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jmh output prints "??" for average times [duplicate]

I'm trying to do benchmarking with JMH, the benchmarking result did come out but not perfectly
Somehow there's ?? in the numbers, is it the problem with my IDE where I need to set up the settings to show the full numbers or something?

The JMH output makes use of extended Unicode characters. In particular, ? 10?? s/op" probably means "≈ 10⁻¹⁰ s/op".
To solve it
#BenchmarkMode(Mode.AverageTime)
#OutputTimeUnit(TimeUnit.MILLISECONDS)
public class MyBenchmark {

What you are facing is an encoding issue.
JMH by default encodes its output as UTF-8 so instead of those ?? you'll see ± for Error column and e.g. ≈ 10⁻³ for Score column on Linux or Mac.
On Windows Unicode is supported in terminal but not entirely, this is why you see ?? instead of some symbols. To fix this please follow the manual described in another SO question: How to use unicode characters in Windows command line?

Aparapi data types

I have following code for studying.
My calculate function produces unexpected results when runs on aparapi.
Is there any problem with my code, or aparapi?
Results are;
Result Num Expected
2026982348 406816880 40681688012
2026982516 406816881 40681688180
2026982594 406816882 40681688258
2026982662 406816883 40681688326
2026982830 406816884 40681688494
2026982898 406816885 40681688562
2026982966 406816886 40681688630
2026983044 406816887 40681688708
2026983212 406816888 40681688876
2026983280 406816889 40681688944
2026983338 406816890 40681689002
2026983506 406816891 40681689170
2026983584 406816892 40681689248
2026983652 406816893 40681689316
2026983820 406816894 40681689484
2026983888 406816895 40681689552
2026983956 406816896 40681689620
2026984134 406816897 40681689798
2026984202 406816898 40681689866
2026984270 406816899 40681689934
Edit: If I set executionMode JTP or CPU, I get true results (result == expected) but on GPU mode there is a problem. I'm using late 2013 macbook pro retina with windows 10.
Edit2: Return line of my calculate method causes the problem. If I return Long.MAX_VALUE, it works. But (long) tc * 100 (or ((long) tc) * 100) not giving (eg. 40681688900)

I think you should review your code checking against Aparapi Java Kernel Guidelines, expecially paying attention to Other restrictions and Beware Of Side Effects sections.
Remember to keep your code as simpler as you can.
Looking to your code, in the calculate method you make wide use of the modulus (%) operator. I would suggest you to log each calculation in order to be able to compare what you get in JTP mode and what you get in GPU mode, in order to find out if there are some issues with this operator.
EDIT:
In your calculate method you use int variables to hold values, which may hold numbers till 2^31-1, namely 2147483647 as known as Integer.MAX_VALUE.
If you perform int value=2147483647; value++; you will get as a result -2147483648 as known as Integer.MIN_VALUE.
You can alternatively try your program with lower starting numbers or change your variable declarations to long, which may hold Long.MAX_VALUE, namely 2^63-1.
Both long and int values are supported by Aparapi.

Hi I'm the primary maintainer over at the new Aparapi.com and new github repository. We are much more active over at the new project home and even have about a dozen releases in maven central already. You might want to consider moving over to the new Aparapi.
With that said I am a developer at the new Aparapi and ran this test case and confirmed it is a legitimate Aparapi bug. I will look into what is causing the bug and hopefully can get a bug fix in for you before the next release. The issue has been reported here if you would like to track it. Remember this for the new Aparapi project so the bug fix is not likely to show up in the older Aparapi project.

Index Out of Bounds Error

I'm running a simple java program. I programmed it in Netbeans. Everything worked great. Attempted to transition code to use Ant because that's what my class requires, and I'm getting a weird error.
All text coming in from the .txt is in the format,
Baker William Chavez 04/01/05
Sanchez Jose Chavez 06/15/05
etc ...
There about 20 entries, 3 names and a date. Each entry is on its own line.
I'm using this code to read it in.
while ((line = br.readLine()) != null) {
//formatting data correctly
String [] info = line.split(" ");
for(int i = 0; i < info.length; i++){
System.out.println(info[i]);
}
System.out.println(info[0]);
System.out.println(info[1]); /* this line of code */
}
So every info [] is of length 4. When I run the for loop, it prints out everything exactly as expected. Printing out "info[0]" works exactly has expected.
But for some reason when I attempt to print out "info[1]", I get an
java.lang.ArrayIndexOutOfBoundsException: 1
error. I have no explanation for why this happens. When I don't attempt to print out info[1] by itself, my program works correctly. In the for loop, info[1] gets printed out, because the for loop loops through 4 times. This code worked perfectly in Netbeans, but using Ant is doesn't work.
Does anyone know adding or removing just one line,
System.out.println(info[1]);
causes my program to run or throw an exception?
I'm running Ant 1.9.2
I'm running Java 1.7.0_17
I've checked this multiple times, so I'm pretty sure its not something I've made an erro ron. I'm a fairly experienced programmer, so I pretty confident it's not my error. It runs well in Netbeans. I don't have an explanation for the error.
edit 1.
My code throws an error the second time threw the while loop.
Printing out the info[] length, or the line itself works great with I don't print out line[1] by itself. It stills fails and throws an error when I printout the info[1] by itself.
http://pastebin.com/NAUeDsZH
Edit 2.
#Millie Smith was on the right trail because my .txt file wasn't correctly formatted. Viewing it in notepad for some reason didn't display the extra space in between each line.
http://pastebin.com/njjdSHHZ
My correct pastebin.
I was attempting to use code to strip out all of the blank space, commas, new lines, and such,
line = line.replaceAll("\\s+", " ");
line = line.replaceAll(",","");
line = line.replaceAll("\\n", "");
line = line.replaceAll("\\r", "");
String [] info = line.split(" ");
I incorrectly assumed that that code would take care of any irregularities. I was wrong. So on my first pastebin, I formatted the code to what I thought I was dealing with, which was also incorrect.
So if I test for line.length() > 1, that gives me my results that I am looking for. I'm not an experienced programmer as I think I am.

