PrintWriter

public class PrintWriter extends Writer

Prints formatted representations of objects to a text-output stream. This class implements all of the print methods found in PrintStream. It does not contain methods for writing raw bytes, for which a program should use unencoded byte streams.

Unlike the PrintStream class, if automatic flushing is enabled it will be done only when one of the println, printf, or format methods is invoked, rather than whenever a newline character happens to be output. These methods use the platform's own notion of line separator rather than the newline character.

Methods in this class never throw I/O exceptions, although some of its constructors may. The client may inquire as to whether any errors have occurred by invoking checkError().

Field Summary

protected Writer

out

The underlying character-output stream of this PrintWriter.

Inherited Field Summary

From class java.io.Writer

protected Object

lock

The object used to synchronize operations on this stream.

Public Constructor Summary

	PrintWriter(Writer out) Creates a new PrintWriter, without automatic line flushing.
	PrintWriter(Writer out, boolean autoFlush) Creates a new PrintWriter.
	PrintWriter(OutputStream out) Creates a new PrintWriter, without automatic line flushing, from an existing OutputStream.
	PrintWriter(OutputStream out, boolean autoFlush) Creates a new PrintWriter from an existing OutputStream.
	PrintWriter(String fileName) Creates a new PrintWriter, without automatic line flushing, with the specified file name.
	PrintWriter(String fileName, String csn) Creates a new PrintWriter, without automatic line flushing, with the specified file name and charset.
	PrintWriter(File file) Creates a new PrintWriter, without automatic line flushing, with the specified file.
	PrintWriter(File file, String csn) Creates a new PrintWriter, without automatic line flushing, with the specified file and charset.

Public Method Summary

PrintWriter	append(char c) Appends the specified character to this writer.
PrintWriter	append(CharSequence csq, int start, int end) Appends a subsequence of the specified character sequence to this writer.
PrintWriter	append(CharSequence csq) Appends the specified character sequence to this writer.
boolean	checkError() Flushes the stream if it's not closed and checks its error state.
void	close() Closes the stream and releases any system resources associated with it.
void	flush() Flushes the stream.
PrintWriter	format(Locale l, String format, Object... args) Writes a formatted string to this writer using the specified format string and arguments.
PrintWriter	format(String format, Object... args) Writes a formatted string to this writer using the specified format string and arguments.
void	print(int i) Prints an integer.
void	print(double d) Prints a double-precision floating-point number.
void	print(boolean b) Prints a boolean value.
void	print(char c) Prints a character.
void	print(long l) Prints a long integer.
void	print(float f) Prints a floating-point number.
void	print(String s) Prints a string.
void	print(Object obj) Prints an object.
void	print(char[] s) Prints an array of characters.
PrintWriter	printf(String format, Object... args) A convenience method to write a formatted string to this writer using the specified format string and arguments.
PrintWriter	printf(Locale l, String format, Object... args) A convenience method to write a formatted string to this writer using the specified format string and arguments.
void	println(Object x) Prints an Object and then terminates the line.
void	println(char x) Prints a character and then terminates the line.
void	println(boolean x) Prints a boolean value and then terminates the line.
void	println(long x) Prints a long integer and then terminates the line.
void	println() Terminates the current line by writing the line separator string.
void	println(int x) Prints an integer and then terminates the line.
void	println(String x) Prints a String and then terminates the line.
void	println(char[] x) Prints an array of characters and then terminates the line.
void	println(float x) Prints a floating-point number and then terminates the line.
void	println(double x) Prints a double-precision floating-point number and then terminates the line.
void	write(int c) Writes a single character.
void	write(char[] buf, int off, int len) Writes A Portion of an array of characters.
void	write(String s) Writes a string.
void	write(String s, int off, int len) Writes a portion of a string.
void	write(char[] buf) Writes an array of characters.

Protected Method Summary

void	clearError() Clears the error state of this stream.
void	setError() Indicates that an error has occurred.

Inherited Method Summary

From class java.io.Writer

Writer	append(char c) Appends the specified character to this writer.
Writer	append(CharSequence csq, int start, int end) Appends a subsequence of the specified character sequence to this writer.
Writer	append(CharSequence csq) Appends the specified character sequence to this writer.
abstract void	close() Closes the stream, flushing it first.
abstract void	flush() Flushes the stream.
void	write(String str) Writes a string.
void	write(int c) Writes a single character.
void	write(String str, int off, int len) Writes a portion of a string.
abstract void	write(char[] cbuf, int off, int len) Writes a portion of an array of characters.
void	write(char[] cbuf) Writes an array of characters.

