Class PrintWriter
- java.lang.Object
-
- java.io.Writer
-
- java.io.PrintWriter
- All Implemented Interfaces:
-
Closeable
,Flushable
,Appendable
,AutoCloseable
public class PrintWriter extends Writer
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.
- Since:
- 1.1
Field Summary
Modifier and Type | Field | Description |
---|---|---|
protected Writer | out | The underlying character-output stream of this |
Fields declared in class java.io.Writer
lock
Constructor Summary
Constructor | Description |
---|---|
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. |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
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(CharSequence csq,
int start,
int end) | Appends a subsequence of the specified character sequence to this writer. |
boolean | checkError() | Flushes the stream if it's not closed and checks its error state. |
protected void | clearError() | 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. |
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(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 | print(Object obj) | Prints an object. |
void | print(String s) | Prints a string. |
PrintWriter | printf(String format,
Object... args) | A convenience method to write a formatted string to this writer using the specified format string and arguments. |
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. |
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 | println(Object x) | Prints an Object and then terminates the line. |
void | println(String x) | 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 | write(String s) | Writes a string. |
void | write(String s,
int off,
int len) | Writes a portion of a string. |
Methods declared in class java.io.Writer
nullWriter
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Field Detail
out
protected Writer out
The underlying character-output stream of this PrintWriter
.
- Since:
- 1.2
Constructor Detail
PrintWriter
public PrintWriter(Writer out)
Creates a new PrintWriter, without automatic line flushing.
- Parameters:
-
out
- A character-output stream
PrintWriter
public PrintWriter(Writer out, boolean autoFlush)
Creates a new PrintWriter.
- Parameters:
-
out
- A character-output stream -
autoFlush
- A boolean; if true, theprintln
,printf
, orformat
methods will flush the output buffer
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
- An output stream - See Also:
OutputStreamWriter(java.io.OutputStream)
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
- An output stream -
autoFlush
- A boolean; if true, theprintln
,printf
, orformat
methods will flush the output buffer - See Also:
OutputStreamWriter(java.io.OutputStream)
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
- An output stream -
autoFlush
- A boolean; if true, theprintln
,printf
, orformat
methods will flush the output buffer -
charset
- A charset - Since:
- 10
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
- 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 andcheckWrite(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:
-
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 file -
SecurityException
- If a security manager is present andcheckWrite(fileName)
denies write access to the file -
UnsupportedEncodingException
- If the named charset is not supported - Since:
- 1.5
PrintWriter
public PrintWriter(String fileName, Charset charset) throws IOException
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
- 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 file -
SecurityException
- If a security manager is present andcheckWrite(fileName)
denies write access to the file - Since:
- 10
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
- 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 andcheckWrite(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:
-
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 file -
SecurityException
- If a security manager is present andcheckWrite(file.getPath())
denies write access to the file -
UnsupportedEncodingException
- If the named charset is not supported - Since:
- 1.5
PrintWriter
public PrintWriter(File file, Charset charset) throws IOException
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
- 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 file -
SecurityException
- If a security manager is present andcheckWrite(file.getPath())
denies write access to the file - Since:
- 10
Method Detail
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 return true
until clearError()
is invoked.
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()
.
- 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 characters -
off
- Offset from which to start writing characters -
len
- 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
public void write(String s, int off, int len)
Writes a portion of a string.
- Overrides:
-
write
in classWriter
- Parameters:
-
s
- A String -
off
- Offset from which to start writing characters -
len
- 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(String s)
Writes a string. This method cannot be inherited from the Writer class because it must suppress I/O exceptions.
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
- Theboolean
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
- Thechar
to be printed
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
- Theint
to be printed - See Also:
Integer.toString(int)
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
- Thelong
to be printed - See Also:
Long.toString(long)
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
- Thefloat
to be printed - See Also:
Float.toString(float)
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
- Thedouble
to be printed - See Also:
Double.toString(double)
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
- The array of chars to be printed - Throws:
-
NullPointerException
- Ifs
isnull
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
- TheString
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
- 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 string is defined by the system property line.separator
, 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 invokes print(boolean)
and then println()
.
- 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 invokes print(char)
and then println()
.
- 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 invokes print(int)
and then println()
.
- 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 invokes print(long)
and then println()
.
- 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 invokes print(float)
and then println()
.
- 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 invokes print(double)
and then println()
.
- 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 invokes print(char[])
and then println()
.
- Parameters:
-
x
- the array ofchar
values 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(String)
and then println()
.
- Parameters:
-
x
- theString
value to be printed
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(String)
and then println()
.
- Parameters:
-
x
- TheObject
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
- If theformat
isnull
- 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. 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
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. -
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
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. 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
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
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
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
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 subsequence -
end
- 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
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
in interfaceAppendable
- Overrides:
-
append
in classWriter
- Parameters:
-
c
- The 16-bit character to append - Returns:
- This writer
- Since:
- 1.5