java.io
Class PrintStream

java.lang.Object
  java.io.OutputStream
      java.io.FilterOutputStream
          java.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.