java.io

Class PrintWriter

java.lang.Object

java.io.Writer

java.io.PrintWriter

All Implemented Interfaces:

Closeable, Flushable, Appendable

public class PrintWriter
extends Writer

This class prints Java primitive values and objects to a stream as text. None of the methods in this class throw an exception. However, errors can be detected by calling the checkError() method. Additionally, this stream can be designated as "autoflush" when created so that any writes are automatically flushed to the underlying output sink whenever one of the println methods is called. (Note that this differs from the PrintStream class which also auto-flushes when it encounters a newline character in the chars written).

Author:

Per Bothner (bothner@cygnus.com), Aaron M. Renn (arenn@urbanophile.com)

Constructor Summary

Constructors

Constructor and Description
PrintWriter(File file) This initializes a new PrintWriter object to write to the specified file.
PrintWriter(File file, String enc) This initializes a new PrintWriter object to write to the specified file.
PrintWriter(OutputStream out) This method initializes a new PrintWriter object to write to the specified OutputStream.
PrintWriter(OutputStream out, boolean autoflush) This method initializes a new PrintWriter object to write to the specified OutputStream.
PrintWriter(String file) This initializes a new PrintWriter object to write to the specified file.
PrintWriter(String file, String enc) This initializes a new PrintWriter object to write to the specified file.
PrintWriter(Writer wr) This method intializes a new PrintWriter object to write to the specified output sink.
PrintWriter(Writer wr, boolean autoflush) This method intializes a new PrintWriter object to write to the specified output sink.

Method Summary

Modifier and Type	Method and Description
PrintWriter	append(char c) Appends the Unicode character, c, to this Appendable object.
PrintWriter	append(CharSequence cs) Appends the specified sequence of Unicode characters to this Appendable object.
PrintWriter	append(CharSequence cs, int start, int end) Appends the specified subsequence of Unicode characters to this Appendable object, starting and ending at the specified positions within the sequence.
boolean	checkError() This method checks to see if an error has occurred on this stream.
void	close() This method closes this stream and all underlying streams.
void	flush() This method flushes any buffered chars to the underlying stream and then flushes that stream as well.
PrintWriter	format(String format, Object... args)
void	print(boolean bool) This methods prints a boolean value to the stream.
void	print(char ch) This method prints a char to the stream.
void	print(char[] charArray) This method prints an array of characters to the stream.
void	print(double dnum) This method prints a double to the stream.
void	print(float fnum) This method prints a float to the stream.
void	print(int inum) This method prints an integer to the stream.
void	print(long lnum) This method prints a long to the stream.
void	print(Object obj) This method prints an Object to the stream.
void	print(String str) This method prints a String to the stream.
PrintWriter	printf(String format, Object... args)
void	println() This method prints a line separator sequence to the stream.
void	println(boolean bool) This methods prints a boolean value to the stream.
void	println(char ch) This method prints a char to the stream.
void	println(char[] charArray) This method prints an array of characters to the stream.
void	println(double dnum) This method prints a double to the stream.
void	println(float fnum) This method prints a float to the stream.
void	println(int inum) This method prints an integer to the stream.
void	println(long lnum) This method prints a long to the stream.
void	println(Object obj) This method prints an Object to the stream.
void	println(String str) This method prints a String to the stream.
void	write(char[] charArray) This method write all the chars in the specified array to the output.
void	write(char[] charArray, int offset, int count) This method writes count chars from the specified array starting at index offset into the array.
void	write(int ch) This method writes a single char to the stream.
void	write(String str) This method writes the contents of the specified String to the underlying stream.
void	write(String str, int offset, int count) This method writes count chars from the specified String to the output starting at character position offset into the String

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PrintWriter

public PrintWriter(File file)
            throws IOException

This initializes a new PrintWriter object to write to the specified file. It creates a FileOutputStream object and wraps it in an OutputStreamWriter using the default encoding.

Parameters:

file - the file to write to

Throws:

IOException

Since:

1.5

PrintWriter

public PrintWriter(File file,
                   String enc)
            throws IOException

This initializes a new PrintWriter object to write to the specified file. It creates a FileOutputStream object and wraps it in an OutputStreamWriter using the specified encoding.

