IOException with BufferedReaders and InputStreamReaders

Question

I am modding Minicraft, and I am running into a bit of trouble using BufferedReaders.

So in my mod, I have a class called FuncResource in which I define a way to execute a custom method when an item is used.
In the Resource vanilla class, I define multiple objects of this type. For example, a console object which lets you change your gamemode.
Here is the interact method I am using in the console item class:

public boolean interact(Tile tile, Level level, int x, int y, Player player, int direction)
{
    InputStreamReader isr = new InputStreamReader(System.in);

    BufferedReader reader = new BufferedReader(isr);

    String input = "";

    System.out.print("> ");

    try
    {
        input = reader.readLine();
        reader.close();
    }
    catch(IOException e)
    {
        System.out.println("Input error...  :/");
    }

    String[] commandList = input.split(" ");

    if(commandList[0].equals("gamemode"))
    {
        player.gamemode = Integer.parseInt(commandList[1]);
        return true;
    }

    return false;
}

Now here's the problem: Using the console item once, it's fine. I change my gamemode. HOWEVER, when I use it every time after that, it always throws an IOException. Every single time.

Am I doing something wrong? Have I messed up the input somehow? Please help - I've read the JavaDocs and they didn't help, and I'm an amateur at Java.
If you need more information, just ask.

EDIT: I took people's advice and removed the reader.close(); code. HOWEVER, I tried it again and it printed this stacktrace:

java.io.IOException: Stream closed
    at java.io.BufferedInputStream.getBufIfOpen(BufferedInputStream.java:162)
    at java.io.BufferedInputStream.read(BufferedInputStream.java:325)
    at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:283)
    at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:325)
    at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:177)
    at java.io.InputStreamReader.read(InputStreamReader.java:184)
    at java.io.BufferedReader.fill(BufferedReader.java:154)
    at java.io.BufferedReader.readLine(BufferedReader.java:317)
    at java.io.BufferedReader.readLine(BufferedReader.java:382)
    at com.mojang.ld22.item.resource.funcitems.ConsoleItem.interact(ConsoleItem.java:27)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at com.mojang.ld22.item.resource.FuncResource.interactOn(FuncResource.java:31)
    at com.mojang.ld22.item.ResourceItem.interactOn(ResourceItem.java:53)
    at com.mojang.ld22.entity.Player.attack(Player.java:177)
    at com.mojang.ld22.entity.Player.tick(Player.java:118)
    at com.mojang.ld22.level.Level.tick(Level.java:274)
    at com.mojang.ld22.Game.tick(Game.java:221)
    at com.mojang.ld22.Game.run(Game.java:165)
    at java.lang.Thread.run(Thread.java:744)

Can you post the stack trace that points to the line of code that caused the error? — Taylor Hx, Jan 20 '14 at 02:23
There's lots of reasons it might throw an exception. Have you considered actually printing the exception using something like `e.printStackTrace()` for example — MadProgrammer, Jan 20 '14 at 02:23
Printed the stack trace. I don't know why on Earth it's throwing that error, though... Why would the stream be closed? — Atutouato, Jan 20 '14 at 02:31
Since eventually someone will mention [CloseShieldInputStream](http://commons.apache.org/proper/commons-io/apidocs/org/apache/commons/io/input/CloseShieldInputStream.html) I will go ahead and post a comment :D. Just wrap `System.in` with it and close the `Scanner` as intended. — Anthony Accioly, Jan 20 '14 at 02:38
@AnthonyAccioly, I have no idea what that is. BUT, I will go ahead, look it up, and try to use it anyways. — Atutouato, Jan 20 '14 at 02:40
Actually, @AnthonyAccioly, I want to do this without any external libraries. Sorry. — Atutouato, Jan 20 '14 at 02:43
If you are still getting the exception, verify you aren't closing the stream somewhere else and also make sure you've truly recompiled the code. — Radiodef, Jan 20 '14 at 03:00
I have really truly recompiled the code. `reader` is a local variable, and I have searched and double-searched my file twice over, and there is no reference to the stream being closed. — Atutouato, Jan 20 '14 at 03:10

score 3 · Accepted Answer · answered Jan 20 '14 at 02:24

3

try
{
    input = reader.readLine();
    reader.close();
}
catch(IOException e)
{
    System.out.println("Input error...  :/");
}

Don't close this reader because it contains System.in which should remain open.

answered Jan 20 '14 at 02:24

fgb

18,439
2
38
52

Did you mean to edit this code? Because you're still closing System.in here. – Ernest Friedman-Hill Jan 20 '14 at 02:27
I'm quoting it to comment on it. Of course, `reader.close()` should be removed to fix the code. – fgb Jan 20 '14 at 02:30

score 3 · Answer 2 · answered Jan 20 '14 at 02:25

3

Closing your reader will close the underlying stream; closing System.in is, in general, bad, as you can imagine.

As a general rule, if you opened something, close it; but if you didn't, don't. Here: don't'.

answered Jan 20 '14 at 02:25

Ernest Friedman-Hill

80,601
10
150
186

I tried what you suggested, and it didn't work, but suddenly it did. Thanks! – Atutouato Jan 20 '14 at 03:14

score 0 · Answer 3 · answered Jan 20 '14 at 03:11

0

I cannot remember what I did, but I solved it. I had removed the reader.close(); statement and it still wasn't working properly, but just one time it simply worked. I don't know how or why, but thanks to all who helped.

answered Jan 20 '14 at 03:11

Atutouato

375
4
13

IOException with BufferedReaders and InputStreamReaders

3 Answers3