- All Implemented Interfaces:
Closeable
,Flushable
,Appendable
,AutoCloseable
public class PrintWriter extends Writer
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.
- Since:
- 1.1
-
Field Summary
Modifier and TypeFieldDescriptionprotected Writer
The underlying character-output stream of thisPrintWriter
. -
Constructor Summary
ConstructorDescriptionPrintWriter(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. -
Method Summary
Modifier and TypeMethodDescriptionappend(char c)
Appends the specified character to this writer.append(CharSequence csq)
Appends the specified character sequence to this writer.append(CharSequence csq, int start, int end)
Appends a subsequence of the specified character sequence to this writer.boolean
Flushes the stream if it's not closed and checks its error state.protected void
Clears the error state of this stream.void
close()
Closes the stream and releases any system resources associated with it.void
flush()
Flushes the stream.Writes a formatted string to this writer using the specified format string and arguments.Writes a formatted string to this writer using the specified format string and arguments.void
print(boolean b)
Prints a boolean value.void
print(char c)
Prints a character.void
print(char[] s)
Prints an array of characters.void
print(double d)
Prints a double-precision floating-point number.void
print(float f)
Prints a floating-point number.void
print(int i)
Prints an integer.void
print(long l)
Prints a long integer.void
Prints an object.void
Prints a string.A convenience method to write a formatted string to this writer using the specified format string and arguments.A convenience method to write a formatted string to this writer using the specified format string and arguments.void
println()
Terminates the current line by writing the line separator string.void
println(boolean x)
Prints a boolean value and then terminates the line.void
println(char x)
Prints a character and then terminates the line.void
println(char[] x)
Prints an array of characters and then terminates the line.void
println(double x)
Prints a double-precision floating-point number and then terminates the line.void
println(float x)
Prints a floating-point number and then terminates the line.void
println(int x)
Prints an integer and then terminates the line.void
println(long x)
Prints a long integer and then terminates the line.void
Prints an Object and then terminates the line.void
Prints a String and then terminates the line.protected void
setError()
Indicates that an error has occurred.void
write(char[] buf)
Writes an array of characters.void
write(char[] buf, int off, int len)
Writes A Portion of an array of characters.void
write(int c)
Writes a single character.void
Writes a string.void
Writes a portion of a string.Methods declared in class java.io.Writer
nullWriter
-
Field Details
-
out
The underlying character-output stream of thisPrintWriter
.- Since:
- 1.2
-
-
Constructor Details
-
PrintWriter
Creates a new PrintWriter, without automatic line flushing.- Parameters:
out
- A character-output stream
-
PrintWriter
Creates a new PrintWriter.- Parameters:
out
- A character-output streamautoFlush
- A boolean; if true, theprintln
,printf
, orformat
methods will flush the output buffer
-
PrintWriter
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
- An output stream- See Also:
OutputStreamWriter(java.io.OutputStream)
-
PrintWriter
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
- An output streamautoFlush
- A boolean; if true, theprintln
,printf
, orformat
methods will flush the output buffer- See Also:
OutputStreamWriter(java.io.OutputStream)
-
PrintWriter
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
- An output streamautoFlush
- A boolean; if true, theprintln
,printf
, orformat
methods will flush the output buffercharset
- A charset- Since:
- 10
-
PrintWriter
Creates a new PrintWriter, without automatic line flushing, with the specified file name. This convenience constructor creates the necessary intermediateOutputStreamWriter
, 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
- 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 fileSecurityException
- If a security manager is present andcheckWrite(fileName)
denies write access to the file- Since:
- 1.5
-
PrintWriter
public PrintWriter(String fileName, String csn) throws FileNotFoundException, UnsupportedEncodingExceptionCreates a new PrintWriter, without automatic line flushing, with the specified file name and charset. This convenience constructor creates the necessary intermediateOutputStreamWriter
, which will encode characters using the provided charset.- 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.csn
- 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 fileSecurityException
- If a security manager is present andcheckWrite(fileName)
denies write access to the fileUnsupportedEncodingException
- If the named charset is not supported- Since:
- 1.5
-
PrintWriter
Creates a new PrintWriter, without automatic line flushing, with the specified file name and charset. This convenience constructor creates the necessary intermediateOutputStreamWriter
