printstream « API « Java I/O Q&A

1. PrintWriter and PrintStream never throw IOExceptions

Some days ago I realized that PrintWriter (as well as PrintStream) never throw an IOException when writing, flushing or closing. Instead it sets an internal flag (trouble=true) when ...

2. Java - Capturing System.err.println or Capturing a PrintStream

Java Newbie question : I need to capture the text being written to a printStream by a 3rd party component. The PrintStream is defaulted to System.err, but can be changed to another PrintStream. Looking ...

3. Why does PrintStream.close() end up getting called twice?

Somewhat to my surprise, the following code prints out "Close" twice. Running through the debugger, it seems MyPrintStream.close() calls super.close(), which ends up calling MyPrintStream.close() again.


public ...

4. Java: How do I read from PrintStream?

I am trying to read(append incoming data into a local String) from a PrintStram in the following code block:

    System.out.println("Starting Login Test Cases...");

 out = new PrintStream(new ByteArrayOutputStream());

5. Java: PrintStream to String?

I have a function that takes an object of a certain type, and a PrintStream to which to print, and outputs a representation of that object. How can I capture this ...

6. Java: Difference between PrintStream and PrintWriter

What is the difference between PrintStream and PrintWriter? They have much methods in common. I always mix up this classes because of that reason. And I think we can use them ...

7. On system.out, clarification needed

I was looking at someone's code and saw that he repeatedly declared

PrintStream out = System.out;
and later called
I actually thought this was kind of neat. Is this a common practice? Was he ...

8. How to extract content that is sent to a PrintStream?

Im using a thirdparty class that has the following method:

public void print(PrintStream s);
But what I want to do is acually log the output. SOmething like:
RecordingPrintStream p = new RecordingPrintStream
So what can ...

9. printstream & printwriter

how come System.out.println() method prints character on the screen when out is of type print stream which is used to display bytes

10. PrintWriter autoflush puzzling logic

public PrintWriter(OutputStream out, boolean autoFlush):

out - An output stream
autoFlush - A boolean; if true, the println, printf, or format methods
will flush the output buffer
public PrintStream(OutputStream out, boolean ...

11. Writer or PrintStream that expands tab chars into spaces at set tab stops

Id like a simple class lets call it Printer that supports richer formatting in addition to limiting decimal number places for doubles etc.

interface Printer {
   void print(CharSequence c);
Some interesting ...

12. Why don't we close `System.out` Stream after using it?

I just want to know, we usually close streams at the end, but why don't we close System.out PrintStream with System.out.close()?

13. Do I have to close FileOutputStream which is wrapped by PrintStream?

I'm using FileOutputStream with PrintStream like this:

class PrintStreamDemo {  
  public static void main(String args[]){ 
   FileOutputStream out; 
   PrintStream ps; // declare a print ...

14. Read a PrintStream!

Ok, did I a search here but no real luck. I have this class that as one of the parameters accepts a PrintStream (apparently, since the example uses System.out, which is a PrintStream obj). Now, how do I read this PrintStream obj? The idea here is ofcource not to use System.out, but an object from where I can then examine the ...

15. How to create PrintStream using PrintWriter

Hello, I have an interesting problem. I have two instances of PrintWriter (one for out and other for err) in a particular method. In that method, I am loading one more class using class loader and executing a particular method (lets call this as LoadedClass ublic static void main(String[] args) method. Now, whatever output generated by LoadedClass ublic static void main(String[] ...

16. differents between PrintWriter and PrintStream

The principal difference between using the ...Stream classes and the ...Reader/...Writer classes is that the former deal with raw bytes, while the latter deal with characters. Dealing with characters requires that specific "character encoding" be specified; Unicode in its various shapes (UTF-8, UTF-16, ...) is one such encoding. If you looks at the javadocs for PrintStream.print you'll see that it uses ...

17. PrintStream problems

Hi, I'm having problems with PrintStreams. I've created a program which reads and writes data on a socket, using BufferedReader and PrintStreams. If there is data going both ways it works okay. If there is data to send but none to receive i keep getting intermittent errors when i try writing to the socket. Below is a test program that i've ...

18. what is the difference between printStream and PrintWriter?

public class PrintStream extends FilterOutputStream A PrintStream adds functionality to another output stream, namely the ability to print representations of various data values conveniently. Two other features are provided as well. Unlike other output streams, a PrintStream never throws an IOException; instead, exceptional situations merely set an internal flag that can be tested via the checkError method. Optionally, a PrintStream can ...

19. PrintStream class

Single quotes (like this: 'c' ) in Java do not mean a String -- they mean a character constant. The type of a character constant is char, and char is just an unsigned 16-bit integer. '\n' is a special character constant that stands for the newline character; the Unicode value is 10 . You can always assign a narrower integral value ...

20. Dataoutputstream VS printstream

21. PrintStream & PrintWriter

22. PrintStream file manipulation

I was just wondering is there anyway to use printStream without overriding the content that is previous stored within a file. for example if i have a file that I previously written content to and now want to read in the same file to manipulate again using a PrintStream object overrides what was previous written. How can i afford this?

23. Custom terminator for PrintStream

24. PrintStream

I've set up a PrintStream: PrintStream p = new PrintStream(outFile); and whenever I use p.println(string). In the output file it prints OD once its printed the given string. I've used a printstream many times before and this has never happened. Can anyone tell my why this is happening and how I can fix it?

25. Why System.out.println not PrintStream.println ?

According to the api: A PrintStream adds functionality to another output stream, namely the ability to print representations of various data values conveniently. Two other features are provided as well. Unlike other output streams, a PrintStream never throws an IOException; instead, exceptional situations merely set an internal flag that can be tested via the checkError method. Optionally, a PrintStream can be ...

26. Can you make it clear how 'System.out' is able to instantiate PrintStream?

I tried my best to create a class variable and then instantiate it with PrintStream class, but, the only way to do it is: static PrintStream myObj; myObj = new PrintStream(System.out); Can you make it clear how 'System.out' is able to instantiate PrintStream class so that i instantiate my class variable myObj in same way?

27. printStream.println

28. PrintStream and PrintWriter

Hi, Could anybody tell me the difference between PrintStream and PrintWriter ? I know that the first one operates on 8 bits streams whereas the second one on 16 bits streams. Why could the first one not handle Unicodes properly ? Could anybody give some explanation on that ? The main purpose for PrintStream is to provide ability to "print representations ...

29. PrintStream+xls

The Excel .xls format is a proprietary binary format. The file you produced has the right extension, but the wrong format. I recommend you use a simple text format such as tab delimited, if Matlab supports that. If you must write true Excel files, you'll need to use one of the libraries that support this, like POI

30. PrintStream help

It's weird because customers is an instance kind of data, and you're apparently making it static. It's weird to have a constructor initialize static data. It's a little unusual to have a constructor modify static state that isn't about instances, but not weird. But it's definitely weird for a constructor to initialize static data.