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public class

PrintWriter

extends Writer
java.lang.Object
   ↳ java.io.Writer
     ↳ java.io.PrintWriter

Class Overview

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.

Summary

Fields
protected Writer out The writer to output data to.
[Expand]
Inherited Fields
From class java.io.Writer
Public Constructors
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(Writer wr)
Constructs a new PrintWriter on the Writer wr.
PrintWriter(Writer wr, boolean autoflush)
Constructs a new PrintWriter on the given writer.
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(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.
Public Methods
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(String format, Object... args)
Writes a string formatted by an intermediate Formatter to this writer using the given format string and arguments.
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.
void print(float fnum)
Prints the String representation of the float parameter fnum to the target Writer.
void print(char ch)
Prints the String representation of the character parameter ch 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.
void print(int inum)
Prints the String representation of the int parameter inum to the target Writer.
void print(double dnum)
Prints the String representation of the double parameter dnum to the target Writer.
void print(long lnum)
Prints the String representation of the long parameter lnum to the target Writer.
void print(char[] charArray)
Prints the String representation of the character array parameter charArray to the target Writer.
void print(boolean bool)
Prints the String representation of the boolean parameter bool 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(double dnum)
Prints the String representation of the double parameter dnum 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".
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(long lnum)
Prints the String representation of the long parameter lnum 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(float fnum)
Prints the String representation of the float parameter fnum 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(Object obj)
Prints the String representation of the Object parameter obj to the target Writer followed by the System property "line.separator".
void println()
Prints the String representation of the System property "line.separator" to the target Writer.
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 write(char[] buf)
Writes the entire character buffer buf 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.
void write(int oneChar)
Writes the specified character to this Writer.
void write(char[] buf, int offset, int count)
Writes count characters starting at offset in buf to this Writer.
Protected Methods
void setError()
Set the flag indicating that this PrintWriter has encountered an IO error.
[Expand]
Inherited Methods
From class java.io.Writer
From class java.lang.Object
From interface java.io.Closeable
From interface java.io.Flushable
From interface java.lang.Appendable

Fields

protected Writer out

The writer to output data to.

Public Constructors

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.

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.

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.

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.

public PrintWriter (File file)

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.

public PrintWriter (File file, String csn)

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.

public PrintWriter (String fileName)

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.

public PrintWriter (String fileName, String csn)

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.

Public Methods

public PrintWriter append (char c)

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

Parameters
c The character appended to the PrintWriter.
Returns
  • The PrintWriter.

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

Parameters
csq The CharSequence appended to the PrintWriter.
Returns
  • The PrintWriter

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

public void println ()

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

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.

public void write (char[] buf)

Writes the entire character buffer buf to this Writer.

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

public void write (String str)

Writes the characters from the String str to this Writer.

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

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

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

public void write (int oneChar)

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

Parameters
oneChar The character to write

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

Writes count characters starting at offset in buf to this 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.

Protected Methods

protected void setError ()

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