java.io
Class PrintWriter

java.lang.Object
  java.io.Writer
      java.io.PrintWriter

All Implemented Interfaces:

Closeable, Flushable, Appendable

public class PrintWriter
extends Writer

PrintWriter is a class which takes either an OutputStream or Writer and provides convenience methods for printing common data types in a human readable format on the stream. No IOExceptions are thrown by this class. Instead, callers should call checkError() to see if a problem has been encountered in this Writer.

Field Summary

protected Writer

out The writer to output data to.

Fields inherited from class java.io.Writer

lock, TOKEN_NULL

Constructor Summary

PrintWriter(File file)
Constructs a new PrintWriter on the File file.

PrintWriter(File file, String csn)
Constructs a new PrintWriter on the File file.

PrintWriter(OutputStream out)
Constructs a new PrintWriter on the OutputStream out.

PrintWriter(OutputStream out, boolean autoflush)
Constructs a new PrintWriter on the OutputStream out.

PrintWriter(String fileName)
Constructs a new PrintWriter on a file with the given file name fileName.

PrintWriter(String fileName, String csn)
Constructs a new PrintWriter on a file with the given file name fileName.

PrintWriter(Writer wr)
Constructs a new PrintWriter on the Writer wr.

PrintWriter(Writer wr, boolean autoflush)
Constructs a new PrintWriter on the given writer.

Method Summary

PrintWriter	append(char c) Append a char cto the PrintWriter.
PrintWriter	append(CharSequence csq) Append a CharSequence csq to the PrintWriter.
PrintWriter	append(CharSequence csq, int start, int end) Append a subsequence of a CharSequence csq to the PrintWriter.
boolean	checkError() Returns a boolean indicating whether or not this PrintWriter has encountered an error.
void	close() Close this PrintWriter.
void	flush() Flush this PrintWriter to ensure all pending data is sent out to the target Writer.
PrintWriter	format(Locale l, String format, Object... args) Writes a string formatted by an intermediate Formatter to this writer using the given format string and arguments.
PrintWriter	format(String format, Object... args) Writes a string formatted by an intermediate Formatter to this writer using the given format string and arguments.
void	print(boolean bool) Prints the String representation of the boolean parameter bool to the target Writer.
void	print(char ch) Prints the String representation of the character parameter ch to the target Writer.
void	print(char[] charArray) Prints the String representation of the character array parameter charArray to the target Writer.
void	print(double dnum) Prints the String representation of the double parameter dnum to the target Writer.
void	print(float fnum) Prints the String representation of the float parameter fnum to the target Writer.
void	print(int inum) Prints the String representation of the int parameter inum to the target Writer.
void	print(long lnum) Prints the String representation of the long parameter lnum to the target Writer.
void	print(Object obj) Prints the String representation of the Object parameter obj to the target Writer.
void	print(String str) Prints the String representation of the String parameter str to the target Writer.
PrintWriter	printf(Locale l, String format, Object... args) Prints a formatted string.
PrintWriter	printf(String format, Object... args) Prints a formatted string.
void	println() Prints the String representation of the System property "line.separator" to the target Writer.
void	println(boolean bool) Prints the String representation of the boolean parameter bool to the target Writer followed by the System property "line.separator".
void	println(char ch) Prints the String representation of the character parameter ch to the target Writer followed by the System property "line.separator".
void	println(char[] charArray) Prints the String representation of the character array parameter charArray to the target Writer followed by the System property "line.separator".
void	println(double dnum) Prints the String representation of the double parameter dnum to the target Writer followed by the System property "line.separator".
void	println(float fnum) Prints the String representation of the float parameter fnum to the target Writer followed by the System property "line.separator".
void	println(int inum) Prints the String representation of the int parameter inum to the target Writer followed by the System property "line.separator".
void	println(long lnum) Prints the String representation of the long parameter lnum to the target Writer followed by the System property "line.separator".
void	println(Object obj) Prints the String representation of the Object parameter obj to the target Writer followed by the System property "line.separator".
void	println(String str) Prints the String representation of the String parameter str to the target Writer followed by the System property "line.separator".
protected void	setError() Set the flag indicating that this PrintWriter has encountered an IO error.
void	write(char[] buf) Writes the entire character buffer buf to this Writer.
void	write(char[] buf, int offset, int count) Writes count characters starting at offset in buf to this Writer.
void	write(int oneChar) Writes the specified character to this Writer.
void	write(String str) Writes the characters from the String str to this Writer.
void	write(String str, int offset, int count) Writes count characters from the String str starting at offset to this Writer.

