Strange behavior with System.out.println

Question

I was working with the following code:
1. public class DemoChar {
2. public static void main(String args[]) {
3.
4. char buf[] = new char[50];
5. buf[0] = 'a';
6. buf[1] = 'b';
7. buf[2] = 'c';
8. buf[3] = 'd';
9. buf[4] = 'e';
10. System.out.println( buf);
11. }
12. }
if you print "buf", it really works; however if you change line 10 by :
System.out.println("--->" + buf );
The method "println()" doesn't write "--->abcde". The functionality doesn't the same. It will appear "----> [C@3e25a5"
Could you help me?
I don't understand that behavior. I am using "java version 1.6.0_07"

Answer 1

buf's an array and thus is an object. object's don't inherently know how to represent themselves as Strings, so you have to do other things to make sure that they print out ok. To get a char array to print well, you could use the String method valueOf(...):
public class DemoChar
  public static void main(String args[])
    char buf[] = {'a', 'b', 'c', 'd', 'e'};
    System.out.println(buf);  // this seems to call implicitly String.valueOf(buf)
    System.out.println("--->" + buf);  // this however seems to call buf.toString() with different results
    System.out.println("--->" + String.valueOf(buf));
}Also, when posting your code, please use code tags so that your code will retain its formatting and be readable. To do this, you can will need to paste already formatted code into the forum, highlight this code, and then press the "code" button at the top of the forum Message editor prior to posting the message. You may want to click on the Preview tab to make sure that your code is formatted correctly. Another way is to place the tag [code] at the top of your block of code and the tag [/code] at the bottom, like so:
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{code}Edited by: Encephalopathic on Aug 21, 2008 9:40 AM