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

From interface java.lang.Appendable

abstract Appendable	append(char c) Appends the specified character to this Appendable.
abstract Appendable	append(CharSequence csq, int start, int end) Appends a subsequence of the specified character sequence to this Appendable.
abstract Appendable	append(CharSequence csq) Appends the specified character sequence to this Appendable.

From interface java.io.Closeable

abstract void

close() Closes this stream and releases any system resources associated with it.

From interface java.io.Flushable

abstract void

flush() Flushes this stream by writing any buffered output to the underlying stream.

From interface java.lang.AutoCloseable

abstract void

close() Closes this resource, relinquishing any underlying resources.

Fields

protected Writer out

The underlying character-output stream of this PrintWriter.

Public Constructors

public PrintWriter (Writer out)

Creates a new PrintWriter, without automatic line flushing.

Parameters

out	A character-output stream

public PrintWriter (Writer out, boolean autoFlush)

Creates a new PrintWriter.

Parameters

out	A character-output stream
autoFlush	A boolean; if true, the println, printf, or format methods will flush the output buffer

public PrintWriter (OutputStream out)

Creates a new PrintWriter, without automatic line flushing, from an existing OutputStream. This convenience constructor creates the necessary intermediate OutputStreamWriter, which will convert characters into bytes using the default character encoding.

Parameters

out	An output stream

See Also

• OutputStreamWriter.OutputStreamWriter(java.io.OutputStream)

public PrintWriter (OutputStream out, boolean autoFlush)

Creates a new PrintWriter from an existing OutputStream. This convenience constructor creates the necessary intermediate OutputStreamWriter, which will convert characters into bytes using the default character encoding.

Parameters

out	An output stream
autoFlush	A boolean; if true, the println, printf, or format methods will flush the output buffer

See Also

• OutputStreamWriter.OutputStreamWriter(java.io.OutputStream)

public PrintWriter (String fileName)

Creates a new PrintWriter, without automatic line flushing, with the specified file name. This convenience constructor creates the necessary intermediate OutputStreamWriter, which will encode characters using the {@linkplain java.nio.charset.Charset#defaultCharset() default charset} for this instance of the Java virtual machine.

Parameters

fileName	The name of the file to use as the destination of this writer. If the file exists then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.

Throws

FileNotFoundException	If the given string does not denote an existing, writable regular file and a new regular file of that name cannot be created, or if some other error occurs while opening or creating the file
SecurityException	If a security manager is present and checkWrite(fileName) denies write access to the file

public PrintWriter (String fileName, String csn)

Creates a new PrintWriter, without automatic line flushing, with the specified file name and charset. This convenience constructor creates the necessary intermediate OutputStreamWriter, which will encode characters using the provided charset.

Parameters

fileName	The name of the file to use as the destination of this writer. If the file exists then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.
csn	The name of a supported {@linkplain java.nio.charset.Charset charset}

Throws

FileNotFoundException	If the given string does not denote an existing, writable regular file and a new regular file of that name cannot be created, or if some other error occurs while opening or creating the file
SecurityException	If a security manager is present and checkWrite(fileName) denies write access to the file
UnsupportedEncodingException	If the named charset is not supported

public PrintWriter (File file)

Creates a new PrintWriter, without automatic line flushing, with the specified file. This convenience constructor creates the necessary intermediate OutputStreamWriter, which will encode characters using the {@linkplain java.nio.charset.Charset#defaultCharset() default charset} for this instance of the Java virtual machine.

Parameters

file	The file to use as the destination of this writer. If the file exists then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.

Throws

FileNotFoundException	If the given file object does not denote an existing, writable regular file and a new regular file of that name cannot be created, or if some other error occurs while opening or creating the file
SecurityException	If a security manager is present and checkWrite(file.getPath()) denies write access to the file

public PrintWriter (File file, String csn)

Creates a new PrintWriter, without automatic line flushing, with the specified file and charset. This convenience constructor creates the necessary intermediate OutputStreamWriter, which will encode characters using the provided charset.

