Class PrintWriter
- All Implemented Interfaces:
- Closeable,- Flushable,- Appendable,- AutoCloseable
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 SummaryFieldsModifier and TypeFieldDescriptionprotected WriterThe underlying character-output stream of thisPrintWriter.
- 
Constructor SummaryConstructorsConstructorDescriptionPrintWriter(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 SummaryModifier 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.booleanFlushes the stream if it's not closed and checks its error state.protected voidClears the error state of this stream.voidclose()Closes the stream and releases any system resources associated with it.voidflush()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.voidprint(boolean b) Prints a boolean value.voidprint(char c) Prints a character.voidprint(char[] s) Prints an array of characters.voidprint(double d) Prints a double-precision floating-point number.voidprint(float f) Prints a floating-point number.voidprint(int i) Prints an integer.voidprint(long l) Prints a long integer.voidPrints an object.voidPrints 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.voidprintln()Terminates the current line by writing the line separator string.voidprintln(boolean x) Prints a boolean value and then terminates the line.voidprintln(char x) Prints a character and then terminates the line.voidprintln(char[] x) Prints an array of characters and then terminates the line.voidprintln(double x) Prints a double-precision floating-point number and then terminates the line.voidprintln(float x) Prints a floating-point number and then terminates the line.voidprintln(int x) Prints an integer and then terminates the line.voidprintln(long x) Prints a long integer and then terminates the line.voidPrints an Object and then terminates the line.voidPrints a String and then terminates the line.protected voidsetError()Sets the error state of the stream totrue.voidwrite(char[] buf) Writes an array of characters.voidwrite(char[] buf, int off, int len) Writes A Portion of an array of characters.voidwrite(int c) Writes a single character.voidWrites a string.voidWrites a portion of a string.Methods declared in class java.io.WriternullWriter
- 
Field Details- 
out
 
- 
- 
Constructor Details- 
PrintWriterCreates a new PrintWriter, without automatic line flushing.- Parameters:
- out- A character-output stream
 
- 
PrintWriterCreates a new PrintWriter.- Parameters:
- out- A character-output stream
- autoFlush- A boolean; if true, the- println,- printf, or- formatmethods will flush the output buffer
 
- 
PrintWriterCreates 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 charset, or whereoutis aPrintStream, the charset used by the print stream.- Parameters:
- out- An output stream
- See Also:
 
- 
PrintWriterCreates a new PrintWriter from an existing OutputStream. This convenience constructor creates the necessary intermediate OutputStreamWriter, which will convert characters into bytes using the default charset, or whereoutis aPrintStream, the charset used by the print stream.- Parameters:
- out- An output stream
- autoFlush- A boolean; if true, the- println,- printf, or- formatmethods will flush the output buffer
- See Also:
 
- 
PrintWriterCreates 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, the- println,- printf, or- formatmethods will flush the output buffer
- charset- A charset
- Since:
- 10
 
- 
PrintWriterCreates 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 file
- Since:
- 1.5
- See Also:
 
- 
PrintWriterpublic 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 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 file
- UnsupportedEncodingException- If the named charset is not supported
- Since:
- 1.5
 
- 
PrintWriterCreates 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 file
- Since:
- 10
 
- 
PrintWriterCreates 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 file
- Since:
- 1.5
- See Also:
 
- 
PrintWriterpublic 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 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 file
- UnsupportedEncodingException- If the named charset is not supported
- Since:
- 1.5
 
- 
PrintWriterCreates 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 file
- Since:
- 10
 
 
- 
- 
Method Details- 
flush
- 
close
- 
checkErrorpublic boolean checkError()Flushes the stream if it's not closed and checks its error state.- Returns:
- trueif and only if this stream has encountered an- IOException, or the- setErrormethod has been invoked
 
- 
setErrorprotected void setError()Sets the error state of the stream totrue.This method will cause subsequent invocations of checkError()to returntrueuntilclearError()is invoked.
- 
clearErrorprotected void clearError()Clears the error state of this stream.This method will cause subsequent invocations of checkError()to returnfalseuntil another write operation fails and invokessetError().- Since:
- 1.6
 
- 
write
- 
writepublic void write(char[] buf, int off, int len) Writes A Portion of an array of characters.- Specified by:
- writein class- Writer
- 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 the- offand- lenparameters cause the corresponding method of the underlying- Writerto throw an- IndexOutOfBoundsException
 
- 
write
- 
writeWrites a portion of a string.- Overrides:
- writein class- Writer
- Parameters:
- s- A String
- off- Offset from which to start writing characters
- len- Number of characters to write
- Throws:
- IndexOutOfBoundsException- If the values of the- offand- lenparameters cause the corresponding method of the underlying- Writerto throw an- IndexOutOfBoundsException
 
- 
write
- 
printpublic void print(boolean b) Prints a boolean value. The string produced byString.valueOf(boolean)is translated into bytes according to the default charset, and these bytes are written in exactly the manner of thewrite(int)method.- Parameters:
- b- The- booleanto be printed
- See Also:
 
