Question

I’ve got two arrays:

char[] chars = { '1', '2', '3' };
int[] numbers = { 1, 2, 3 };

Why after calling System.out.print(chars) I’m getting 123 while after System.out.print(numbers) I’ve got smth like [C@9304b1 ?

What is more, after printing System.out.print("abc" + chars) I’m also getting abc[C@9304b1 .

I know that [C@9304b1 equals chars.toString() method but why sometimes System.out.print print only its elements?

Answer 1

PrintStream, the type of System.out, has several overloads for the print method, one of which takes an array of characters (char[]):

public void print(char[] s)

Prints 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.

Thus, in your first example, you get 123 printed. However, PrintStream doesn’t have an overload for print that can accept an int[] as an argument, thus, you end up invoking print(Object), which will use the toString method of an Object, consisting of its type and its hashcode.

In order to print an int[], you can use Arrays.toString() instead.