java.io
Class PrintStream

java.lang.Object
  extended byjava.io.OutputStream
      extended byjava.io.FilterOutputStream
          extended byjava.io.PrintStream
Direct Known Subclasses:
LogStream

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 be created so as to flush automatically; this means that the flush method is automatically invoked after a byte array is written, one of the println methods is invoked, or a newline character or byte ('\n') is written.

All characters printed by a PrintStream are converted into bytes using the platform's default character encoding. The PrintWriter class should be used in situations that require writing characters rather than bytes.

Since:
JDK1.0
Author:
Frank Yellin, Mark Reinhold

Field Summary
private  boolean autoFlush
           
private  OutputStreamWriter charOut
           
private  boolean closing
           
private  BufferedWriter textOut
          Track both the text- and character-output streams, so that their buffers can be flushed without flushing the entire stream.
private  boolean trouble
           
 
Fields inherited from class java.io.FilterOutputStream
out
 
Constructor Summary
private PrintStream(boolean autoFlush, OutputStream out)
           
  PrintStream(OutputStream out)
          Create a new print stream.
  PrintStream(OutputStream out, boolean autoFlush)
          Create a new print stream.
  PrintStream(OutputStream out, boolean autoFlush, String encoding)
          Create a new print stream.
 
Method Summary
 boolean checkError()
          Flush the stream and check its error state.
 void close()
          Close the stream.
private  void ensureOpen()
          Check to make sure that the stream has not been closed
 void flush()
          Flush the stream.
private  void init(OutputStreamWriter osw)
           
private  void newLine()
           
 void print(boolean b)
          Print a boolean value.
 void print(char c)
          Print a character.
 void print(char[] s)
          Print an array of characters.
 void print(double d)
          Print a double-precision floating-point number.
 void print(float f)
          Print a floating-point number.
 void print(int i)
          Print an integer.
 void print(long l)
          Print a long integer.
 void print(Object obj)
          Print an object.
 void print(String s)
          Print a string.
 void println()
          Terminate the current line by writing the line separator string.
 void println(boolean x)
          Print a boolean and then terminate the line.
 void println(char x)
          Print a character and then terminate the line.
 void println(char[] x)
          Print an array of characters and then terminate the line.
 void println(double x)
          Print a double and then terminate the line.
 void println(float x)
          Print a float and then terminate the line.
 void println(int x)
          Print an integer and then terminate the line.
 void println(long x)
          Print a long and then terminate the line.
 void println(Object x)
          Print an Object and then terminate the line.
 void println(String x)
          Print a String and then terminate the line.
protected  void setError()
          Set the error state of the stream to true.
 void write(byte[] buf, int off, int len)
          Write len bytes from the specified byte array starting at offset off to this stream.
private  void write(char[] buf)
           
 void write(int b)
          Write the specified byte to this stream.
private  void write(String s)
           
 
Methods inherited from class java.io.FilterOutputStream
write
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

autoFlush

private boolean autoFlush

trouble

private boolean trouble

textOut

private BufferedWriter textOut
Track both the text- and character-output streams, so that their buffers can be flushed without flushing the entire stream.


charOut

private OutputStreamWriter charOut

closing

private boolean closing
Constructor Detail

PrintStream

public PrintStream(OutputStream out)
Create a new print stream. This stream will not flush automatically.

Parameters:
out - The output stream to which values and objects will be printed
See Also:
PrintWriter.PrintWriter(java.io.OutputStream)

PrintStream

private PrintStream(boolean autoFlush,
                    OutputStream out)

PrintStream

public PrintStream(OutputStream out,
                   boolean autoFlush)
Create a new print stream.

Parameters:
out - The output stream to which values and objects will be printed
autoFlush - A boolean; if true, the output buffer will be flushed whenever a byte array is written, one of the println methods is invoked, or a newline character or byte ('\n') is written
See Also:
PrintWriter.PrintWriter(java.io.OutputStream, boolean)

PrintStream

public PrintStream(OutputStream out,
                   boolean autoFlush,
                   String encoding)
            throws UnsupportedEncodingException
Create a new print stream.

Parameters:
out - The output stream to which values and objects will be printed
autoFlush - A boolean; if true, the output buffer will be flushed whenever a byte array is written, one of the println methods is invoked, or a newline character or byte ('\n') is written
encoding - The name of a supported character encoding
Throws:
UnsupportedEncodingException - If the named encoding is not supported
Method Detail

init

private void init(OutputStreamWriter osw)

ensureOpen

private void ensureOpen()
                 throws IOException
Check to make sure that the stream has not been closed

Throws:
IOException

flush

public void flush()
Flush the stream. This is done by writing any buffered output bytes to the underlying output stream and then flushing that stream.

Overrides:
flush in class FilterOutputStream
See Also:
OutputStream.flush()

close

public void close()
Close the stream. This is done by flushing the stream and then closing the underlying output stream.