Your last line of the file is BLANK ( probably just a end of line marker ) and this is causing the last .split(" ") to assign a single element array with nothing in it but an empty string in the first position.
Make sure your file doesn't have a ZERO length line as the last line or any of the lines.
Learn to use the step debugger, it is your best friend, and step through the code and see what line is equal to on the very last iteration.
Ant and Netbeans have nothing to do with this error, it is completely data related and we can't see your entire data file in its native format

How to center a print statement text?

So I was working on my java project and in one part of the program I'm printing out text
The text is displayed on the left side
However I wanted it be displayed in the middle
How many I accomplish this?
Is this a newbie question?
Example:
public static void main(String[] args)
{
System.out.println("Hello");
}

VERY QUICK answer
You can use the JavaCurses library to do fun things on the console. Read below it's in there.
Before you do though let's answer your entire question in some context
It is a newbie question :) but it's a valid question. So some hints for you:
First question is, how wide is the terminal? (it's counted in number of characters) old terminals had a fixed dimensions of 80 characters and 25 lines;
So as a first step start with the assumption that it's 80 characters wide.
How would you center a string on an 80 character wide terminal screen?
Do you need to worry about the length of the string? How do you position something horizontally? Do you add spaces? Is there a format string you can come up with?
Once you've written a program such that you can give it any string that will display properly on those assumptions (that terminal is 80 characters wide) you can now start worrying about what happens if you are connected to a terminal which is more or less than 80 characters? Or whether or not you are even connected to a terminal. For example if you are not does it make sense to "prettify" your code? probably not.
So question is how do you get all this information?
What you are asking for is the ability to treat the console as a smart teletype (tty) terminal with character-based control capabilities. Teletype terminals of the old can do a lot of fun things.
Some history
Teletype terminals were complicated things and come from the legacy that there were a lots of terminal manufacturers (IBM, DEC, etc.) ... These teletype terminals were developed to solve lots of problems like being able to display content remotely from mainframes and minicomputers.
There were a bunch of terminal standards vt100, vt200, vt220, ansi, that came about at various points in terminal development history and hundreds of proprietary ones along the way.
These terminals could do positioning of cursors and windowing and colors, highlight text, underline etc. but not everyone could do everything. However this was done using "control" characters. ctrl-l is clear screen on ansi and vt terminals, but it may be page feed on something else.
If you wrote a program specific to one it would make no sense elsewhere. So the necessity to make that simple caused a couple of abstraction libraries to developed that would hide away the hideousness.
The first one is called termcap (terminal-capabilities) library, circa 1978, which provided a generic way to deal with terminals on UNIX systems. It could tell a running program of the available capabilities of the terminal (for example the ability to change text color) or to position cursor at a location, or to clear itself etc, and the program would then modify its behavior accordingly.
The second library is called curses, circa 1985 (??) it was developed as part of the BSD system and was used to write games ... One of the most popular versions of this library is the GNU curses library (previously known as ncurses).
On VMS I believe the library is called SMG$ (screen management library).
On with the answer
Any how, so you can use one of these libraries in java to determine whether or not you are working on a proper terminal. There is a library called JavaCurses on source forge that provides this capability to java programs. This will be an exercise in learning how to utilize a new library into your programs and should be exciting.
JavaCurses provides terminal programming capability on both Unix and Windows environments. It will be a fun exercise for you to see if you can use it to play with.
advanced exercise
Another exercise would be to use that same library to see if you can create a program that display nicely on a terminal and also writes out to a text file without the terminal codes;
If you have any issues, post away, I'll help as you go along.