Methods inherited from class java.lang.Object

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

Field Detail

out

protected Writer out

The writer to output data to.

Constructor Detail

PrintWriter

public PrintWriter(OutputStream out)

Constructs a new PrintWriter on the OutputStream out. All writes to the target can now take place through this PrintWriter. By default, the PrintWriter is set to not autoflush when println() is called.

Parameters:

out - the the OutputStream to provide convenience methods on.

PrintWriter

public PrintWriter(OutputStream out,
                   boolean autoflush)

Constructs a new PrintWriter on the OutputStream out. All writes to the target can now take place through this PrintWriter. By default, the PrintWriter is set to not autoflush when println() is called.

Parameters:

out - the the OutputStream to provide convenience methods on.

autoflush - whether to flush when println() is called.

PrintWriter

public PrintWriter(Writer wr)

Constructs a new PrintWriter on the Writer wr. All writes to the target can now take place through this PrintWriter. By default, the PrintWriter is set to not autoflush when println() is called.

Parameters:

wr - the Writer to provide convenience methods on.

PrintWriter

public PrintWriter(Writer wr,
                   boolean autoflush)

Constructs a new PrintWriter on the given writer. All writes to the target can now take place through this PrintWriter. By default, the PrintWriter is set to not autoflush when println() is called.

Parameters:

wr - the Writer to provide convenience methods on.

autoflush - whether to flush when println() is called.

PrintWriter

public PrintWriter(File file)
            throws FileNotFoundException

Constructs a new PrintWriter on the File file. The automatic flushing is set to false. An intermediate OutputStreamWriter will use the default for the current JVM instance charset to encode characters.

Parameters:

file - This writer's buffered destination.

Throws:

FileNotFoundException - If there is no such a file or some other error occurs due to the given file opening.

PrintWriter

public PrintWriter(File file,
                   String csn)
            throws FileNotFoundException,
                   UnsupportedEncodingException

Constructs a new PrintWriter on the File file. The automatic flushing is set to false. An intermediate OutputStreamWriter will use a charset with the given name csn to encode characters.

Parameters:

file - This writer's buffered destination.

csn - A charset name.

Throws:

FileNotFoundException - If there is no such a file or some other error occurs due to the given file opening.

UnsupportedEncodingException - If a charset with the given name is not supported.

PrintWriter

public PrintWriter(String fileName)
            throws FileNotFoundException

Constructs a new PrintWriter on a file with the given file name fileName. The automatic flushing is set to false. An intermediate OutputStreamWriter will use the default for the current JVM instance charset to encode characters.

Parameters:

fileName - The name of file which is this writer's buffered destination.

Throws:

FileNotFoundException - If there is no such a file or some other error occurs due to the given file opening.

PrintWriter

public PrintWriter(String fileName,
                   String csn)
            throws FileNotFoundException,
                   UnsupportedEncodingException

Constructs a new PrintWriter on a file with the given file name fileName. The automatic flushing is set to false. An intermediate OutputStreamWriter will use a charset with the given name csn to encode characters.

Parameters:

fileName - The name of file which is this writer's buffered destination.

csn - A charset name.

Throws:

FileNotFoundException - If there is no such a file or some other error occurs due to the given file opening.

UnsupportedEncodingException - If a charset with the given name is not supported.

Method Detail

checkError

public boolean checkError()

Returns a boolean indicating whether or not this PrintWriter has encountered an error. If so, the receiver should probably be closed since further writes will not actually take place. A side effect of calling checkError is that the target Writer is flushed.