Overrides:
close in class FilterOutputStream
See Also:
OutputStream.close()

checkError

public boolean checkError()
Flush the stream and check its error state. The internal error state is set to true when the underlying output stream throws an IOException other than InterruptedIOException, and when the setError method is invoked. If an operation on the underlying output stream throws an InterruptedIOException, then the PrintStream converts the exception back into an interrupt by doing:
     Thread.currentThread().interrupt();
 
or the equivalent.

Returns:
True if and only if this stream has encountered an IOException other than InterruptedIOException, or the setError method has been invoked

setError

protected void setError()
Set the error state of the stream to true.

Since:
JDK1.1

write

public void write(int b)
Write the specified byte to this stream. If the byte is a newline and automatic flushing is enabled then the flush method will be invoked.

Note that the byte is written as given; to write a character that will be translated according to the platform's default character encoding, use the print(char) or println(char) methods.

Overrides:
write in class FilterOutputStream
Parameters:
b - The byte to be written
See Also:
print(char), println(char)

write

public void write(byte[] buf,
                  int off,
                  int len)
Write len bytes from the specified byte array starting at offset off to this stream. If automatic flushing is enabled then the flush method will be invoked.

Note that the bytes will be written as given; to write characters that will be translated according to the platform's default character encoding, use the print(char) or println(char) methods.

Overrides:
write in class FilterOutputStream
Parameters:
buf - A byte array
off - Offset from which to start taking bytes
len - Number of bytes to write
See Also:
FilterOutputStream.write(int)

write

private void write(char[] buf)

write

private void write(String s)

newLine

private void newLine()

print

public void print(boolean b)
Print a boolean value. The string produced by String.valueOf(boolean) is translated into bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of the write(int) method.

Parameters:
b - The boolean to be printed

print

public void print(char c)
Print a character. The character is translated into one or more bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of the write(int) method.

Parameters:
c - The char to be printed

print

public void print(int i)
Print an integer. The string produced by String.valueOf(int) is translated into bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of the write(int) method.

Parameters:
i - The int to be printed
See Also:
Integer.toString(int)

print

public void print(long l)
Print a long integer. The string produced by String.valueOf(long) is translated into bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of the write(int) method.

Parameters:
l - The long to be printed
See Also:
Long.toString(long)

print

public void print(float f)
Print a floating-point number. The string produced by String.valueOf(float) is translated into bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of the write(int) method.

Parameters:
f - The float to be printed
See Also:
Float.toString(float)

print

public void print(double d)
Print a double-precision floating-point number. The string produced by String.valueOf(double) is translated into bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of the write(int) method.

Parameters:
d - The double to be printed
See Also:
Double.toString(double)

print

public void print(char[] s)
Print an array of characters. The characters are converted into bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of the write(int) method.

Parameters:
s - The array of chars to be printed
Throws:
NullPointerException - If s is null

print

public void print(String s)
Print a string. If the argument is null then the string "null" is printed. Otherwise, the string's characters are converted into bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of the write(int) method.

Parameters:
s - The String to be printed

print

public void print(Object obj)
Print an object. The string produced by the String.valueOf(Object) method is translated into bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of the write(int) method.

Parameters:
obj - The Object to be printed
See Also:
Object.toString()

println

public void println()
Terminate the current line by writing the line separator string. The line separator string is defined by the system property line.separator, and is not necessarily a single newline character ('\n').


println

public void println(boolean x)
Print a boolean and then terminate the line. This method behaves as though it invokes print(boolean) and then println().

Parameters:
x - The boolean to be printed

println

public void println(char x)
Print a character and then terminate the line. This method behaves as though it invokes print(char) and then println().

Parameters:
x - The char to be printed.

println

public void println(int x)
Print an integer and then terminate the line. This method behaves as though it invokes print(int) and then println().

Parameters:
x - The int to be printed.

println

public void println(long x)
Print a long and then terminate the line. This method behaves as though it invokes print(long) and then println().

Parameters:
x - a The long to be printed.

println

public void println(float x)
Print a float and then terminate the line. This method behaves as though it invokes print(float) and then println().

Parameters:
x - The float to be printed.

println

public void println(double x)
Print a double and then terminate the line. This method behaves as though it invokes print(double) and then println().

Parameters:
x - The double to be printed.

println

public void println(char[] x)
Print an array of characters and then terminate the line. This method behaves as though it invokes print(char[]) and then println().

Parameters:
x - an array of chars to print.

println

public void println(String x)
Print a String and then terminate the line. This method behaves as though it invokes print(String) and then println().

Parameters:
x - The String to be printed.

println

public void println(Object x)
Print an Object and then terminate the line. This method behaves as though it invokes print(Object) and then println().

Parameters:
x - The Object to be printed.