, which will encode characters using the provided charset.- 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.charset
- A charset- Throws:
IOException
- if an I/O error occurs while opening or creating the fileSecurityException
- If a security manager is present andcheckWrite(fileName)
denies write access to the file- Since:
- 10
-
PrintWriter
Creates a new PrintWriter, without automatic line flushing, with the specified file. This convenience constructor creates the necessary intermediateOutputStreamWriter
, 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
- 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 fileSecurityException
- If a security manager is present andcheckWrite(file.getPath())
denies write access to the file- Since:
- 1.5
-
PrintWriter
public PrintWriter(File file, String csn) throws FileNotFoundException, UnsupportedEncodingExceptionCreates a new PrintWriter, without automatic line flushing, with the specified file and charset. This convenience constructor creates the necessary intermediateOutputStreamWriter
, which will encode characters using the provided charset.- 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.csn
- 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 fileSecurityException
- If a security manager is present andcheckWrite(file.getPath())
denies write access to the fileUnsupportedEncodingException
- If the named charset is not supported- Since:
- 1.5
-
PrintWriter
Creates a new PrintWriter, without automatic line flushing, with the specified file and charset. This convenience constructor creates the necessary intermediateOutputStreamWriter
, which will encode characters using the provided charset.- 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.charset
- A charset- Throws:
IOException
- if an I/O error occurs while opening or creating the fileSecurityException
- If a security manager is present andcheckWrite(file.getPath())
denies write access to the file- Since:
- 10
-
-
Method Details
-
flush
public void flush()Flushes the stream.- Specified by:
flush
in interfaceFlushable
- Specified by:
flush
in classWriter
- See Also:
checkError()
-
close
public void close()Closes the stream and releases any system resources associated with it. Closing a previously closed stream has no effect.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Specified by:
close
in classWriter
- See Also:
checkError()
-
checkError
public boolean checkError()Flushes the stream if it's not closed and checks its error state.- 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()Indicates that an error has occurred.This method will cause subsequent invocations of
checkError()
to returntrue
untilclearError()
is invoked. -
clearError
protected void clearError()Clears the error state of this stream.This method will cause subsequent invocations of
checkError()
to returnfalse
until another write operation fails and invokessetError()
.- Since:
- 1.6
-
write
public void write(int c)Writes a single character. -
write
public void write(char[] buf, int off, int len)Writes A Portion of an array of characters.- Specified by:
write
in classWriter
- Parameters:
buf
- Array of charactersoff
- Offset from which to start writing characterslen
- Number of characters to write- Throws:
IndexOutOfBoundsException
- If the values of theoff
andlen
parameters cause the corresponding method of the underlyingWriter
to throw anIndexOutOfBoundsException
-
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. -
write
Writes a portion of a string.- Overrides:
write
in classWriter
- Parameters:
s
- A Stringoff
- Offset from which to start writing characterslen
- Number of characters to write- Throws:
IndexOutOfBoundsException
- If the values of theoff
andlen
parameters cause the corresponding method of the underlyingWriter
to throw anIndexOutOfBoundsException
-
write
Writes a string. This method cannot be inherited from the Writer class because it must suppress I/O exceptions. -
print
public void print(boolean b)Prints a boolean value. The string produced byString.valueOf(boolean)
is translated into bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of thewrite(int)
method.- Parameters:
b
- Theboolean
to be printed
-
print
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 thewrite(int)
method.- Parameters:
c
- Thechar
to be printed
-
print
public void print(int i)Prints an integer. The string produced byString.valueOf(int)
is translated into bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of thewrite(int)
method.- Parameters:
i
- Theint
to be printed- See Also:
Integer.toString(int)
-
print
public void print(long l)Prints a long integer. The string produced byString.valueOf(long)
is translated into bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of thewrite(int)
method.- Parameters:
l
- Thelong
to be printed- See Also:
Long.toString(long)
-
print
public void print(float f)Prints a floating-point number. The string produced byString.valueOf(float)
is translated into bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of thewrite(int)
method.- Parameters:
f
