Java: println with char array gives gibberish

Question

Here's the problem. This code:

String a = "0000";  System.out.println(a); char[] b = a.toCharArray();  System.out.println(b); 

returns

 0000 0000 

But this code:

String a = "0000";  System.out.println("String a: " + a); char[] b = a.toCharArray();  System.out.println("char[] b: " + b); 

returns

 String a: 0000 char[] b: [C@56e5b723 

What in the world is going on? Seems there should be a simple enough solution, but I can't seem to figure it out.

Answer 1

When you say

System.out.println(b); 

It results in a call to print(char[] s) then println()

The JavaDoc for print(char[] s) says:

Print an array of characters. The characters are converted into bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of the write(int) method.

So it performs a byte-by-byte print out.

When you say

System.out.println("char[] b: " + b); 

It results in a call to print(String), and so what you're actually doing is appending to a String an Object which invokes toString() on the Object -- this, as with all Object by default, and in the case of an Array, prints the value of the reference (the memory address).

You could do:

System.out.println("char[] b: " + new String(b)); 

Note that this is "wrong" in the sense that you're not paying any mind to encoding and are using the system default. Learn about encoding sooner rather than later.