Java arrays printing out weird numbers and text

Question

I'm new to programming. I'm sure the answer for this question is out there, but I have no idea what to search for.

Ok, I'll go right to it.

Here's my code:

int[] arr;
arr = new int[5];

arr[0] = 20;
arr[1] = 50;
arr[2] = 40;
arr[3] = 60;
arr[4] = 100;

System.out.println(arr);

This compiles and works fine. It's just the output from CMD that I'm dizzy about.

This is the output: [I@3e25a5.

I want the output to represent the exact same numbers from the list (arr) instead. How do I make that happen?

Answer 1

Every object has a toString() method, and the default method is to display the object's class name representation, then @ followed by its hashcode. So what you're seeing is the default toString() representation of an int array. To print the data in the array, you can use:

System.out.println(java.util.Arrays.toString(arr));

Or, you can loop through the array with a for loop as others have posted in this thread.

Answer 2

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

The current output is classtype@hashcode.

Incase you need to print arrays with more than one dimension use:

Arrays.deepToString(arr);

Also remember to override toString() method for user-defined classes so that you get a representation of the objet as you choose and not the default represention which is classtype@hashcode

Answer 3

It's the default string representation of array (the weird text).

You'll just have to loop through it:

for(int i : arr){
System.out.println(i);
}

Answer 4

To print the values use.

for(int i=0; i<arr.length; i++)
   System.out.println(arr[i]);

Answer 5

Like this:

for (int i = 0; i < arr.length; ++i)
{
    System.out.println(arr[i]);
}

That "weird number" is the reference for the array you printed out. It's the default behavior built into the java.lang.Object toString() method.

You should override it in your own objects if seeing the reference isn't sufficient.

Answer 6

It prints it's .toString() method you should print each element

for(int i=0; i<arr.length; i++) {
   System.out.println(arr[i]);
}

or

for(Integer i : arr) {
  System.out.println(i);
}

Answer 7

BTW You can write

int[] arr = { 20, 40, 60, 40, 60, 100 };
System.out.println(Arrays.toString(array));

or even

System.out.println(Arrays.toString(new int[] { 20, 40, 60, 40, 60, 100 }));

or

System.out.println(Arrays.asList(20, 40, 60, 40, 60, 100));

Answer 8

for (int i = 0; i < arr.length; ++i)
{
  System.out.println(arr[i]);
}

Answer 9

Use Arrays.toString() and PrintStream.printf(String format, Object... args).

System.out.printf("%s%n", Arrays.toString(arr));

Answer 10

You printed the reference and not the values at the reference... One day it will all become clear with C.