Returns:

boolean has an error occurred in this PrintWriter.

close

public void close()

Close this PrintWriter. This implementation flushes and then closes the target writer. If an error occurs, set an error in this PrintWriter to true.

Specified by:

close in interface Closeable

Specified by:

close in class Writer

flush

public void flush()

Flush this PrintWriter to ensure all pending data is sent out to the target Writer. This implementation flushes the target writer. If an error occurs, set an error in this PrintWriter to true.

Specified by:

flush in interface Flushable

Specified by:

flush in class Writer

format

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

Writes a string formatted by an intermediate Formatter to this writer using the given format string and arguments. A call to this method flushes the buffered output, if the automatic flushing is enabled.

The method uses the default for the current JVM instance locale, as if it is specified by the Locale.getDefault() call.

Parameters:

format - A format string.

args - The arguments list. If there are more arguments than those specified by the format string, then the additional arguments are ignored.

Returns:

This writer.

Throws:

IllegalFormatException - If the format string is illegal or incompatible with the arguments or the arguments are less than those required by the format string or any other illegal situation.

NullPointerException - If the given format is null.

format

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

Writes a string formatted by an intermediate Formatter to this writer using the given format string and arguments. A call to this method flushes the buffered output, if the automatic flushing is enabled.

Parameters:

l - The locale used in the method. If locale is null, then no localization will be applied.

format - A format string.

args - The arguments list. If there are more arguments than those specified by the format string, then the additional arguments are ignored.

Returns:

This writer.

Throws:

IllegalFormatException - If the format string is illegal or incompatible with the arguments or the arguments are less than those required by the format string or any other illegal situation.

NullPointerException - If the given format is null.

printf

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

Prints a formatted string. The behavior of this method is the same as this writer's format(String format, Object... args) method.

The method uses the default for the current JVM instance locale, as if it is specified by the Locale.getDefault() call.

Parameters:

format - A format string.

args - The arguments list. If there are more arguments than those specified by the format string, then the additional arguments are ignored.

Returns:

This writer.

Throws:

IllegalFormatException - If the format string is illegal or incompatible with the arguments or the arguments are less than those required by the format string or any other illegal situation.

NullPointerException - If the given format is null.

printf

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

Prints a formatted string. The behavior of this method is the same as this writer's format(Locale l, String format, Object... args) method.

Parameters:

l - The locale used in the method. If locale is null, then no localization will be applied.

format - A format string.

args - The arguments list. If there are more arguments than those specified by the format string, then the additional arguments are ignored.

Returns:

This writer.

Throws:

IllegalFormatException - If the format string is illegal or incompatible with the arguments or the arguments are less than those required by the format string or any other illegal situation.

NullPointerException - If the given format is null.

print

public void print(char[] charArray)

Prints the String representation of the character array parameter charArray to the target Writer.

Parameters:

charArray - the character array to print on this Writer.

print

public void print(char ch)

Prints the String representation of the character parameter ch to the target Writer.

Parameters:

ch - the character to print on this Writer.

print

public void print(double dnum)

Prints the String representation of the double parameter dnum to the target Writer.

Parameters:

dnum - the double to print on this Writer.

print

public void print(float fnum)

Prints the String representation of the float parameter fnum to the target Writer.

Parameters:

fnum - the float to print on this Writer.

print

public void print(int inum)

Prints the String representation of the int parameter inum to the target Writer.

Parameters:

inum - the int to print on this Writer.

print

public void print(long lnum)

Prints the String representation of the long parameter lnum to the target Writer.

Parameters:

lnum - the long to print on this Writer.

print

public void print(Object obj)

Prints the String representation of the Object parameter obj to the target Writer.

Parameters:

obj - the Object to print on this Writer.

print

public void print(String str)

Prints the String representation of the String parameter str to the target Writer.

Parameters:

str - the String to print on this Writer.

print

public void print(boolean bool)

Prints the String representation of the boolean parameter bool to the target Writer.

Parameters:

bool - the boolean to print on this Writer.

println

public void println()

Prints the String representation of the System property "line.separator" to the target Writer.

println

public void println(char[] charArray)

Prints the String representation of the character array parameter charArray to the target Writer followed by the System property "line.separator".

