PrintWriter (Java 2 Platform SE 5.0) (original) (raw)

java.io

Class PrintWriter

java.lang.Object extended by java.io.Writer java.io.PrintWriter

All Implemented Interfaces:

public class PrintWriter

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, printf, orformat 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().

Since:

JDK1.1

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

Fields inherited from class java.io.Writer
lock

Constructor Summary
PrintWriter(File file) Creates a new PrintWriter, without automatic line flushing, with the specified file.
[PrintWriter](../../java/io/PrintWriter.html#PrintWriter%28java.io.File, java.lang.String%29)(File file,String csn) Creates a new PrintWriter, without automatic line flushing, with the specified file and charset.
PrintWriter(OutputStream out) Create a new PrintWriter, without automatic line flushing, from an existing OutputStream.
[PrintWriter](../../java/io/PrintWriter.html#PrintWriter%28java.io.OutputStream, boolean%29)(OutputStream out, boolean autoFlush) Create a new PrintWriter from an existing OutputStream.
PrintWriter(String fileName) Creates a new PrintWriter, without automatic line flushing, with the specified file name.
[PrintWriter](../../java/io/PrintWriter.html#PrintWriter%28java.lang.String, java.lang.String%29)(String fileName,String csn) 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](../../java/io/PrintWriter.html#PrintWriter%28java.io.Writer, boolean%29)(Writer out, boolean autoFlush) Create a new PrintWriter.

Method Summary
PrintWriter	append(char c) Appends the specified character to this writer.
PrintWriter	append(CharSequence csq) Appends the specified character sequence to this writer.
PrintWriter	[append](../../java/io/PrintWriter.html#append%28java.lang.CharSequence, int, int%29)(CharSequence csq, int start, int end) Appends a subsequence of 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](../../java/io/PrintWriter.html#format%28java.util.Locale, java.lang.String, java.lang.Object...%29)(Locale l,String format,Object... args) Writes a formatted string to this writer using the specified format string and arguments.
PrintWriter	[format](../../java/io/PrintWriter.html#format%28java.lang.String, java.lang.Object...%29)(String format,Object... args) 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](../../java/io/PrintWriter.html#printf%28java.util.Locale, java.lang.String, java.lang.Object...%29)(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](../../java/io/PrintWriter.html#printf%28java.lang.String, java.lang.Object...%29)(String format,Object... args) 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](../../java/io/PrintWriter.html#write%28char[], int, int%29)(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](../../java/io/PrintWriter.html#write%28java.lang.String, int, int%29)(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](../../java/lang/Object.html#wait%28long, int%29)

Field Detail

out

protected Writer out

The underlying character-output stream of thisPrintWriter.

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,printf, or format 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

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,printf, or format methods will flush the output buffer

PrintWriter

public PrintWriter(String fileName) throws FileNotFoundException

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](../../java/io/FileNotFoundException.html "class in java.io") - 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](../../java/lang/SecurityException.html "class in java.lang") - If a security manager is present and checkWrite(fileName) 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 encode characters using the provided charset.

Parameters:

csn - The name of a supported charset

Throws:

[SecurityException](../../java/lang/SecurityException.html "class in java.lang") - If a security manager is present and checkWrite(fileName) denies write access to the file

[UnsupportedEncodingException](../../java/io/UnsupportedEncodingException.html "class in java.io") - If the named charset is not supported

Since:

1.5

PrintWriter

public PrintWriter(File file) throws FileNotFoundException

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](../../java/io/FileNotFoundException.html "class in java.io") - 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](../../java/lang/SecurityException.html "class in java.lang") - If a security manager is present and checkWrite(file.getPath()) denies write access to the file

Since:

1.5

PrintWriter

public PrintWriter(File file, String csn) throws FileNotFoundException, UnsupportedEncodingException

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:

csn - The name of a supported charset

Throws:

[SecurityException](../../java/lang/SecurityException.html "class in java.lang") - If a security manager is present and checkWrite(file.getPath()) denies write access to the file

[UnsupportedEncodingException](../../java/io/UnsupportedEncodingException.html "class in java.io") - If the named charset is not supported

Since:

1.5

Method Detail

flush

public void flush()

Flush the stream.

Specified by:

[flush](../../java/io/Flushable.html#flush%28%29) in interface [Flushable](../../java/io/Flushable.html "interface in java.io")

Specified by:

[flush](../../java/io/Writer.html#flush%28%29) in class [Writer](../../java/io/Writer.html "class in java.io")

See Also:

checkError()

close

public void close()

Close the stream.

