A PrintStream
adds functionality to another output stream,
namely the ability to print representations of various data values
conveniently. Two other features are provided as well. Unlike other output
streams, a PrintStream
never throws an
IOException
; instead, exceptional situations merely set an
internal flag that can be tested via the checkError
method.
Optionally, a PrintStream
can be created so as to flush
automatically; this means that the flush
method is
automatically invoked after a byte array is written, one of the
println
methods is invoked, or a newline character or byte
('\n'
) is written.
All characters printed by a PrintStream
are converted into
bytes using the platform's default character encoding. The
class should be used in situations that require writing
characters rather than bytes.PrintWriter
Inherited Field Summary
Public Constructor Summary
PrintStream(String fileName)
Creates a new print stream, without automatic line flushing, with the
specified file name.
|
|
PrintStream(String fileName, String csn)
Creates a new print stream, without automatic line flushing, with the
specified file name and charset.
|
|
PrintStream(File file)
Creates a new print stream, without automatic line flushing, with the
specified file.
|
|
PrintStream(File file, String csn)
Creates a new print stream, without automatic line flushing, with the
specified file and charset.
|
Public Method Summary
PrintStream |
append(char c)
Appends the specified character to this output stream.
|
PrintStream |
append(CharSequence csq, int start, int end)
Appends a subsequence of the specified character sequence to this output
stream.
|
PrintStream | |
boolean |
checkError()
Flushes the stream and checks its error state.
|
void |
close()
Closes the stream.
|
void |
flush()
Flushes the stream.
|
PrintStream | |
PrintStream | |
void |
print(int i)
Prints an integer.
|
void |
print(double d)
Prints a double-precision floating-point number.
|
void |
print(boolean b)
Prints a boolean value.
|
void |
print(char c)
Prints a character.
|
void |
print(long l)
Prints a long integer.
|
void |
print(float f)
Prints a floating-point number.
|
void | |
void | |
void |
print(char[] s)
Prints an array of characters.
|
PrintStream | |
PrintStream | |
void | |
void |
println(char x)
Prints a character and then terminate the line.
|
void |
println(boolean x)
Prints a boolean and then terminate the line.
|
void |
println(long x)
Prints a long and then terminate the line.
|
void |
println()
Terminates the current line by writing the line separator string.
|
void |
println(int x)
Prints an integer and then terminate the line.
|
void | |
void |
println(char[] x)
Prints an array of characters and then terminate the line.
|
void |
println(float x)
Prints a float and then terminate the line.
|
void |
println(double x)
Prints a double and then terminate the line.
|
void |
write(byte[] buf, int off, int len)
Writes
len bytes from the specified byte array starting at
offset off to this stream. |
void |
write(int b)
Writes the specified byte to this stream.
|
Protected Method Summary
void |
clearError()
Clears the internal error state of this stream.
|
void |
setError()
Sets the error state of the stream to
true . |
Inherited Method Summary
Public Constructors
public PrintStream (OutputStream out)
Creates a new print stream. This stream will not flush automatically.
Parameters
out | The output stream to which values and objects will be printed |
---|
public PrintStream (OutputStream out, boolean autoFlush)
Creates a new print stream.
Parameters
out | The output stream to which values and objects will be printed |
---|---|
autoFlush | A boolean; if true, the output buffer will be flushed
whenever a byte array is written, one of the
println methods is invoked, or a newline
character or byte ('\n' ) is written |
public PrintStream (OutputStream out, boolean autoFlush, String encoding)
Creates a new print stream.
Parameters
out | The output stream to which values and objects will be printed |
---|---|
autoFlush | A boolean; if true, the output buffer will be flushed
whenever a byte array is written, one of the
println methods is invoked, or a newline
character or byte ('\n' ) is written |
encoding | The name of a supported character encoding |
Throws
UnsupportedEncodingException | If the named encoding is not supported |
---|
public PrintStream (String fileName)
Creates a new print stream, without automatic line flushing, with the
specified file name. This convenience constructor creates
the necessary intermediate OutputStreamWriter
, which will encode characters using the
{@linkplain java.nio.charset.Charset#defaultCharset() default charset}
for this instance of the Java virtual machine.