Parameters

file	The file to use as the destination of this writer. If the file exists then it will be truncated to zero size; otherwise, a new file will be created. The output will be written to the file and is buffered.
csn	The name of a supported {@linkplain java.nio.charset.Charset charset}

Throws

FileNotFoundException	If the given file object does not denote an existing, writable regular file and a new regular file of that name cannot be created, or if some other error occurs while opening or creating the file
SecurityException	If a security manager is present and checkWrite(file.getPath()) denies write access to the file
UnsupportedEncodingException	If the named charset is not supported

Public Methods

public PrintWriter append (char c)

Appends the specified character to this writer.

An invocation of this method of the form out.append(c) behaves in exactly the same way as the invocation

     out.write(c) 

Parameters

c	The 16-bit character to append

Returns

• This writer

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

Appends a subsequence of the specified character sequence to this writer.

An invocation of this method of the form out.append(csq, start, end) when csq is not null, behaves in exactly the same way as the invocation

     out.write(csq.subSequence(start, end).toString()) 

Parameters

csq	The character sequence from which a subsequence will be appended. If csq is null, then characters will be appended as if csq contained the four characters "null".
start	The index of the first character in the subsequence
end	The index of the character following the last character in the subsequence

Returns

• This writer

Throws

IndexOutOfBoundsException	If start or end are negative, start is greater than end, or end is greater than csq.length()

public PrintWriter append (CharSequence csq)

Appends the specified character sequence to this writer.

An invocation of this method of the form out.append(csq) behaves in exactly the same way as the invocation

     out.write(csq.toString()) 

Depending on the specification of toString for the character sequence csq, the entire sequence may not be appended. For instance, invoking the toString method of a character buffer will return a subsequence whose content depends upon the buffer's position and limit.

Parameters

csq	The character sequence to append. If csq is null, then the four characters "null" are appended to this writer.

Returns

• This writer

public boolean checkError ()

Flushes the stream if it's not closed and checks its error state.

Returns

• true if the print stream has encountered an error, either on the underlying output stream or during a format conversion.

public void close ()

Closes the stream and releases any system resources associated with it. Closing a previously closed stream has no effect.

See Also

• checkError()

public void flush ()

Flushes the stream.

See Also

• checkError()

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

Writes a formatted string to this writer using the specified format string and arguments. If automatic flushing is enabled, calls to this method will flush the output buffer.

Parameters

l	The {@linkplain java.util.Locale locale} to apply during formatting. If l is null then no localization is applied.
format	A format string as described in Format string syntax.
args	Arguments referenced by the format specifiers in the format string. If there are more arguments than format specifiers, the extra arguments are ignored. The number of arguments is variable and may be zero. The maximum number of arguments is limited by the maximum dimension of a Java array as defined by The Java™ Virtual Machine Specification. The behaviour on a null argument depends on the conversion.

Returns

• This writer

Throws

IllegalFormatException	If a format string contains an illegal syntax, a format specifier that is incompatible with the given arguments, insufficient arguments given the format string, or other illegal conditions. For specification of all possible formatting errors, see the Details section of the formatter class specification.
NullPointerException	If the format is null

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

Writes a formatted string to this writer using the specified format string and arguments. If automatic flushing is enabled, calls to this method will flush the output buffer.

The locale always used is the one returned by Locale.getDefault(), regardless of any previous invocations of other formatting methods on this object.

Parameters

format

A format string as described in Format string syntax.

args

Arguments referenced by the format specifiers in the format string. If there are more arguments than format specifiers, the extra arguments are ignored. The number of arguments is variable and may be zero. The maximum number of arguments is limited by the maximum dimension of a Java array as defined by The Java™ Virtual Machine Specification. The behaviour on a null argument depends on the conversion.

Returns

• This writer

Throws

IllegalFormatException	If a format string contains an illegal syntax, a format specifier that is incompatible with the given arguments, insufficient arguments given the format string, or other illegal conditions. For specification of all possible formatting errors, see the Details section of the Formatter class specification.
NullPointerException	If the format is null

public void print (int i)

Prints 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)

public void print (double d)

Prints 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)

public void print (boolean b)

Prints 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

public void print (char c)

Prints 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

public void print (long l)

Prints 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)

public void print (float f)

Prints 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)

public void print (String s)

Prints 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

public void print (Object obj)

Prints 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()

public void print (char[] s)

Prints 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

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

A convenience method to write a formatted string to this writer using the specified format string and arguments. If automatic flushing is enabled, calls to this method will flush the output buffer.

