Creating a byte[] of long size
in [Java Help]
|
Prev: instructor solution manual for Dynamics of Flight- Stability and Control, 3rd Ed by Etkin, Reid
Next: Supply AFF CAPS and hat ( www.nike-black.com )
From: Boris Punk on 8 Jul 2010 16:30 long size = Integer.MAX_VALUE+1; byte [] b = new byte[size]; -possible loss of precision How can we make an array of long size?
From: Eric Sosman on 8 Jul 2010 16:52 On 7/8/2010 4:30 PM, Boris Punk wrote: > long size = Integer.MAX_VALUE+1; > byte [] b = new byte[size]; > > -possible loss of precision > > How can we make an array of long size? Array elements are indexed from [0] through [Integer.MAX_VALUE-1], and that's that. You can make an array whose elements are larger than a single byte (`new long[N]', for example) and thus get an array of more than Integer.MAX_VALUE-1 bytes, but you cannot have more than that many elements. Incidentally, you might want to print the value of `size' that you calculate in your example. It might surprise you ... (By the way: Yes, I really did intend the `-1's above. An int index value could go one higher, but how could you create the array? In `new byte[N]', N cannot exceed Integer.MAX_VALUE, which means that the index cannot exceed N-1, or Integer.MAX_VALUE-1. You could try to write `new byte[] { 0,0,0,... }' and so on for two giga-values, but you'd exceed .class file limits long before you got there.) -- Eric Sosman esosman(a)ieee-dot-org.invalid
From: Eric Sosman on 8 Jul 2010 16:55 On 7/8/2010 4:52 PM, Eric Sosman wrote: > On 7/8/2010 4:30 PM, Boris Punk wrote: >> long size = Integer.MAX_VALUE+1; >> byte [] b = new byte[size]; >> >> -possible loss of precision >> >> How can we make an array of long size? > > Array elements are indexed from [0] through [Integer.MAX_VALUE-1], > and that's that. You can make an array whose elements are larger > than a single byte (`new long[N]', for example) and thus get an array > of more than Integer.MAX_VALUE-1 bytes, but you cannot have more than > that many elements. > [...] > (By the way: Yes, I really did intend the `-1's above.[...] Oh, drat. I really did mean the first one, but not the second. It's been really hot here for the last few days, and my brain is starting to resemble a poached egg. -- Eric Sosman esosman(a)ieee-dot-org.invalid
From: Lew on 8 Jul 2010 17:15 Boris Punk wrote: > long size = Integer.MAX_VALUE+1; > byte [] b = new byte[size]; > > -possible loss of precision > > How can we make an array of long size? > You can't. Why do you want to? From the JLS, which I strongly urge you to study: "The type of each dimension expression within a DimExpr must be a type that is convertible (§5.1.8) to an integral type, or a compile-time error occurs. Each expression undergoes unary numeric promotion (§). The promoted type must be int, or a compile-time error occurs; this means, specifically, that the type of a dimension expression must not be long." 15.10 Array Creation Expressions Didn't you get a compiler error? You can make some other data structure that would hold that much, assuming you have the address space for it. For sure in a 32-bit machine you'd have trouble even with 'new byte [Integer.MAX_VALUE]'. But really, why do you want to? -- Lew
From: Boris Punk on 8 Jul 2010 17:35
Integer.MAX_VALUE = 2147483647 I might need more items than that. I probably won't, but it's nice to have extensibility. |