PrintWriter
public
class
PrintWriter
extends Writer
java.lang.Object | ||
↳ | java.io.Writer | |
↳ | java.io.PrintWriter |
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()
.
This class always replaces malformed and unmappable character sequences with the charset's default replacement string. The CharsetEncoder class should be used when more control over the encoding process is required.
Summary
Fields | |
---|---|
protected
Writer |
out
The underlying character-output stream of this
|
Inherited fields |
---|
Public constructors | |
---|---|
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. |
|
PrintWriter(File file, Charset charset)
Creates a new PrintWriter, without automatic line flushing, with the specified file and charset. |
|
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(OutputStream out, boolean autoFlush, Charset charset)
Creates a new PrintWriter from an existing OutputStream. |
|
PrintWriter(Writer out)
Creates a new PrintWriter, without automatic line flushing. |
|
PrintWriter(Writer out, boolean autoFlush)
Creates a new PrintWriter. |
|
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(String fileName, Charset charset)
Creates a new PrintWriter, without automatic line flushing, with the specified file name 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(String format, Object... args)
Writes a formatted string to this writer using the specified format string and arguments. |
PrintWriter
|
format(Locale l, String format, Object... args)
Writes a formatted string to this writer using the specified format string and arguments. |
void
|
print(double d)
Prints a double-precision floating-point number. |
void
|
print(int i)
Prints an integer. |
void
|
print(boolean b)
Prints a boolean value. |
void
|
print(char c)
Prints a character. |
void
|
print(long l)
Prints a long integer. |
void
|
print(float f)
Prints a floating-point number. |
void
|
print(String s)
Prints a string. |
void
|
print(Object obj)
Prints an object. |
void
|
print(char[] s)
Prints an array of characters. |
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(Object x)
Prints an Object and then terminates the line. |
void
|
println(char x)
Prints a character and then terminates the line. |
void
|
println(boolean x)
Prints a boolean value and then terminates the line. |
void
|
println(long x)
Prints a long integer and then terminates the line. |
void
|
println()
Terminates the current line by writing the line separator string. |
void
|
println(int x)
Prints an integer and then terminates the line. |
void
|
println(String x)
Prints a String and then terminates the line. |
void
|
println(char[] x)
Prints an array of characters and then terminates the line. |
void
|
println(float x)
Prints a floating-point number and then terminates the line. |
void
|
println(double x)
Prints a double-precision floating-point number and then terminates the line. |
void
|
write(int c)
Writes a single character. |
void
|
write(char[] buf, int off, int len)
Writes A Portion of an array of characters. |
void
|
write(String s)
Writes a string. |
void
|
write(String s, int off, int len)
Writes a portion of a string. |
void
|
write(char[] buf)
Writes an array of characters. |
Protected methods | |
---|---|
void
|
clearError()
Clears the error state of this stream. |
void
|
setError()
Indicates that an error has occurred. |
Inherited methods | |
---|---|
Fields
out
protected Writer out
The underlying character-output stream of this
PrintWriter
.
Public constructors
PrintWriter
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 |
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 |
PrintWriter
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 |
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 |
String : 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 |
PrintWriter
public PrintWriter (File file, Charset charset)
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 |
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. |
charset |
Charset : A charset |
Throws | |
---|---|
IOException |
if an I/O 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 |
PrintWriter
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 |
OutputStream : An output stream |
PrintWriter
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 |
OutputStream : An output stream |
autoFlush |
boolean : A boolean; if true, the println ,
printf , or format methods will
flush the output buffer |
PrintWriter
public PrintWriter (OutputStream out, boolean autoFlush, Charset charset)
Creates a new PrintWriter from an existing OutputStream. This convenience constructor creates the necessary intermediate OutputStreamWriter, which will convert characters into bytes using the specified charset.
Parameters | |
---|---|
out |
OutputStream : An output stream |
autoFlush |
boolean : A boolean; if true, the println ,
printf , or format methods will
flush the output buffer |
charset |
Charset : A charset |
PrintWriter
public PrintWriter (Writer out)
Creates a new PrintWriter, without automatic line flushing.
Parameters | |
---|---|
out |
Writer : A character-output stream |
PrintWriter
public PrintWriter (Writer out, boolean autoFlush)
Creates a new PrintWriter.
