java.io
Class PrintWriter

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

Direct Known Subclasses:

NPrintWriter

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

Author:

Frank Yellin, Mark Reinhold

Field Summary

private boolean	autoFlush
private String	lineSeparator Line separator string.
protected Writer	out The underlying character-output stream of this PrintWriter.
private boolean	trouble

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(Writer out)
Create a new PrintWriter, without automatic line flushing.

PrintWriter(Writer out, boolean autoFlush)
Create a new PrintWriter.

Method Summary

boolean	checkError() Flush the stream if it's not closed and check its error state.
void	close() Close the stream.
private void	ensureOpen() Check to make sure that the stream has not been closed
void	flush() Flush the stream.
private void	newLine()
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.
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 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

autoFlush

private boolean autoFlush

trouble

private boolean trouble

lineSeparator

private String lineSeparator

Line separator string. This is the value of the line.separator property at the moment that the stream was created.

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)

Method Detail

ensureOpen

private void ensureOpen()
                 throws IOException

Check to make sure that the stream has not been closed

Throws:

IOException

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 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 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

newLine

private void newLine()

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