Specified by:

[close](../../java/io/Closeable.html#close%28%29) in interface [Closeable](../../java/io/Closeable.html "interface in java.io")

Specified by:

[close](../../java/io/Writer.html#close%28%29) in class [Writer](../../java/io/Writer.html "class in java.io")

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](../../java/io/Writer.html#write%28int%29) in class [Writer](../../java/io/Writer.html "class in java.io")

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](../../java/io/Writer.html#write%28char[], int, int%29) in class [Writer](../../java/io/Writer.html "class in java.io")

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](../../java/io/Writer.html#write%28char[]%29) in class [Writer](../../java/io/Writer.html "class in java.io")

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](../../java/io/Writer.html#write%28java.lang.String, int, int%29) in class [Writer](../../java/io/Writer.html "class in java.io")

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](../../java/io/Writer.html#write%28java.lang.String%29) in class [Writer](../../java/io/Writer.html "class in java.io")

Parameters:

s - String to be written

print

public void print(boolean b)

Print a boolean value. The string produced by [String.valueOf(boolean)](../../java/lang/String.html#valueOf%28boolean%29) 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)](../../java/io/PrintWriter.html#write%28int%29) 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)](../../java/io/PrintWriter.html#write%28int%29) method.

Parameters:

c - The char to be printed

print

public void print(int i)

Print an integer. The string produced by [String.valueOf(int)](../../java/lang/String.html#valueOf%28int%29) 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)](../../java/io/PrintWriter.html#write%28int%29) 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)](../../java/lang/String.html#valueOf%28long%29) 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)](../../java/io/PrintWriter.html#write%28int%29) 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)](../../java/lang/String.html#valueOf%28float%29) 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)](../../java/io/PrintWriter.html#write%28int%29) 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)](../../java/lang/String.html#valueOf%28double%29) 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)](../../java/io/PrintWriter.html#write%28int%29) 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)](../../java/io/PrintWriter.html#write%28int%29) method.

Parameters:

s - The array of chars to be printed

Throws:

[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - 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)](../../java/io/PrintWriter.html#write%28int%29) 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)](../../java/lang/String.html#valueOf%28java.lang.Object%29) 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)](../../java/io/PrintWriter.html#write%28int%29) 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 propertyline.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)](../../java/io/PrintWriter.html#print%28boolean%29) and then[println()](../../java/io/PrintWriter.html#println%28%29).

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)](../../java/io/PrintWriter.html#print%28char%29) and then [println()](../../java/io/PrintWriter.html#println%28%29).

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)](../../java/io/PrintWriter.html#print%28int%29) and then [println()](../../java/io/PrintWriter.html#println%28%29).

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)](../../java/io/PrintWriter.html#print%28long%29) and then[println()](../../java/io/PrintWriter.html#println%28%29).

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)](../../java/io/PrintWriter.html#print%28float%29) and then[println()](../../java/io/PrintWriter.html#println%28%29).

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)](../../java/io/PrintWriter.html#print%28double%29) and then [println()](../../java/io/PrintWriter.html#println%28%29).

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[])](../../java/io/PrintWriter.html#print%28char[]%29) and then[println()](../../java/io/PrintWriter.html#println%28%29).

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)](../../java/io/PrintWriter.html#print%28java.lang.String%29) and then[println()](../../java/io/PrintWriter.html#println%28%29).

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)](../../java/io/PrintWriter.html#print%28java.lang.Object%29) and then[println()](../../java/io/PrintWriter.html#println%28%29).

Parameters:

x - the Object value to be printed

printf

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 anull 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](../../java/lang/NullPointerException.html "class in java.lang") - If the format is null

Since:

1.5

printf

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.

Returns:

This writer

Throws:

[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - If the format is null

Since:

1.5

format

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.

Returns:

This writer

Throws:

[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - If the format is null

Since:

1.5

format

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.

Returns:

This writer

Throws:

[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - If the format is null

Since:

1.5

append

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.

Specified by:

[append](../../java/lang/Appendable.html#append%28java.lang.CharSequence%29) in interface [Appendable](../../java/lang/Appendable.html "interface in java.lang")

Overrides:

[append](../../java/io/Writer.html#append%28java.lang.CharSequence%29) in class [Writer](../../java/io/Writer.html "class in java.io")

Parameters:

csq - The character sequence to append. If csq isnull, then the four characters "null" are appended to this writer.

Returns:

This writer

Since:

1.5

append

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())

Specified by:

[append](../../java/lang/Appendable.html#append%28java.lang.CharSequence, int, int%29) in interface [Appendable](../../java/lang/Appendable.html "interface in java.lang")

Overrides:

[append](../../java/io/Writer.html#append%28java.lang.CharSequence, int, int%29) in class [Writer](../../java/io/Writer.html "class in java.io")

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](../../java/lang/IndexOutOfBoundsException.html "class in java.lang") - If start or end are negative, start is greater than end, or end is greater thancsq.length()

Since:

1.5

append

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)

Specified by:

[append](../../java/lang/Appendable.html#append%28char%29) in interface [Appendable](../../java/lang/Appendable.html "interface in java.lang")

Overrides:

[append](../../java/io/Writer.html#append%28char%29) in class [Writer](../../java/io/Writer.html "class in java.io")

Parameters:

c - The 16-bit character to append

Returns:

This writer

Since:

1.5

Submit a bug or feature
For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.