为什么java中的数组大小有最大限制？

Question

I got to find from Do Java arrays have a maximum size? that there is a maximum limit for array size .

May be with the intention that it might deplete heap space . Yes, I agree with the point .

I cannot understand the following :

1. But why to have this limit for every single array ?

2. what if I have a number of arrays of such large size ?

3. why not throw an exception when some threshhold of heap space is reached overall(total consumption) , instead of having upperbound for each array ?

Note :

1. In Python, they have this limit How Big can a Python Array Get?

2. In C , there seems like no limit (except the hardware used) The maximum size of an array in C

Answer 1

Arrays in java are indexed by int values. So even if you have infinte memory, the max no. of elements an array can hold is 2^31-1 (Please correct me if I am wrong with the number... but you get the idea).

However, your memory will limit you on how many such large arrays you can keep in your heap...

Answer 2

The length of an array is an int , so you can't allow arrays with more than Integer.MAX_VALUE elements without breaking length . Breaking length would be huge; it would require source changes and recompilation all over the place.

Given that you already have a length cap mandated by the length field, there's not a huge difference between a cap of Integer.MAX_VALUE or something like Integer.MAX_VALUE - 5 .

Answer 3

Lets say if you have a array

String[] array = new String[22L];

Error message in eclipse

Type mismatch: cannot convert from long to int 

Clearly tells that the size of array takes int for length which is limited by ** max int value which is limited by 32-bits**