- Thefloat
to be printed- See Also:
Float.toString(float)
-
print
public void print(double d)Prints a double-precision floating-point number. The string produced byString.valueOf(double)
is translated into bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of thewrite(int)
method.- Parameters:
d
- Thedouble
to be printed- See Also:
Double.toString(double)
-
print
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 thewrite(int)
method.- Parameters:
s
- The array of chars to be printed- Throws:
NullPointerException
- Ifs
isnull
-
print
Prints a string. If the argument isnull
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 thewrite(int)
method.- Parameters:
s
- TheString
to be printed
-
print
Prints an object. The string produced by theString.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 thewrite(int)
method.- Parameters:
obj
- TheObject
to be printed- See Also:
Object.toString()
-
println
public void println()Terminates the current line by writing the line separator string. The line separator isSystem.lineSeparator()
and is not necessarily a single newline character ('\n'
). -
println
public void println(boolean x)Prints a boolean value and then terminates the line. This method behaves as though it invokesprint(boolean)
and thenprintln()
.- Parameters:
x
- theboolean
value to be printed
-
println
public void println(char x)Prints a character and then terminates the line. This method behaves as though it invokesprint(char)
and thenprintln()
.- Parameters:
x
- thechar
value to be printed
-
println
public void println(int x)Prints an integer and then terminates the line. This method behaves as though it invokesprint(int)
and thenprintln()
.- Parameters:
x
- theint
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 invokesprint(long)
and thenprintln()
.- Parameters:
x
- thelong
value 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 invokesprint(float)
and thenprintln()
.- Parameters:
x
- thefloat
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 invokesprint(double)
and thenprintln()
.- Parameters:
x
- thedouble
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 invokesprint(char[])
and thenprintln()
.- Parameters:
x
- the array ofchar
values to be printed
-
println
Prints a String and then terminates the line. This method behaves as though it invokesprint(String)
and thenprintln()
.- Parameters:
x
- theString
value to be printed
-
println
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 invokesprint(String)
and thenprintln()
.- Parameters:
x
- TheObject
to be printed.
-
printf
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 invocationout.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
- If theformat
isnull
- Since:
- 1.5
-
printf
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 invocationout.format(l, format, args)
- Parameters:
l
- The locale to apply during formatting. Ifl
isnull
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 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
- If theformat
isnull
- Since:
- 1.5
-
format
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.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
- If theformat
isnull
- Since:
- 1.5
-
format
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. Ifl
isnull
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 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
- If theformat
isnull
- Since:
- 1.5
-
append
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 invocationout.write(csq.toString())
Depending on the specification of
toString
for the character sequencecsq
, the entire sequence may not be appended. For instance, invoking thetoString
method of a character buffer will return a subsequence whose content depends upon the buffer's position and limit.- Specified by:
append
in interfaceAppendable
- Overrides:
append
in classWriter
- Parameters:
csq
- The character sequence to append. Ifcsq
isnull
, then the four characters"null"
are appended to this writer.- Returns:
- This writer
- Since:
- 1.5
-
append
Appends a subsequence of the specified character sequence to this writer.An invocation of this method of the form
out.append(csq, start, end)
whencsq
is notnull
, behaves in exactly the same way as the invocationout.write(csq.subSequence(start, end).toString())
- Specified by:
append
in interfaceAppendable
- Overrides:
append
in classWriter
- Parameters:
csq
- The character sequence from which a subsequence will be appended. Ifcsq
isnull
, then characters will be appended as ifcsq
contained the four characters"null"
.start
- The index of the first character in the subsequenceend
- The index of the character following the last character in the subsequence- Returns:
- This writer
- Throws:
IndexOutOfBoundsException
- Ifstart
orend
are negative,start
is greater thanend
, orend
is greater thancsq.length()
- Since:
- 1.5
-
append
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 invocationout.write(c)
- Specified by:
append
in interfaceAppendable
- Overrides:
append
in classWriter
- Parameters:
c
- The 16-bit character to append- Returns:
- This writer
- Since:
- 1.5
-