# 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

  Fields
  Modifier and Type
  Field
  Description
  `protected Writer`
  `out`
  The underlying character-output stream of this `PrintWriter`.

  ### Fields declared in class Writer

  `lock`
  Modifier and Type
  Field
  Description
  `protected Object`
  `lock`
  The object used to synchronize operations on this stream.

- ## Constructor Summary

  Constructors
  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()`
  Sets the error state of the stream to `true`.
  `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 Writer

  `nullWriter`
  Modifier and Type
  Method
  Description
  `static Writer`
  `nullWriter()`
  Returns a new `Writer` which discards all characters.

  ### Methods declared in class Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`
  Modifier and Type
  Method
  Description
  `protected Object`
  `clone()`
  Creates and returns a copy of this object.
  `boolean`
  `equals(Object obj)`
  Indicates whether some other object is "equal to" this one.
  `protected void`
  `finalize()`
  Deprecated, for removal: This API element is subject to removal in a future version.
  Finalization is deprecated and subject to removal in a future release.
  `final Class<?>`
  `getClass()`
  Returns the runtime class of this `Object`.
  `int`
  `hashCode()`
  Returns a hash code value for this object.
  `final void`
  `notify()`
  Wakes up a single thread that is waiting on this object's monitor.
  `final void`
  `notifyAll()`
  Wakes up all threads that are waiting on this object's monitor.
  `String`
  `toString()`
  Returns a string representation of the object.
  `final void`
  `wait()`
  Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
  `final void`
  `wait(long timeoutMillis)`
  Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
  `final void`
  `wait(long timeoutMillis, int nanos)`
  Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

- ## Field Details

  - ### out

    protected Writer out
    The underlying character-output stream of this `PrintWriter`.
    Since:
      1.2

- ## Constructor Details

  - ### 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, the `println`, `printf`, or `format` 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 charset, or where `out` is a `PrintStream`, the charset used by the print stream.
    Parameters:
      `out` - An output stream
    See Also:
      - `OutputStreamWriter(OutputStream)`
      - `Charset.defaultCharset()`

  - ### 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 charset, or where `out` is a `PrintStream`, the charset used by the print stream.
    Parameters:
      `out` - An output stream
      `autoFlush` - A boolean; if true, the `println`, `printf`, or `format` methods will flush the output buffer
    See Also:
      - `OutputStreamWriter(OutputStream)`
      - `Charset.defaultCharset()`

  - ### 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, the `println`, `printf`, or `format` 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
    Since:
      1.5
    See Also:
      - `Charset.defaultCharset()`

  - ### 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
      `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
    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
    Since:
      1.5
    See Also:
      - `Charset.defaultCharset()`

  - ### 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
      `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
    Since:
      10

- ## Method Details

  - ### flush

    public void flush()
    Flushes the stream.
    Specified by:
      `flush` in interface `Flushable`
    Specified by:
      `flush` in class `Writer`
    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 interface `AutoCloseable`
    Specified by:
      `close` in interface `Closeable`
    Specified by:
      `close` in class `Writer`
    See Also:
      - `checkError()`

  - ### checkError

    public boolean checkError()
    Flushes the stream if it's not closed and checks its error state.
    Returns:
      `true` if and only if this stream has encountered an `IOException`, or the `setError` method has been invoked

  - ### setError

    protected void setError()
    Sets the error state of the stream to `true`.

    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.
    Overrides:
      `write` in class `Writer`
    Parameters:
      `c` - int specifying a character to be written.

  - ### write

    public void write(char[] buf, int off, int len)
    Writes A Portion of an array of characters.
    Specified by:
      `write` in 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 `off` and `len` parameters cause the corresponding method of the underlying `Writer` to throw an `IndexOutOfBoundsException`

  - ### write

    public void write(char[] buf)
    Writes an array of characters. This method cannot be inherited from the Writer class because it must suppress I/O exceptions.
    Overrides:
      `write` in class `Writer`
    Parameters:
      `buf` - Array of characters to be written

  - ### write

    public void write(String s, int off, int len)
    Writes a portion of a string.
    Overrides:
      `write` in 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 `off` and `len` parameters cause the corresponding method of the underlying `Writer` to throw an `IndexOutOfBoundsException`

