stephenwade stephenwade - 7 months ago 33
Java Question

Java: println with char array gives gibberish

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

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.