Parameters:

charArray - the character array to print on this Writer.

println

public void println(char ch)

Prints the String representation of the character parameter ch to the target Writer followed by the System property "line.separator".

Parameters:

ch - the character to print on this Writer.

println

public void println(double dnum)

Prints the String representation of the double parameter dnum to the target Writer followed by the System property "line.separator".

Parameters:

dnum - the double to print on this Writer.

println

public void println(float fnum)

Prints the String representation of the float parameter fnum to the target Writer followed by the System property "line.separator".

Parameters:

fnum - the float to print on this Writer.

println

public void println(int inum)

Prints the String representation of the int parameter inum to the target Writer followed by the System property "line.separator".

Parameters:

inum - the int to print on this Writer.

println

public void println(long lnum)

Prints the String representation of the long parameter lnum to the target Writer followed by the System property "line.separator".

Parameters:

lnum - the long to print on this Writer.

println

public void println(Object obj)

Prints the String representation of the Object parameter obj to the target Writer followed by the System property "line.separator".

Parameters:

obj - the Object to print on this Writer.

println

public void println(String str)

Prints the String representation of the String parameter str to the target Writer followed by the System property "line.separator".

Parameters:

str - the String to print on this Writer.

println

public void println(boolean bool)

Prints the String representation of the boolean parameter bool to the target Writer followed by the System property "line.separator".

Parameters:

bool - the boolean to print on this Writer.

setError

protected void setError()

Set the flag indicating that this PrintWriter has encountered an IO error.

write

public void write(char[] buf)

Writes the entire character buffer buf to this Writer.

Overrides:

write in class Writer

Parameters:

buf - the non-null array containing characters to write.

write

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

Writes count characters starting at offset in buf to this Writer.

Specified by:

write in class Writer

Parameters:

buf - the non-null array containing characters to write.

offset - offset in buf to retrieve characters

count - maximum number of characters to write

Throws:

ArrayIndexOutOfBoundsException - If offset or count are outside of bounds.

write

public void write(int oneChar)

Writes the specified character to this Writer. This implementation writes the low order two bytes to the target writer.

Overrides:

write in class Writer

Parameters:

oneChar - The character to write

write

public void write(String str)

Writes the characters from the String str to this Writer.

Overrides:

write in class Writer

Parameters:

str - the non-null String containing the characters to write.

write

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

Writes count characters from the String str starting at offset to this Writer.

Overrides:

write in class Writer

Parameters:

str - the non-null String containing the characters to write.

offset - where in str to get chars from.

count - how many characters to write.

Throws:

ArrayIndexOutOfBoundsException - If offset or count are outside of bounds.

append

public PrintWriter append(char c)

Append a char cto the PrintWriter. The PrintWriter.append(c) works the same way as PrintWriter.write(c).

Specified by:

append in interface Appendable

Overrides:

append in class Writer

Parameters:

c - The character appended to the PrintWriter.

Returns:

The PrintWriter.

append

public PrintWriter append(CharSequence csq)

Append a CharSequence csq to the PrintWriter. The PrintWriter.append(csq) works the same way as PrintWriter.write(csq.toString()). If csq is null, then "null" will be substituted for csq

Specified by:

append in interface Appendable

Overrides:

append in class Writer

Parameters:

csq - The CharSequence appended to the PrintWriter.

Returns:

The PrintWriter

append

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

Append a subsequence of a CharSequence csq to the PrintWriter. The first char and the last char of the subsequence is specified by the parameter start and end. The PrintWriter.append(csq) works the same way as PrintWriter.write(csq.subSequence(start,end).toString).If csq is null, then "null" will be substituted for csq.

Specified by:

append in interface Appendable

Overrides:

append in class Writer

Parameters:

csq - The CharSequence appended to the PrintWriter.

start - The index of the first char in the CharSequence appended to the PrintWriter.

end - The index of the char after the last one in the CharSequence appended to the PrintWriter.

Returns:

The PrintWriter.

Throws:

IndexOutOfBoundsException - If start is less than end, end is greater than the length of the CharSequence, or start or end is negative.