Parameters
fileName | The name of the file to use as the destination of this print stream. 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. |
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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 and checkWrite(fileName) denies write
access to the file |
public PrintStream (String fileName, String csn)
Creates a new print stream, 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 print stream. 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 {@linkplain java.nio.charset.Charset 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 and checkWrite(fileName) denies write
access to the file |
UnsupportedEncodingException | If the named charset is not supported |
public PrintStream (File file)
Creates a new print stream, without automatic line flushing, with the
specified file. This convenience constructor creates the necessary
intermediate OutputStreamWriter
,
which will encode characters using the {@linkplain java.nio.charset.Charset#defaultCharset() default charset} for this
instance of the Java virtual machine.
Parameters
file | The file to use as the destination of this print stream. 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. |
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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 and checkWrite(file.getPath())
denies write access to the file |
public PrintStream (File file, String csn)
Creates a new print stream, 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 print stream. 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 {@linkplain java.nio.charset.Charset 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 and checkWrite(file.getPath())
denies write access to the file |
UnsupportedEncodingException | If the named charset is not supported |
Public Methods
public PrintStream append (char c)
Appends the specified character to this output stream.
An invocation of this method of the form out.append(c) behaves in exactly the same way as the invocation
out.print(c)
Parameters
c | The 16-bit character to append |
---|
Returns
- This output stream
public PrintStream append (CharSequence csq, int start, int end)
Appends a subsequence of the specified character sequence to this output stream.
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.print(csq.subSequence(start, end).toString())
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 output stream
Throws
IndexOutOfBoundsException | If start or end are negative, start is greater than end, or end is greater than csq.length() |
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public PrintStream append (CharSequence csq)
Appends the specified character sequence to this output stream.
An invocation of this method of the form out.append(csq) behaves in exactly the same way as the invocation
out.print(csq.toString())
Depending on the specification of toString for the character sequence csq, the entire sequence may not be appended. For instance, invoking then toString method of a character buffer will return a subsequence whose content depends upon the buffer's position and limit.
Parameters
csq | The character sequence to append. If csq is null, then the four characters "null" are appended to this output stream. |
---|
Returns
- This output stream
public boolean checkError ()
Flushes the stream and checks its error state. The internal error state
is set to true
when the underlying output stream throws an
IOException
other than InterruptedIOException
,
and when the setError
method is invoked. If an operation
on the underlying output stream throws an
InterruptedIOException
, then the PrintStream
converts the exception back into an interrupt by doing:
Thread.currentThread().interrupt();
Returns
true
if and only if this stream has encountered anIOException
other thanInterruptedIOException
, or thesetError
method has been invoked
public void close ()
Closes the stream. This is done by flushing the stream and then closing the underlying output stream.
See Also
public void flush ()
Flushes the stream. This is done by writing any buffered output bytes to the underlying output stream and then flushing that stream.
See Also
public PrintStream format (Locale l, String format, Object... args)
Writes a formatted string to this output stream using the specified format string and arguments.
Parameters
l | The {@linkplain java.util.Locale 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 output stream
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 |
public PrintStream format (String format, Object... args)
Writes a formatted string to this output stream using the specified format string and arguments.
