4 ms·

Seriously? You've never read from or written to a stream?

by cbsmith 13y ago

smrtinsert 13y ago
Where does HN find these guys... It's amazing how many long term "java" developers there are here.
- cbsmith 13y ago
  I honestly am at a loss for this. Reading & writing data from a stream without losing any information seems like a pretty basic thing you'd want to know how to do in your chosen programming language.
  - peterashford 13y ago
    The reason for this is that if you're doing IO in Java you'll usually use some kind of buffered input reader rather than stdio. I've written a command line in Java that reads commands, runs native commands, streams output to the console and even that doesn't need to read stdio as a stream. It's not that Java can't do that, it's that there are better idioms for most problems.
    - cbsmith 13y ago
      > The reason for this is that if you're doing IO in Java you'll usually use some kind of buffered input reader rather than stdio. The methods are the same with a buffered input reader. > I've written a command line in Java that reads commands, runs native commands, streams output to the console and even that doesn't need to read stdio as a stream. So, the thing that you are struggling with is how to get to System.in? But no problem doing System.out? That's not even what the various code samples that have been posted have failed. > It's not that Java can't do that, it's that there are better idioms for most problems. Java's actually very good at doing IO efficiently, and as has been demonstrated, the code for this is quite simple. Sure, you wouldn't implement "cat" in Java, but you would read and write to sockets & files with it, which provides all the knowledge one might need to figure out how to solve this. As has been pointed out, the Apache Commons libraries make it so this is a two line program with no branching or looping. That's about as simple as it gets.
      - peterashford 13y ago
        I'm not struggling with it at all. I'm an ex C,C++ programmer, i'd do a while not eof read loop.
deleted 13y ago
[deleted]
lmm 13y ago
I've never copied one stream to another by hand, byte by byte. There's a method in one of the apache commons libraries for that. But most of the time the only reason I'd ever read an input stream is using a CSV parser or a JSON parser or the like, in which case the idiom is usually to just hand the stream to the parser.
- cbsmith 13y ago
  > I've never copied one stream to another by hand, byte by byte. Yeah, but you've probably done a read and write independently. This is just about joining the two together. > There's a method in one of the apache commons libraries for that. Yup, and that's great to use that, and you'll no doubt end up with more efficient code most of the time if you do. But... you still should be able to write correct code for reading bytes from one stream, writing to another, without losing data in between.
  - lmm 13y ago
    > you still should be able to write correct code for reading bytes from one stream, writing to another, without losing data in between. With access to Google and the library documentation sure, but I don't use those APIs often enough to be worth keeping in memory.
    - cbsmith 13y ago
      > With access to Google Why the heck would you need Google > and the library documentation It's an online quiz. > sure, but I don't use those APIs often enough to be worth keeping in memory. You don't worry about it, but it tends to accumulate in one's mind anyway. Here's the thing though. People are posting solutions on HN... and getting it wrong.
cs02rm0 13y ago
Of course. These days though I don't tend to get much closer than something like Properties.load(InputStream). I really would have had to think about it. I guess I've been stuck in webapps and NoSQL libraries for a while now.

Seriously? You've never read from or written to a stream?

by cbsmith 13y ago

Seriously? You've never read from or written to a stream?

smrtinsert 13y ago

Where does HN find these guys... It's amazing how many long term "java" developers there are here.

cbsmith 13y ago
I honestly am at a loss for this. Reading & writing data from a stream without losing any information seems like a pretty basic thing you'd want to know how to do in your chosen programming language.
- peterashford 13y ago
  The reason for this is that if you're doing IO in Java you'll usually use some kind of buffered input reader rather than stdio. I've written a command line in Java that reads commands, runs native commands, streams output to the console and even that doesn't need to read stdio as a stream. It's not that Java can't do that, it's that there are better idioms for most problems.
  - cbsmith 13y ago
    > The reason for this is that if you're doing IO in Java you'll usually use some kind of buffered input reader rather than stdio. The methods are the same with a buffered input reader. > I've written a command line in Java that reads commands, runs native commands, streams output to the console and even that doesn't need to read stdio as a stream. So, the thing that you are struggling with is how to get to System.in? But no problem doing System.out? That's not even what the various code samples that have been posted have failed. > It's not that Java can't do that, it's that there are better idioms for most problems. Java's actually very good at doing IO efficiently, and as has been demonstrated, the code for this is quite simple. Sure, you wouldn't implement "cat" in Java, but you would read and write to sockets & files with it, which provides all the knowledge one might need to figure out how to solve this. As has been pointed out, the Apache Commons libraries make it so this is a two line program with no branching or looping. That's about as simple as it gets.
    - peterashford 13y ago
      I'm not struggling with it at all. I'm an ex C,C++ programmer, i'd do a while not eof read loop.

deleted 13y ago

[deleted]

lmm 13y ago

I've never copied one stream to another by hand, byte by byte. There's a method in one of the apache commons libraries for that. But most of the time the only reason I'd ever read an input stream is using a CSV parser or a JSON parser or the like, in which case the idiom is usually to just hand the stream to the parser.

cbsmith 13y ago
> I've never copied one stream to another by hand, byte by byte. Yeah, but you've probably done a read and write independently. This is just about joining the two together. > There's a method in one of the apache commons libraries for that. Yup, and that's great to use that, and you'll no doubt end up with more efficient code most of the time if you do. But... you still should be able to write correct code for reading bytes from one stream, writing to another, without losing data in between.
- lmm 13y ago
  > you still should be able to write correct code for reading bytes from one stream, writing to another, without losing data in between. With access to Google and the library documentation sure, but I don't use those APIs often enough to be worth keeping in memory.
  - cbsmith 13y ago
    > With access to Google Why the heck would you need Google > and the library documentation It's an online quiz. > sure, but I don't use those APIs often enough to be worth keeping in memory. You don't worry about it, but it tends to accumulate in one's mind anyway. Here's the thing though. People are posting solutions on HN... and getting it wrong.

cs02rm0 13y ago

Of course. These days though I don't tend to get much closer than something like Properties.load(InputStream). I really would have had to think about it. I guess I've been stuck in webapps and NoSQL libraries for a while now.