

There are channels to report bugs, and they'll need an SSCCE as well, so you might as well let us check it over for you.

Try saving the following to testing.java. You'll see it writes to the file - but it only writes one line instead of 10. It does that with the three different methods of writing to a file that I've found. I'll send this error in Java's code to Sun/Oracle.

import java.io.*;
import java.nio.file.*;
import java.nio.charset.Charset;
import static java.nio.file.StandardCopyOption.*;
 
 
 
public class testing {
 
	public static void main (String[] args) {
 
		Path file = FileSystems.getDefault().getPath("C:\\Documents and Settings\\Administrator\\My Documents\\", "sorted_list_1.txt");  
		String temp = "hello";
		byte[] chararray;
		chararray = temp.getBytes();
 
		try {
			for ( int i = 0 ; i < 10 ; i++ ) {
 
				//System.out.println(temp5);
				Files.write(file, chararray);	
 
			}
 
		}  catch (IOException e) {
			System.out.println("IOException occurred");
		}	
 
 
	}
 
}

Originally Posted by Programming_Hobbyist

I didn't try that - I didn't need to. I need to write hundreds of lines to a file.

It's meant to be a short demonstration, it isolates the issue purely to file writing.

	public static void write_file(String filename) throws FileNotFoundException
	{
		PrintStream out = new PrintStream(new FileOutputStream(filename));
		for (int i = 0; i < 1000000; ++i)
		{
			out.println(i + " line.");
		}
	}

This piece of code writes a million lines to a file using a for loop. Again, I have no problems.

edit:

I figured out what you're doing wrong. Relevant Javadoc:

Writes bytes to a file. The options parameter specifies how the the file is created or opened. If no options are present then this method works as if the CREATE, TRUNCATE_EXISTING, and WRITE options are present. In other words, it opens the file for writing, creating the file if it doesn't exist, or initially truncating an existing regular-file to a size of 0. All bytes in the byte array are written to the file. The method ensures that the file is closed when all bytes have been written (or an I/O error or other runtime exception is thrown). If an I/O error occurs then it may do so after the file has created or truncated, or after some bytes have been written to the file.

Your file code isn't appending because you never specified that it should append. Rather, you're continually opening up the file, truncating the file to 0 size, writing to it, closing the file, then repeating the process.

see the edit to my response... it shows that this isn't a problem in Java, just a misunderstanding of what Files.write() does.

Originally Posted by Programming_Hobbyist

Yes the problem is the Try/Catch statement. Throws solves it. Problem solved - but it's still an error.

No, it isn't an error, and you're wrong that it has anything to do with the try, catch, or throw statement. This works fine for me too:

	public static void write_file(String filename)  
	{
		try{
			PrintStream out = new PrintStream(new FileOutputStream(filename));
			for (int i = 0; i < 1000000; ++i)
			{
				out.println(i + " line.");
			}
		}
		catch(FileNotFoundException e){
			e.printStackTrace();
		}
	}

If you really want to convince us, provide an SSCCE - take out all your extra logic and concentrate only on the issue at hand, as helloworld and I did.

Chances are you're either misunderstanding the API or your code is doing something different from what you assume it's doing. The only way to be sure is to put together a little example.

I stand by my statement that this is almost definitely not a "Java error". You've listed several sources of potential human error, and nobody (including you) is able to reproduce your original problem. This is exactly why we ask for an SSCCE- it forces you to check all of your assumptions, including about which version of your own code you're running.

I would guess that the ghost in your machine is in fact a result of some misunderstanding about what the code was doing, and then a misunderstanding about which code you were actually running. Again, not a Java error. This is why I suggested that you shouldn't jump to that conclusion before checking all of your assumptions.

Originally Posted by Programming_Hobbyist

Helloworld992 helped me figure it out - there's something wrong with .write. There's something call the scientific method. If something is obviously wrong - you tend to accept that as fact.

Hahahaha, no, you tend to try to repeat the experiment! If you (and others) can't repeat the results, then something must have been wrong with your original findings. In this case, you made an error in the code or in your assumptions. And that's fine, it happens to every single one of us, which is why it's not very wise to conclude that you found a major bug in Java every time.