java.io
Class PrintWriter

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

All Implemented Interfaces:

Appendable , Closeable

public class PrintWriter

extends Writer

Print 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() methods is invoked, rather than whenever a newline character happens to be output. The println() methods use the platform's own notion of line separator rather than the newline character.

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

Since:

JDK1.1

Field Summary
protected   Writer	out           The underlying character-output stream of this PrintWriter.

 

Fields inherited from class java.io. Writer
lock

 

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

 

Method Summary
PrintWriter	append (char c)           Appends the specified character to this writer.
PrintWriter	append ( CharSequence           Appends the specified character sequence to this writer.
boolean	checkError ()           Flush the stream if it's not closed and check its error state.
void	close ()           Close the stream.
void	flush ()           Flush the stream.
PrintWriter	format ( Locale  l, String  format, Object           Writes a formatted string to this writer using the specified format string and arguments.
PrintWriter	format ( String  format, Object           Writes a formatted string to this writer using the specified format string and arguments.
void	print (boolean b)           Print a boolean value.
void	print (char c)           Print a character.
void	print (char[] s)           Print an array of characters.
void	print (double d)           Print a double-precision floating-point number.
void	print (float f)           Print a floating-point number.
void	print (int i)           Print an integer.
void	print (long l)           Print a long integer.
void	print ( Object  obj)           Print an object.
void	print ( String  s)           Print a string.
PrintWriter	printf ( Locale  l, String  format, Object           A convenience method to write a formatted string to this writer using the specified format string and arguments.
PrintWriter	printf ( String  format, Object           A convenience method to write a formatted string to this writer using the specified format string and arguments.
void	println ()           Terminate the current line by writing the line separator string.
void	println (boolean x)           Print a boolean value and then terminate the line.
void	println (char x)           Print a character and then terminate the line.
void	println (char[] x)           Print an array of characters and then terminate the line.
void	println (double x)           Print a double-precision floating-point number and then terminate the line.
void	println (float x)           Print a floating-point number and then terminate the line.
void	println (int x)           Print an integer and then terminate the line.
void	println (long x)           Print a long integer and then terminate the line.
void	println ( Object  x)           Print an Object and then terminate the line.
void	println ( String  x)           Print a String and then terminate the line.
protected  void	setError ()           Indicate that an error has occurred.
void	write (char[] buf)           Write an array of characters.
void	write (char[] buf, int off, int len)           Write A Portion a portion of an array of characters.
void	write (int c)           Write a single character.
void	write ( String  s)           Write a string.
void	write ( String  s, int off, int len)           Write a portion of a string.

 

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 underlying character-output stream of this PrintWriter.

Since:

1.2

PrintWriter

public PrintWriter(Writer out)

Create a new PrintWriter, without automatic line flushing.

Parameters:

out - A character-output stream

PrintWriter

public PrintWriter(Writer out,
                   boolean autoFlush)

Create a new PrintWriter.

Parameters:

out - A character-output stream

autoFlush - A boolean; if true, the println() methods will flush the output buffer

PrintWriter

public PrintWriter(OutputStream out)

Create 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)

PrintWriter

public PrintWriter(OutputStream out,
                   boolean autoFlush)

Create 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() methods will flush the output buffer

See Also:

OutputStreamWriter.OutputStreamWriter(java.io.OutputStream)

PrintWriter

 
public PrintWriter ( String fileName)
 throws FileNotFoundException

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 convert characters using the default charset.

If there is a security manager , its checkWrite method is called with fileName as its argument.

The charset used is 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 formatter. The output will be to the beginning of the file and is not buffered.

Throws:

FileNotFoundException - If the file exists but is a directory rather than a regular file, does not exist and cannot be created, or cannot be opened for any other reason

SecurityException - If a security manager exists and its checkWrite method denies write access to the file.

Since:

1.5

PrintWriter

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

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 convert characters using the provided charset.