Parameters:

file - the file to write to

enc - the encoding to use

Throws:

IOException

Since:

1.5

PrintWriter

public PrintWriter(OutputStream out)

This method initializes a new PrintWriter object to write to the specified OutputStream. Characters will be converted to chars using the system default encoding. Auto-flush functionality will not be enabled.

Parameters:

out - The OutputStream to write to

PrintWriter

public PrintWriter(OutputStream out,
                   boolean autoflush)

This method initializes a new PrintWriter object to write to the specified OutputStream. Characters will be converted to chars using the system default encoding. This form of the constructor allows auto-flush functionality to be enabled if desired

Parameters:

out - The OutputStream to write to

autoflush - true to flush the stream after every println call, false otherwise.

PrintWriter

public PrintWriter(String file)
            throws IOException

This initializes a new PrintWriter object to write to the specified file. It creates a FileOutputStream object and wraps it in an OutputStreamWriter using the default encoding.

Parameters:

file - name of the file to write to

Throws:

IOException

Since:

1.5

PrintWriter

public PrintWriter(String file,
                   String enc)
            throws IOException

This initializes a new PrintWriter object to write to the specified file. It creates a FileOutputStream object and wraps it in an OutputStreamWriter using the specified encoding.

Parameters:

file - name of the file to write to

enc - the encoding to use

Throws:

IOException

Since:

1.5

PrintWriter

public PrintWriter(Writer wr)

This method intializes a new PrintWriter object to write to the specified output sink. The form of the constructor does not enable auto-flush functionality.

Parameters:

wr - The Writer to write to.

PrintWriter

public PrintWriter(Writer wr,
                   boolean autoflush)

This method intializes a new PrintWriter object to write to the specified output sink. This constructor also allows "auto-flush" functionality to be specified where the stream will be flushed after every line is terminated or newline character is written.

Parameters:

wr - The Writer to write to.

autoflush - true to flush the stream after every line, false otherwise

Method Detail

append

public PrintWriter append(char c)

Description copied from interface: Appendable

Appends the Unicode character, c, to this Appendable object.

Specified by:

append in interface Appendable

Overrides:

append in class Writer

Parameters:

c - the character to append.

Returns:

a reference to this object.

Since:

1.5

append

public PrintWriter append(CharSequence cs)

Description copied from interface: Appendable

Appends the specified sequence of Unicode characters to this Appendable object. The entire sequence may not be appended, if constrained by the underlying implementation. For example, a buffer may reach its size limit before the entire sequence is appended.

Specified by:

append in interface Appendable

Overrides:

append in class Writer

Parameters:

cs - the character sequence to append. If seq is null, then the string "null" (the string representation of null) is appended.

Returns:

a reference to this object.

Since:

1.5

append

public PrintWriter append(CharSequence cs,
                          int start,
                          int end)

Description copied from interface: Appendable

Appends the specified subsequence of Unicode characters to this Appendable object, starting and ending at the specified positions within the sequence. The entire sequence may not be appended, if constrained by the underlying implementation. For example, a buffer may reach its size limit before the entire sequence is appended. The behaviour of this method matches the behaviour of append(seq.subSequence(start,end)) when the sequence is not null.

Specified by:

append in interface Appendable

Overrides:

append in class Writer

Parameters:

cs - the character sequence to append. If seq is null, then the string "null" (the string representation of null) is appended.

start - the index of the first Unicode character to use from the sequence.

end - the index of the last Unicode character to use from the sequence.

Returns:

a reference to this object.

Since:

1.5

checkError

public boolean checkError()

This method checks to see if an error has occurred on this stream. Note that once an error has occurred, this method will continue to report true forever for this stream. Before checking for an error condition, this method flushes the stream.

Returns:

true if an error has occurred, false otherwise

close

public void close()

This method closes this stream and all underlying streams.

Specified by:

close in interface Closeable

Specified by:

close in class Writer

flush

public void flush()

This method flushes any buffered chars to the underlying stream and then flushes that stream as well.

Specified by:

flush in interface Flushable

Specified by:

flush in class Writer

format

public PrintWriter format(String format,
                          Object... args)

Since:

1.5

print

public void print(boolean bool)

This methods prints a boolean value to the stream. true values are printed as "true" and false values are printed as "false".