Parameters | |
---|---|
out |
Writer : A character-output stream |
autoFlush |
boolean : A boolean; if true, the println,
printf, or format methods will
flush the output buffer |
PrintWriter
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 |
String : 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 |
PrintWriter
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 |
String : 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 |
String : 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 |
PrintWriter
public PrintWriter (String fileName, Charset charset)
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 |
String : 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. |
charset |
Charset : A charset |
Throws | |
---|---|
IOException |
if an I/O 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 methods
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)
Parameters | |
---|---|
c |
char : The 16-bit character to append |
Returns | |
---|---|
PrintWriter |
This writer |
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())
Parameters | |
---|---|
csq |
CharSequence : 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 |
int : The index of the first character in the subsequence |
end |
int : The index of the character following the last character in the
subsequence |
Returns | |
---|---|
PrintWriter |
This writer |
Throws | |
---|---|
IndexOutOfBoundsException |
If start or end are negative, start
is greater than end , or end is greater than
csq.length() |
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.
Parameters | |
---|---|
csq |
CharSequence : The character sequence to append. If csq is
null , then the four characters "null" are
appended to this writer. |
Returns | |
---|---|
PrintWriter |
This writer |
checkError
public boolean checkError ()
Flushes the stream if it's not closed and checks its error state.
Returns | |
---|---|
boolean |
true if the print stream has encountered an error,
either on the underlying output stream or during a format
conversion. |
close
public void close ()
Closes the stream and releases any system resources associated with it. Closing a previously closed stream has no effect.
See also:
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 |
String : A format string as described in Format string syntax. |
args |
Object : 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 | |
---|---|
PrintWriter |
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 |
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 |
Locale : The locale to apply during
formatting. If l is null then no localization
is applied. |
format |
String : A format string as described in Format string syntax. |
args |
Object : 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 | |
---|---|
PrintWriter |
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 |
public void print (double d)
Prints 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 |
double : The double to be printed |
See also:
public void print (int i)
Prints 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 |
int : The int to be printed |
See also:
public void print (boolean b)
Prints 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 |
boolean : The boolean to be printed |
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 |
char : The char to be printed |
public void print (long l)
Prints 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 |
long : The long to be printed |
See also:
public void print (float f)
Prints 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 |
float : The float 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 |
String : The String to be printed |
public void print (Object obj)
Prints 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 |
Object : The Object to be printed |
See also:
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 |
char : The array of chars to be printed |
Throws | |
---|---|
NullPointerException |
If s is null |
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 |
Locale : The locale to apply during
formatting. If l is null then no localization
is applied. |
format |
String : A format string as described in Format string syntax. |
args |
Object : 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 | |
---|---|
PrintWriter |
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 |
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 |
String : A format string as described in Format string syntax. |
args |
Object : 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 | |
---|---|
PrintWriter |
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 |
println
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(java.lang.String)
and then
println()
.
Parameters | |
---|---|
x |
Object : The Object to be printed. |
println
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 |
char : the char value to be printed |
println
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 |
boolean : the boolean value to be printed |
println
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 |
long : the long value to be printed |
println
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'
).
println
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 |
int : the int value to be printed |
println
public void println (String x)
Prints a String and then terminates the line. This method behaves as
though it invokes print(java.lang.String)
and then
println()
.
Parameters | |
---|---|
x |
String : the String value to be printed |
println
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 |
char : the array of char values to be printed |
println
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 |
float : the float value to be printed |
println
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 |
double : the double value to be printed |
write
public void write (int c)
Writes a single character.
Parameters | |
---|---|
c |
int : int specifying a character to be written. |
write
public void write (char[] buf, int off, int len)
Writes A Portion of an array of characters.
Parameters | |
---|---|
buf |
char : Array of characters |
off |
int : Offset from which to start writing characters |
len |
int : Number of characters to write |
Throws | |
---|---|
IndexOutOfBoundsException |
If the values of the off and len parameters
cause the corresponding method of the underlying Writer
to throw an IndexOutOfBoundsException |
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 : String to be written |
write
public void write (String s, int off, int len)
Writes a portion of a string.
Parameters | |
---|---|
s |
String : A String |
off |
int : Offset from which to start writing characters |
len |
int : Number of characters to write |
Throws | |
---|---|
IndexOutOfBoundsException |
If the values of the off and len parameters
cause the corresponding method of the underlying Writer
to throw an IndexOutOfBoundsException |
write
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 |
char : Array of characters to be written |
Protected methods
clearError
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()
.
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.