- 
printpublic void print(char c) Prints a character. The character is translated into one or more bytes according to the default charset, and these bytes are written in exactly the manner of thewrite(int)method.- Parameters:
- c- The- charto be printed
- See Also:
 
- 
printpublic void print(int i) Prints an integer. The string produced byString.valueOf(int)is translated into bytes according to the default charset, and these bytes are written in exactly the manner of thewrite(int)method.- Parameters:
- i- The- intto be printed
- See Also:
 
- 
printpublic void print(long l) Prints a long integer. The string produced byString.valueOf(long)is translated into bytes according to the default charset, and these bytes are written in exactly the manner of thewrite(int)method.- Parameters:
- l- The- longto be printed
- See Also:
 
- 
printpublic void print(float f) Prints a floating-point number. The string produced byString.valueOf(float)is translated into bytes according to the default charset, and these bytes are written in exactly the manner of thewrite(int)method.- Parameters:
- f- The- floatto be printed
- See Also:
 
- 
printpublic void print(double d) Prints a double-precision floating-point number. The string produced byString.valueOf(double)is translated into bytes according to the default charset, and these bytes are written in exactly the manner of thewrite(int)method.- Parameters:
- d- The- doubleto be printed
- See Also:
 
- 
printpublic void print(char[] s) Prints an array of characters. The characters are converted into bytes according to the default charset, and these bytes are written in exactly the manner of thewrite(int)method.- Parameters:
- s- The array of chars to be printed
- Throws:
- NullPointerException- If- sis- null
- See Also:
 
- 
printPrints a string. If the argument isnullthen the string"null"is printed. Otherwise, the string's characters are converted into bytes according to the default charset, and these bytes are written in exactly the manner of thewrite(int)method.- Parameters:
- s- The- Stringto be printed
- See Also:
 
- 
printPrints an object. The string produced by theString.valueOf(Object)method is translated into bytes according to the default charset, and these bytes are written in exactly the manner of thewrite(int)method.- Parameters:
- obj- The- Objectto be printed
- See Also:
 
- 
printlnpublic 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').
- 
printlnpublic 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- the- booleanvalue to be printed
 
- 
printlnpublic void println(char x) Prints a character and then terminates the line. This method behaves as though it invokesprint(char)and thenprintln().- Parameters:
- x- the- charvalue to be printed
 
- 
printlnpublic void println(int x) Prints an integer and then terminates the line. This method behaves as though it invokesprint(int)and thenprintln().- Parameters:
- x- the- intvalue to be printed
 
- 
printlnpublic 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- the- longvalue to be printed
 
- 
printlnpublic 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- the- floatvalue to be printed
 
- 
printlnpublic 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- the- doublevalue to be printed
 
- 
printlnpublic 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 of- charvalues to be printed
 
- 
printlnPrints a String and then terminates the line. This method behaves as though it invokesprint(String)and thenprintln().- Parameters:
- x- the- Stringvalue to be printed
 
- 
printlnPrints 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- The- Objectto be printed.
 
- 
printfA 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 a- nullargument 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 the- formatis- null
- Since:
- 1.5
 
- 
printfA 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. If- lis- nullthen 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 a- nullargument 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 the- formatis- null
- Since:
- 1.5
 
- 
formatWrites 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 a- nullargument 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 the- formatis- null
- Since:
- 1.5
 
- 
formatWrites 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- lis- nullthen 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 a- nullargument 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 the- formatis- null
- Since:
- 1.5
 
- 
appendAppends the specified character sequence to this writer.An invocation of this method of the form out.append(csq)whencsqis notnull, behaves in exactly the same way as the invocationout.write(csq.toString())Depending on the specification of toStringfor the character sequencecsq, the entire sequence may not be appended. For instance, invoking thetoStringmethod of a character buffer will return a subsequence whose content depends upon the buffer's position and limit.- Specified by:
- appendin interface- Appendable
- Overrides:
- appendin class- Writer
- Parameters:
- csq- The character sequence to append. If- csqis- null, then the four characters- "null"are appended to this writer.
- Returns:
- This writer
- Since:
- 1.5
 
- 
appendAppends a subsequence of the specified character sequence to this writer.An invocation of this method of the form out.append(csq, start, end)whencsqis notnull, behaves in exactly the same way as the invocationout.write(csq.subSequence(start, end).toString())- Specified by:
- appendin interface- Appendable
- Overrides:
- appendin class- Writer
- Parameters:
- csq- The character sequence from which a subsequence will be appended. If- csqis- null, then characters will be appended as if- csqcontained 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- If- startor- endare negative,- startis greater than- end, or- endis greater than- csq.length()
- Since:
- 1.5
 
- 
appendAppends 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:
- appendin interface- Appendable
- Overrides:
- appendin class- Writer
- Parameters:
- c- The 16-bit character to append
- Returns:
- This writer
- Since:
- 1.5
 
 
-