[FIXED] Java char[] toString

Issue

I'm playing arround with char[] in Java, and using the folowing sample code:

char[] str = "Hello World !".toCharArray();
System.out.println(str.toString());
System.out.println(str);

I get the following output:

[C@4367e003
Hello World !

And I have some questions about it:

1. What does [C@4367e003 stands for? Is it a memory address? What's the meaning of the digits? What's the meaning of [C@?

2. I always thought that calling println() on an object would call the toString method of this object but it doesn't seems to be the case?

Solution

1. [C means that it's a character array ([ means array; C means char), and @4367e003 means it's at the memory address^[1] 4367e003. If you want a string that represents that character array, try new String(str).

2. println is overloaded; there is also a println that accepts a character array. If you don't pass a primitive, String, or char[], it will then call toString on the object since there's a separate overload for System.out.println(Object). Here is the documentation for the specific method that takes a character array.

   Here are the overloads for println (straight from the docs):

   void println()
   void println(boolean x)
   void println(char x)
   void println(char[] x)
   void println(double x)
   void println(float x)
   void println(int x)
   void println(long x)
   void println(Object x)
   void println(String x)
   

   You can read more about overloading at the bottom of this tutorial.

---

^{[1]: Technically, it's actually the hex representation of the object's hash code, but this is typically implemented by using the memory address. Note that it's not always really the memory address; sometimes that doesn't fit in an int. More info in this quesiton.}

Answered By - tckmn
Answer Checked By - Mary Flores (JavaFixing Volunteer)