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().
protected Writer out
The underlying character-output stream of this PrintWriter.
public PrintWriter(Writer out)
Creates a new PrintWriter, without automatic line flushing.
out - A character-output streampublic PrintWriter(Writer out,
boolean autoFlush) Creates a new PrintWriter.
out - A character-output streamautoFlush - A boolean; if true, the println, printf, or format methods will flush the output bufferpublic 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.
out - An output streamOutputStreamWriter.OutputStreamWriter(java.io.OutputStream)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.
out - An output streamautoFlush - A boolean; if true, the println, printf, or format methods will flush the output bufferOutputStreamWriter.OutputStreamWriter(java.io.OutputStream)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.
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.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 and checkWrite(fileName) denies write access to the filepublic 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.
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
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 and checkWrite(fileName) denies write access to the fileUnsupportedEncodingException - If the named charset is not supportedpublic 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.
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.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 and checkWrite(file.getPath()) denies write access to the filepublic 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.
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
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 and checkWrite(file.getPath()) denies write access to the fileUnsupportedEncodingException - If the named charset is not supportedpublic void flush()
Flushes the stream.
flush in interface Flushable
flush in class Writer
checkError()public void close()
Closes the stream and releases any system resources associated with it. Closing a previously closed stream has no effect.
close in interface Closeable
close in interface AutoCloseable
close in class Writer
checkError()public boolean checkError()
Flushes the stream if it's not closed and checks its error state.
true if the print stream has encountered an error, either on the underlying output stream or during a format conversion.protected void setError()
Indicates that an error has occurred.
This method will cause subsequent invocations of checkError() to return true until clearError() is invoked.
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().
public void write(int c)
Writes a single character.
public void write(char[] buf,
int off,
int len) Writes A Portion of an array of characters.
write in class Writer
buf - Array of charactersoff - Offset from which to start writing characterslen - Number of characters to writepublic 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.
public void write(String s,
int off,
int len) Writes a portion of a string.
write in class Writer
s - A Stringoff - Offset from which to start writing characterslen - Number of characters to writepublic 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)write(int)
b - The boolean to be printedpublic 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)
c - The char to be printedpublic void print(int i)
Prints an integer. The string produced by String.valueOf(int)write(int)
i - The int to be printedInteger.toString(int)public void print(long l)
Prints a long integer. The string produced by String.valueOf(long)write(int)
l - The long to be printedLong.toString(long)public void print(float f)
Prints a floating-point number. The string produced by String.valueOf(float)write(int)
f - The float to be printedFloat.toString(float)public void print(double d)
Prints a double-precision floating-point number. The string produced by String.valueOf(double)write(int)
d - The double to be printedDouble.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)
s - The array of chars to be printedNullPointerException - If s is null
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)
s - The String to be printedpublic void print(Object obj)
Prints an object. The string produced by the String.valueOf(Object)write(int)
obj - The Object to be printedObject.toString()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').
public void println(boolean x)
Prints a boolean value and then terminates the line. This method behaves as though it invokes print(boolean)println()
x - the boolean value to be printedpublic void println(char x)
Prints a character and then terminates the line. This method behaves as though it invokes print(char)println()
x - the char value to be printedpublic void println(int x)
Prints an integer and then terminates the line. This method behaves as though it invokes print(int)println()
x - the int value to be printedpublic void println(long x)
Prints a long integer and then terminates the line. This method behaves as though it invokes print(long)println()
x - the long value to be printedpublic void println(float x)
Prints a floating-point number and then terminates the line. This method behaves as though it invokes print(float)println()
x - the float value to be printedpublic 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)println()
x - the double value to be printedpublic void println(char[] x)
Prints an array of characters and then terminates the line. This method behaves as though it invokes print(char[])println()
x - the array of char values to be printedpublic void println(String x)
Prints a String and then terminates the line. This method behaves as though it invokes print(String)println()
x - the String value to be printedpublic 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)println()
x - The Object to be printed.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)
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 null argument depends on the conversion.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 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)
l - The locale to apply during formatting. If l is null then no localization is applied.format - A format string as described in Format string syntax.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 null argument depends on the conversion.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 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.
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 null argument depends on the conversion.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 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.
l - The locale to apply during formatting. If l is null then no localization is applied.format - A format string as described in Format string syntax.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 null argument depends on the conversion.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 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.
append in interface Appendable
append in class Writer
csq - The character sequence to append. If csq is null, then the four characters "null" are appended to this writer.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())
append in interface Appendable
append in class Writer
csq - The character sequence from which a subsequence will be appended. If csq is null, then characters will be appended as if csq contained the four characters "null".start - The index of the first character in the subsequenceend - The index of the character following the last character in the subsequenceIndexOutOfBoundsException - If start or end are negative, start is greater than end, or end is greater than csq.length()
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)
append in interface Appendable
append in class Writer
c - The 16-bit character to append
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