If you have a definite line length, apache commons StringUtils.center will easily do the job. However, you have to add that library. javadoc

Java print statements to the console can't be centered as there is no maximum width to a line.
If your console is limited to, for example, 80 chars, you could write a special logger that would pad the string with spaces.
If your string was greater than 80 chars then you would have to cut the string and print the remainder on the next line. Also, if someone else was using your app with a console with a different width (especially smaller) if would look weird.
So basically, no, there is no easy way to center the output...

You could do something like:
public static void main(String[] args) {
String h = "Hello";
System.out.println(String.format("%-20s", h));
}
This approach outputs a string offset by a given number of spaces. In this case Hello is preceded by 20 spaces. The spaces precede Hello because the integer between % and s is negative, otherwise the spaces would be trailing.
Just mess with the integer between % and s until you get the desired result.

As lot of programming questions, dont reinvent the wheel!
Apache have a nice library: "org.apache.commons" that come with a StringUtils class:
https://commons.apache.org/proper/commons-lang/apidocs/org/apache/commons/lang3/StringUtils.html
The pad method is what you want:
int w = 20;
System.out.println(StringUtils.rightPad("+", w - 1, "-") + "+");
System.out.println(StringUtils.center(StringUtils.center("output", w - 2), w, "|"));
System.out.println(StringUtils.rightPad("+", w - 1, "-") + "+");
will give you:
+----------------------+
| output |
+----------------------+

You can't. You are writing to the console which does not have a width so the center is undefined.

If you know the size and don't want to use an external library you could do something like this:
static void printer(String str, int size) {
int left = (size - str.length()) / 2;
int right = size - left - str.length();
String repeatedChar = "-";
StringBuffer buff = new StringBuffer();
for (int i = 0; i < left; i++) {
buff.append(repeatedChar);
}
buff.append(str);
for (int i = 0; i < right; i++) {
buff.append(repeatedChar);
}
// to see the end (and debug) if using spaces as repeatedChar
//buff.append("$");
System.out.println(buff.toString());
}
// testing:
printer("string", 30);
// output:
// ------------string------------
If you call it with an odd number for the size variable, then it would be with one - more to the right. And you can change the repeatedChar to be a space.
Edit
If you want to print just one char and you know the size, you could do it with the default System.out.printf like so:
int size = 10;
int left = size/2;
int right = size - left;
String format = "%" + left + "c%-" + right + "c";
// would produce: "%5c%-5c"
System.out.printf(format,' ', '#');
// output: " # " (without the quotes)
The %-5c align the # character to the left of the 5 spaces assigned to it

Printing very big BigIntegers

I'm trying to figure out the following issue related to BigIntegers in Java 7 x64. I am attempting to calculate a number to an extremely high power. Code is below, followed by a description of the problem.
import java.math.BigInteger;
public class main {
public static void main(String[] args) {
// Demo calculation; Desired calculation: BigInteger("4096").pow(800*600)
BigInteger images = new BigInteger("2").pow(15544);
System.out.println(
"The number of possible 16 bpc color 800x600 images is: "
+ images.toString());
}
}
I am encountering issues printing the result of this operation. When this code executes it prints the message but not the value of images.toString().
To isolate the problem I started calculating powers of two instead of the desired calculation listed in the comment on that line. On the two systems I have tested this on, 2^15544 is the smallest calculation that triggers the problem; 2^15543 works fine.
I'm no where close to hitting the memory limit on the host systems and I don't believe that I am even close to the VM limit (at any rate running with the VM arguments -Xmx1024M -Xms1024M has no effect).
After poking around the internet looking for answers I have come to suspect that I am hitting a limit in either BigInteger or String related to the maximum size of an array (Integer.MAX_VALUE) that those types use for internal data storage. If the problem is in String I think it would be possible to extend BigInteger and write a print method that spews out a few chars at a time until the entire BigInteger is printed, but I rather suspect that the problem lies elsewhere.
Thank you for taking the time to read my question.

The problem is a bug of the Console view in Eclipse.
On my setup, Eclipse (Helios and Juno) can't show a single line longer than 4095 characters without CRLF. The maximum length can vary depending on your font choice - see below.
Therefore, even the following code will show the problem - there's no need for a BigInteger.
StringBuilder str = new StringBuilder();
for (int i = 0; i < 4096; i++) {
str.append('?');
}
System.out.println(str);
That said, the string is actually printed in the console - you can for instance copy it out of it. It is just not shown.
As a workaround, you can set Fixed width console setting in Console preferences, the string will immediatelly appear:
The corresponding bugs on Eclipse's bugzilla are:
Display problem in console when a line reaches 4096 characters
Texteditor can't show a line with more than 4095 chars. Limit at 4096 chars.
Long lines are not displayed by editor
According to those, it's a Windows/GTK bug and Eclipse's developers can't do anything about it.
The bug is related to the length of the text is pixels, use a smaller
font and you will be able to get more characters in the text before it
breaks.