Why does printing a Java array show a memory location [duplicate]

Question

int[] answer= new int[map.size()];  
HashMap<String, Integer> map = new HashMap<String, Integer>();  

for (int j=0; j<answer.length;j++){  
    int x=map.get(keys.get(j));  
    answer[j]=x;  
}  

return answer  

When I print x using System.out.println(x) in the loop, I get values of 1, 2, 3 but when I return the answer and print it, I get [I@9826ac5. Any idea why?

Answer 1

I[ is kind of the "class type" for an array of integer. Printing out this array itself will print the class type @ then a short hex string because that's the hash code of the array. It's the same as something you've probably seen like Object@0b1ac20. This is implemented as the default toString() for Object.

Maybe you want to return a specific element of the array or print the whole array using a for loop?

Answer 2

Long story short, you can't easily print an array in java. Do this:

System.out.println( Arrays.toString(answer) );

Answer 3

because that is how array's toString() method is implemented