Java print char array

Question

I run this code and

char[] str = { 'a', 'b', 'c', 0, 'c', 'c', 'f' }; System.out.print(str); System.out.println(" adksjfhak"); 

Prints only "abc". while,

 char[] str = { 'a', 'b', 'c', 0, 'c', 'c', 'f' }; System.out.print(str); System.out.println("\n adksjfhak"); 

prints

 abc adksjfhak 

Why does the print buffer stop with the character NULL (0)? Does this mean that Java just saves an extra character to buffer and print this buffer? And of course, since this buffer has 0 in between, it discards the rest of the line.

Perhaps I answered my question. But I would like to know more about this. Does the Hows JVM handle this? Where is this output buffer? And any reason to stay at 0? Also, why adding \ n stops this behavior?

Edit 1: Using JDK 1.7, Eclipse 3.8.1, and Ubuntu 13.10

Edit 2: Strange, this one doesn't have this problem. https://ideone.com/VwFbRr

Edit 3: I ran the same on the command line

 [bin]$ java com.sakura.C abcccf adksjfhak 

Answer 1

The behavior you see cannot be explained simply by looking at the Java code. Rather, I suspect this is due to what you use to view the output.

First up is:

  char[] str = { 'a', 'b', 'c', 0, 'c', 'c', 'f' }; System.out.print(str); 

According to javadoc PrintWriter

  System.out.print(str); 

will be equivalent to calling

  System.out.print(str[i]); 

for each character. (Yes, everyone, including the null character!). And the write(char) behavior is to simply encode the character according to the default platform encoding and write it. For a null character (zero code point) and a typical 7 or 8 bit encoding that will write the NUL .

On the Java side, there are no funky "zero line-end" facilities with standard Java strings of standard Java I / O classes. Period.

I can think of 3 possible explanations:

• You are wrong. Your real code writes something else. (For example, you may have forgotten to recompile ... if you are testing from the command line.)

• The strange behavior you see is because your console and / or the utility you use to display the output do something special with NUL characters. (However, I don’t remember hearing a console, etc. Program that handled NUL in such a strange way ...)

• Your application has created a custom subtype of PrintWriter that implements some special processing for code zero, and it used System.setOut(...) to redirect output through this class.

---

Having said that, it's probably a good idea to try to print strings or character arrays containing null characters. The NUL character is the "control code" and is usually classified as non-printable. What you see when you try to print is unpredictable.

If you want to continue this, I suggest redirecting the output of the suspect to a file, and then use some (OS-specific) utility to view the bytes of the file; e.g. od on a Unix / Linux system. I would expect to see null bytes in the file ...

Answer 2

Most likely, they all get a "printout" in the operating system in both cases, but in the first case, your operating system or shell accepts the character "0" as a signal so as not to display the rest of the line. In the first case, both lines are displayed on the same line , so the second line is also suppressed. In the second case, the second line is on a new line and therefore displayed.