If there is a security manager , its checkWrite method is called with fileName as its argument.

Parameters:

fileName - The name of the file to use as the destination of this formatter. The output will be to the beginning of the file and is not buffered.

csn - The name of a supported charset

Throws:

FileNotFoundException - If the file exists but is a directory rather than a regular file, does not exist and cannot be created, or cannot be opened for any other reason

SecurityException - If a security manager exists and its checkWrite method denies write access to the file.

UnsupportedEncodingException - If the named charset is not supported

Since:

1.5

flush

public void flush()

Flush the stream.

Specified by:

flush in class Writer

See Also:

checkError()

close

public void close()

Close the stream.

Specified by:

close in interface Closeable

Specified by:

close in class Writer

See Also:

checkError()

checkError

public boolean checkError()

Flush the stream if it's not closed and check its error state. Errors are cumulative; once the stream encounters an error, this routine will return true on all successive calls.

Returns:

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

setError

protected void setError()

Indicate that an error has occurred.

write

public void write(int c)

Write a single character.

Overrides:

write in class Writer

Parameters:

c - int specifying a character to be written.

write

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

Write A Portion a portion of an array of characters.

Specified by:

write in class Writer

Parameters:

buf - Array of characters

off - Offset from which to start writing characters

len - Number of characters to write

write

public void write(char[] buf)

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

Overrides:

write in class Writer

Parameters:

buf - Array of characters to be written

write

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

Write a portion of a string.

Overrides:

write in class Writer

Parameters:

s - A String

off - Offset from which to start writing characters

len - Number of characters to write

write

public void write(String s)

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

Overrides:

write in class Writer

Parameters:

s - String to be written

print

public void print(boolean b)

Print 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

print

public void print(char c)

Print 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

print

public void print(int i)

Print 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)

print

public void print(long l)

Print 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)

print

public void print(float f)

Print 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)

print

public void print(double d)

Print 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)

print

public void print(char[] s)

Print 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

print

public void print(String s)

Print 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

print

public void print(Object obj)

Print 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()

println

public void println()

Terminate 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').

println

public void println(boolean x)

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

Parameters:

x - the boolean value to be printed

println

public void println(char x)

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

Parameters:

x - the char value to be printed

println

public void println(int x)

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

Parameters:

x - the int value to be printed

println

public void println(long x)

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

Parameters:

x - the long value to be printed

println

public void println(float x)

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

Parameters:

x - the float value to be printed

println

public void println(double x)

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

Parameters:

x - the double value to be printed

println

public void println(char[] x)

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

Parameters:

x - the array of char values to be printed

println

public void println(String x)

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

Parameters:

x - the String value to be printed

println

public void println(Object x)

Print an Object and then terminate the line. This method behaves as though it invokes print(Object) and then println() .

Parameters:

x - the Object value to be printed

printf

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

A convenience method to write a formatted string to this writer using the specified format string and arguments.

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

Since:

1.5

printf

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

A convenience method to write a formatted string to this writer using the specified format string and arguments.

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 durring 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

Since:

1.5

format

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

Writes a formatted string to this writer using the specified format string and arguments.

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

Since:

1.5

format

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

Writes a formatted string to this writer using the specified format string and arguments.

Parameters:

l - The locale to apply durring 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

Since:

1.5

append

 
public PrintWriterappend ( CharSequence csq)
 throws IOException

Description copied from class: Writer

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.

Specified by:

append in interface Appendable

Overrides:

append in class Writer

Parameters:

csq - The character sequence to append. If csq is null , then the four characters "null" are appended to this text-output stream.

Returns:

This writer

Throws:

IOException - If an I/O error occurs

append

 
public PrintWriterappend (char c)
 throws IOException

Description copied from class: Writer

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) 

Specified by:

append in interface Appendable

Overrides:

append in class Writer

Parameters:

c - The 16-bit character to append

Returns:

This writer

Throws:

IOException - If an I/O error occurs