  - ### write

    public void write(String s)
    Writes a string. This method cannot be inherited from the Writer class because it must suppress I/O exceptions.
    Overrides:
      `write` in class `Writer`
    Parameters:
      `s` - String to be written

  - ### print

    public void print(boolean b)
    Prints a boolean value. The string produced by `String.valueOf(boolean)` is translated into bytes according to the default charset, and these bytes are written in exactly the manner of the `write(int)` method.
    Parameters:
      `b` - The `boolean` to be printed
    See Also:
      - `Charset.defaultCharset()`

  - ### print

    public 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 the `write(int)` method.
    Parameters:
      `c` - The `char` to be printed
    See Also:
      - `Charset.defaultCharset()`

  - ### print

    public void print(int i)
    Prints an integer. The string produced by `String.valueOf(int)` is translated into bytes according to the default charset, and these bytes are written in exactly the manner of the `write(int)` method.
    Parameters:
      `i` - The `int` to be printed
    See Also:
      - `Integer.toString(int)`
      - `Charset.defaultCharset()`

  - ### print

    public void print(long l)
    Prints a long integer. The string produced by `String.valueOf(long)` is translated into bytes according to the default charset, and these bytes are written in exactly the manner of the `write(int)` method.
    Parameters:
      `l` - The `long` to be printed
    See Also:
      - `Long.toString(long)`
      - `Charset.defaultCharset()`

  - ### print

    public void print(float f)
    Prints a floating-point number. The string produced by `String.valueOf(float)` is translated into bytes according to the default charset, and these bytes are written in exactly the manner of the `write(int)` method.
    Parameters:
      `f` - The `float` to be printed
    See Also:
      - `Float.toString(float)`
      - `Charset.defaultCharset()`

  - ### print

    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 default charset, and these bytes are written in exactly the manner of the `write(int)` method.
    Parameters:
      `d` - The `double` to be printed
    See Also:
      - `Double.toString(double)`
      - `Charset.defaultCharset()`

  - ### print

    public 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 the `write(int)` method.
    Parameters:
      `s` - The array of chars to be printed
    Throws:
      `NullPointerException` - If `s` is `null`
    See Also:
      - `Charset.defaultCharset()`

  - ### print

    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 default charset, and these bytes are written in exactly the manner of the `write(int)` method.
    Parameters:
      `s` - The `String` to be printed
    See Also:
      - `Charset.defaultCharset()`

  - ### print

    public void print(Object obj)
    Prints an object. The string produced by the `String.valueOf(Object)` method is translated into bytes according to the default charset, and these bytes are written in exactly the manner of the `write(int)` method.
    Parameters:
      `obj` - The `Object` to be printed
    See Also:
      - `Object.toString()`
      - `Charset.defaultCharset()`

  - ### println

    public void println()
    Terminates the current line by writing the line separator string. The line separator is `System.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 invokes `print(boolean)` and then `println()`.
    Parameters:
      `x` - the `boolean` 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` - the `char` 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` - the `int` 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` - the `long` 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` - the `float` value to be printed

  - ### println

    public void println(double x)
    Prints a double-precision floating-point number and then terminates the line. This method behaves as though it invokes `print(double)` and then `println()`.
    Parameters:
      `x` - the `double` 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 of `char` 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` - the `String` 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` - The `Object` 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 a `null` 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 the `format` is `null`
    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. 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.
    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 `format` is `null`
    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 a `null` 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 the `format` is `null`
    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. 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.
    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 `format` is `null`
    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)` when `csq` is not `null`, 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 interface `Appendable`
    Overrides:
      `append` in class `Writer`
    Parameters:
      `csq` - The character sequence to append. If `csq` is `null`, 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 interface `Appendable`
    Overrides:
      `append` in class `Writer`
    Parameters:
      `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 subsequence
      `end` - The index of the character following the last character in the subsequence
    Returns:
      This writer
    Throws:
      `IndexOutOfBoundsException` - If `start` or `end` are negative, `start` is greater than `end`, or `end` is greater than `csq.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 interface `Appendable`
    Overrides:
      `append` in class `Writer`
    Parameters:
      `c` - The 16-bit character to append
    Returns:
      This writer
    Since:
      1.5