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java.io
Class PrintWriter


java.lang.Object
  extended by java.io.Writer
      extended by 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
Constructor Detail

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
Method Detail

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