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 output stream
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 |
public void print (int i)
Prints an integer. The string produced by
is translated into bytes
according to the platform's default character encoding, and these bytes
are written in exactly the manner of the
String.valueOf(int)
method.write(int)
Parameters
i | The int to be printed |
---|
See Also
public void print (double d)
Prints a double-precision floating-point number. The string produced by
is translated into
bytes according to the platform's default character encoding, and these
bytes are written in exactly the manner of the String.valueOf(double)
method.write(int)
Parameters
d | The double to be printed |
---|
See Also
public void print (boolean b)
Prints a boolean value. The string produced by
is translated into bytes
according to the platform's default character encoding, and these bytes
are written in exactly the manner of the
String.valueOf(boolean)
method.write(int)
Parameters
b | The boolean to be printed
|
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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
method.write(int)
Parameters
c | The char to be printed
|
---|
public void print (long l)
Prints a long integer. The string produced by
is translated into bytes
according to the platform's default character encoding, and these bytes
are written in exactly the manner of the
String.valueOf(long)
method.write(int)
Parameters
l | The long to be printed |
---|
See Also
public void print (float f)
Prints a floating-point number. The string produced by
is translated into bytes
according to the platform's default character encoding, and these bytes
are written in exactly the manner of the
String.valueOf(float)
method.write(int)
Parameters
f | The float to be printed |
---|
See Also
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
method.write(int)
Parameters
s | The String to be printed
|
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public void print (Object obj)
Prints an object. The string produced by the
method is translated into bytes
according to the platform's default character encoding, and these bytes
are written in exactly the manner of the
String.valueOf(Object)
method.write(int)
Parameters
obj | The Object to be printed |
---|
See Also
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
method.write(int)
Parameters
s | The array of chars to be printed |
---|
Throws
NullPointerException | If s is null
|
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public PrintStream printf (String format, Object... args)
A convenience method to write a formatted string to this output stream using the specified format string and arguments.
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 output stream
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 |
public PrintStream printf (Locale l, String format, Object... args)
A convenience method to write a formatted string to this output stream using the specified format string and arguments.
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 {@linkplain java.util.Locale 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 output stream
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 |
public void println (Object x)
Prints an Object and then terminate the line. This method calls
at first String.valueOf(x) to get the printed object's string value,
then behaves as
though it invokes
and then
print(String)
.println()
Parameters
x | The Object to be printed.
|
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public void println (char x)
Prints a character and then terminate the line. This method behaves as
though it invokes
and then
print(char)
.println()
Parameters
x | The char to be printed.
|
---|
public void println (boolean x)
Prints a boolean and then terminate the line. This method behaves as
though it invokes
and then
print(boolean)
.println()
Parameters
x | The boolean to be printed
|
---|
public void println (long x)
Prints a long and then terminate the line. This method behaves as
though it invokes
and then
print(long)
.println()
Parameters
x | a The long to be printed.
|
---|
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 (int x)
Prints an integer and then terminate the line. This method behaves as
though it invokes
and then
print(int)
.println()
Parameters
x | The int to be printed.
|
---|
public void println (String x)
Prints a String and then terminate the line. This method behaves as
though it invokes
and then
print(String)
.println()
Parameters
x | The String to be printed.
|
---|
public void println (char[] x)
Prints an array of characters and then terminate the line. This method
behaves as though it invokes
and
then print(char[])
.println()
Parameters
x | an array of chars to print. |
---|
public void println (float x)
Prints a float and then terminate the line. This method behaves as
though it invokes
and then
print(float)
.println()
Parameters
x | The float to be printed.
|
---|
public void println (double x)
Prints a double and then terminate the line. This method behaves as
though it invokes
and then
print(double)
.println()
Parameters
x | The double to be printed.
|
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public void write (byte[] buf, int off, int len)
Writes len
bytes from the specified byte array starting at
offset off
to this stream. If automatic flushing is
enabled then the flush
method will be invoked.
Note that the bytes will be written as given; to write characters
that will be translated according to the platform's default character
encoding, use the print(char)
or println(char)
methods.
Parameters
buf | A byte array |
---|---|
off | Offset from which to start taking bytes |
len | Number of bytes to write |
public void write (int b)
Writes the specified byte to this stream. If the byte is a newline and
automatic flushing is enabled then the flush
method will be
invoked.
Note that the byte is written as given; to write a character that
will be translated according to the platform's default character
encoding, use the print(char)
or println(char)
methods.
Parameters
b | The byte to be written |
---|
See Also
Protected Methods
protected void clearError ()
Clears the internal error state of this stream.
This method will cause subsequent invocations of checkError()
to return false until another write
operation fails and invokes 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.