Parameters:

bool - The boolean value to print

print

public void print(char ch)

This method prints a char to the stream. The actual value printed is determined by the character encoding in use.

Parameters:

ch - The char value to be printed

print

public void print(char[] charArray)

This method prints an array of characters to the stream. The actual value printed depends on the system default encoding.

Parameters:

charArray - The array of characters to print.

print

public void print(double dnum)

This method prints a double to the stream. The value printed is determined using the String.valueOf() method.

Parameters:

dnum - The double value to be printed

print

public void print(float fnum)

This method prints a float to the stream. The value printed is determined using the String.valueOf() method.

Parameters:

fnum - The float value to be printed

print

public void print(int inum)

This method prints an integer to the stream. The value printed is determined using the String.valueOf() method.

Parameters:

inum - The int value to be printed

print

public void print(long lnum)

This method prints a long to the stream. The value printed is determined using the String.valueOf() method.

Parameters:

lnum - The long value to be printed

print

public void print(Object obj)

This method prints an Object to the stream. The actual value printed is determined by calling the String.valueOf() method.

Parameters:

obj - The Object to print.

print

public void print(String str)

This method prints a String to the stream. The actual value printed depends on the system default encoding.

Parameters:

str - The String to print.

printf

public PrintWriter printf(String format,
                          Object... args)

Since:

1.5

println

public void println()

This method prints a line separator sequence to the stream. The value printed is determined by the system property line.separator and is not necessarily the Unix '\n' newline character.

println

public void println(boolean bool)

This methods prints a boolean value to the stream. true values are printed as "true" and false values are printed as "false". This method prints a line termination sequence after printing the value.

Parameters:

bool - The boolean value to print

println

public void println(char ch)

This method prints a char to the stream. The actual value printed is determined by the character encoding in use. This method prints a line termination sequence after printing the value.

Parameters:

ch - The char value to be printed

println

public void println(char[] charArray)

This method prints an array of characters to the stream. The actual value printed depends on the system default encoding. This method prints a line termination sequence after printing the value.

Parameters:

charArray - The array of characters to print.

println

public void println(double dnum)

This method prints a double to the stream. The value printed is determined using the String.valueOf() method. This method prints a line termination sequence after printing the value.

Parameters:

dnum - The double value to be printed

println

public void println(float fnum)

This method prints a float to the stream. The value printed is determined using the String.valueOf() method. This method prints a line termination sequence after printing the value.

Parameters:

fnum - The float value to be printed

println

public void println(int inum)

This method prints an integer to the stream. The value printed is determined using the String.valueOf() method. This method prints a line termination sequence after printing the value.

Parameters:

inum - The int value to be printed

println

public void println(long lnum)

This method prints a long to the stream. The value printed is determined using the String.valueOf() method. This method prints a line termination sequence after printing the value.

Parameters:

lnum - The long value to be printed

println

public void println(Object obj)

This method prints an Object to the stream. The actual value printed is determined by calling the String.valueOf() method. This method prints a line termination sequence after printing the value.

Parameters:

obj - The Object to print.

println

public void println(String str)

This method prints a String to the stream. The actual value printed depends on the system default encoding. This method prints a line termination sequence after printing the value.

Parameters:

str - The String to print.

write

public void write(char[] charArray)

This method write all the chars in the specified array to the output.

Overrides:

write in class Writer

Parameters:

charArray - The array of characters to write

write

public void write(char[] charArray,
                  int offset,
                  int count)

This method writes count chars from the specified array starting at index offset into the array.

Specified by:

write in class Writer

Parameters:

charArray - The array of chars to write

offset - The index into the array to start writing from

count - The number of chars to write

write

public void write(int ch)

This method writes a single char to the stream.

Overrides:

write in class Writer

Parameters:

ch - The char to be written, passed as a int

write

public void write(String str)

This method writes the contents of the specified String to the underlying stream.

Overrides:

write in class Writer

Parameters:

str - The String to write

write

public void write(String str,
                  int offset,
                  int count)

This method writes count chars from the specified String to the output starting at character position offset into the String

Overrides:

write in class Writer

Parameters:

str - The String to write chars from

offset - The offset into the String to start writing from

count - The number of chars to write.