public class

PrintWriter

extends Writer
java.lang.Object
   ↳ java.io.Writer
     ↳ java.io.PrintWriter
Known Direct Subclasses

Class Overview

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().

Summary

Fields
protected Writer out The underlying character-output stream of this PrintWriter.
[Expand]
Inherited Fields
From class java.io.Writer
Public Constructors
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 Methods
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(float f)
Prints a floating-point number.
void print(double d)
Prints a double-precision floating-point number.
void print(String s)
Prints a string.
void print(Object obj)
Prints an object.
void print(char c)
Prints a character.
void print(char[] s)
Prints an array of characters.
void print(long l)
Prints a long integer.
void print(int i)
Prints an integer.
void print(boolean b)
Prints a boolean value.
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.
PrintWriter printf(String format, Object... args)
A convenience method to write a formatted string to this writer using the specified format string and arguments.
void println()
Terminates the current line by writing the line separator string.
void println(float x)
Prints a floating-point number and then terminates the line.
void println(int x)
Prints an integer and then terminates the line.
void println(long x)
Prints a long integer and then terminates the line.
void println(Object x)
Prints an Object and then terminates the line.
void println(char[] x)
Prints an array of characters and then terminates the line.
void println(String x)
Prints a String and then terminates the line.
void println(char x)
Prints a character and then terminates the line.
void println(double x)
Prints a double-precision floating-point number and then terminates the line.
void println(boolean x)
Prints a boolean value and then terminates the line.
void write(char[] buf, int off, int len)
Writes A Portion of an array of characters.
void write(int c)
Writes a single character.
void write(char[] buf)
Writes an array of characters.
void write(String s, int off, int len)
Writes a portion of a string.
void write(String s)
Writes a string.
Protected Methods
void clearError()
Clears the error state of this stream.
void setError()
Indicates that an error has occurred.
[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 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

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

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 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 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 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 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

public void flush ()

Flushes the stream.

See Also

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 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
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
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 (float f)

Prints a floating-point number. The string produced by 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

public void print (double d)

Prints a double-precision floating-point number. The string produced by 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

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 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

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 (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 void print (long l)

Prints a long integer. The string produced by 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

public void print (int i)

Prints an integer. The string produced by 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

public void print (boolean b)

Prints a boolean value. The string produced by 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 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 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
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 (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
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 ()

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 (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 (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 (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 (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 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 (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 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 (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 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 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 (int c)

Writes a single character.

Parameters
c int specifying a character to be written.

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

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 (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

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.