An invocation of this method of the form out.printf(format, args) behaves in exactly the same way as the invocation

     out.format(format, args) 

Parameters

format

A format string as described in Format string syntax.

args

Arguments referenced by the format specifiers in the format string. If there are more arguments than format specifiers, the extra arguments are ignored. The number of arguments is variable and may be zero. The maximum number of arguments is limited by the maximum dimension of a Java array as defined by The Java™ Virtual Machine Specification. The behaviour on a null argument depends on the conversion.

Returns

• This writer

Throws

IllegalFormatException	If a format string contains an illegal syntax, a format specifier that is incompatible with the given arguments, insufficient arguments given the format string, or other illegal conditions. For specification of all possible formatting errors, see the Details section of the formatter class specification.
NullPointerException	If the format is null

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

A convenience method to write a formatted string to this writer using the specified format string and arguments. If automatic flushing is enabled, calls to this method will flush the output buffer.

An invocation of this method of the form out.printf(l, format, args) behaves in exactly the same way as the invocation

     out.format(l, format, args) 

Parameters

l	The {@linkplain java.util.Locale locale} to apply during formatting. If l is null then no localization is applied.
format	A format string as described in Format string syntax.
args	Arguments referenced by the format specifiers in the format string. If there are more arguments than format specifiers, the extra arguments are ignored. The number of arguments is variable and may be zero. The maximum number of arguments is limited by the maximum dimension of a Java array as defined by The Java™ Virtual Machine Specification. The behaviour on a null argument depends on the conversion.

Returns

• This writer

Throws

IllegalFormatException	If a format string contains an illegal syntax, a format specifier that is incompatible with the given arguments, insufficient arguments given the format string, or other illegal conditions. For specification of all possible formatting errors, see the Details section of the formatter class specification.
NullPointerException	If the format is null

public void println (Object x)

Prints an Object and then terminates the line. This method calls at first String.valueOf(x) to get the printed object's string value, then behaves as though it invokes print(String) and then println().

Parameters

x	The Object to be printed.

public void println (char x)

Prints a character and then terminates the line. This method behaves as though it invokes print(char) and then println().

Parameters

x	the char value to be printed

public void println (boolean x)

Prints a boolean value and then terminates the line. This method behaves as though it invokes print(boolean) and then println().

Parameters

x	the boolean value to be printed

public void println (long x)

Prints a long integer and then terminates the line. This method behaves as though it invokes print(long) and then println().

Parameters

x	the long value to be printed

public void println ()

Terminates 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').

public void println (int x)

Prints an integer and then terminates the line. This method behaves as though it invokes print(int) and then println().

Parameters

x	the int value to be printed

public void println (String x)

Prints a String and then terminates the line. This method behaves as though it invokes print(String) and then println().

Parameters

x	the String value to be printed

public void println (char[] x)

Prints an array of characters and then terminates the line. This method behaves as though it invokes print(char[]) and then println().

Parameters

x	the array of char values to be printed

public void println (float x)

Prints a floating-point number and then terminates the line. This method behaves as though it invokes print(float) and then println().

Parameters

x	the float value to be printed

public void println (double x)

Prints a double-precision floating-point number and then terminates the line. This method behaves as though it invokes print(double) and then println().

Parameters

x	the double value to be printed

public void write (int c)

Writes a single character.

Parameters

c	int specifying a character to be written.

public void write (char[] buf, int off, int len)

Writes A Portion of an array of characters.

Parameters

buf	Array of characters
off	Offset from which to start writing characters
len	Number of characters to write

public void write (String s)

Writes a string. This method cannot be inherited from the Writer class because it must suppress I/O exceptions.

Parameters

s	String to be written

public void write (String s, int off, int len)

Writes a portion of a string.

Parameters

s	A String
off	Offset from which to start writing characters
len	Number of characters to write

public void write (char[] buf)

Writes an array of characters. This method cannot be inherited from the Writer class because it must suppress I/O exceptions.

Parameters

buf	Array of characters to be written

Protected Methods

protected void clearError ()

Clears the error state of this stream.

This method will cause subsequent invocations of checkError() to return false until another write operation fails and invokes setError().

protected void setError ()

Indicates that an error has occurred.

This method will cause subsequent invocations of checkError() to return true until clearError() is invoked.