数组内部的数组-Java

Question

Ok, so I have a 2D array that returns an array.

Object[][] sample = new Object[1][1];
//ok just imagine sample already has an array inside of it

How do I retrive the array within the 2d array?

I have tried to create a new array with the value,

object[] = sample[0][0];

but it just creates an error.

When I print the value of

sample[0][0]

it returns the value: [[Ljava.lang.Object;@4e25154f

I do not know how to solve this.

Answer 1

sample[0][0] returns the object not int. First you need to downcast it and then retrieve integer value

For example :-

CustomObject co = (CustomObject)sample[0][0]; // downcast here

then retrieve the required field from your custom object

Answer 2

sample[0][0] is Object not int[] , sample[0] can be one dimensional array or any Object , note that arrays are also Object in java.

To print multidimensional array you can use Arrays.deepToString(twoDarray) but this does not work if you have stored specifically Object .

Moreover, [[Ljava.lang.Object;@4e25154f is the result of default toString representation of the Object stored at sample[0][0] which is I think an array . To print array you can use Arrays.toString(int[]) .

I guess this is what you are trying to do,

Object[][] obj = new Object[1][1];
obj[0][0] = new int[]{0,1,0,2};
System.out.println(obj);
//To get int[]
int[] arr= (int[]) obj[0][0];//Need to cast to the int[] specifically
//because it's currently stored as an Object
System.out.println(Arrays.toString(arr));

OUTPUT

[[Ljava.lang.Object;@1db9742
[0, 1, 0, 2]