java.io

Class PrintStream

java.lang.Object

java.io.OutputStream

java.io.FilterOutputStream

java.io.PrintStream

All Implemented Interfaces:

Closeable, Flushable, Appendable, AutoCloseable

public class PrintStream
extends FilterOutputStream
implements Appendable, Closeable

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 PrintWriter class should be used in situations that require writing characters rather than bytes.

Since:

JDK1.0

Author:

Frank Yellin, Mark Reinhold

Field Summary

Fields inherited from class java.io.FilterOutputStream

out

Constructor Summary

Constructors

Constructor and Description
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.
PrintStream(OutputStream out) Creates a new print stream.
PrintStream(OutputStream out, boolean autoFlush) Creates a new print stream.
PrintStream(OutputStream out, boolean autoFlush, String encoding) Creates a new print stream.
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.

Method Summary

Methods

Modifier and Type	Method and Description
PrintStream	append(char c) Appends the specified character to this output stream.
PrintStream	append(CharSequence csq) Appends the specified character sequence to this output stream.
PrintStream	append(CharSequence csq, int start, int end) Appends a subsequence of the specified character sequence to this output stream.
protected void	clearError() Clears the internal error state of this stream.
void	close() Closes the stream.
void	flush() Flushes the stream.
boolean	checkError() Flushes the stream and checks its error state.
void	print(boolean b) Prints a boolean value.
void	print(double d) Prints a double-precision floating-point number.
void	print(float f) Prints a floating-point number.
void	print(char c) Prints a character.
void	print(char[] s) Prints an array of characters.
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.
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.
void	println() Terminates the current line by writing the line separator string.
void	println(boolean x) Prints a boolean and then terminate the line.
void	println(double x) Prints a double and then terminate the line.
void	println(float x) Prints a float and then terminate the line.
void	println(char x) Prints a character and then terminate the line.
void	println(char[] x) Prints an array of characters and then terminate the line.
void	println(int x) Prints an integer and then terminate the line.
void	println(long x) Prints a long and then terminate the line.
void	println(Object x) Prints an Object and then terminate the line.
void	println(String x) Prints a String and then terminate the line.
protected void	setError() Sets the error state of the stream to true.
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.

Methods inherited from class java.io.FilterOutputStream

write

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PrintStream

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

See Also:

PrintWriter.PrintWriter(java.io.OutputStream)

PrintStream

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

See Also:

PrintWriter.PrintWriter(java.io.OutputStream, boolean)

PrintStream

public PrintStream(OutputStream out,
           boolean autoFlush,
           String encoding)
            throws UnsupportedEncodingException

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

Since:

1.4

PrintStream

public PrintStream(String fileName)
            throws FileNotFoundException

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 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.

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

Since:

1.5

PrintStream

public PrintStream(String fileName,
           String csn)
            throws FileNotFoundException,
                   UnsupportedEncodingException

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 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

Since:

1.5

PrintStream

public PrintStream(File file)
            throws FileNotFoundException

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 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.

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

Since:

1.5

PrintStream

public PrintStream(File file,
           String csn)
            throws FileNotFoundException,
                   UnsupportedEncodingException

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 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 presentand checkWrite(file.getPath()) denies write access to the file

UnsupportedEncodingException - If the named charset is not supported

Since:

1.5

Method Detail

flush

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.

Specified by:

flush in interface Flushable

Overrides:

flush in class FilterOutputStream

See Also:

OutputStream.flush()

close

public void close()

Closes the stream. This is done by flushing the stream and then closing the underlying output stream.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class FilterOutputStream

See Also:

OutputStream.close()

checkError

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();
 

or the equivalent.

Returns:

true if and only if this stream has encountered an IOException other than InterruptedIOException, 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.

Since:

JDK1.1

clearError

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().

Since:

1.6

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.

Overrides:

write in class FilterOutputStream

Parameters:

b - The byte to be written

See Also:

print(char), println(char)

write

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.

Overrides:

write in class FilterOutputStream

Parameters:

buf - A byte array

off - Offset from which to start taking bytes

len - Number of bytes to write

See Also:

FilterOutputStream.write(int)

print

public void print(boolean b)

Prints a boolean value. The string produced by String.valueOf(boolean) is translated into bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of the write(int) method.

Parameters:

b - The boolean to be printed

print

public void print(char c)

Prints a character. The character is translated into one or more bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of the write(int) method.

Parameters:

c - The char to be printed

print

public void print(int i)

Prints an integer. The string produced by String.valueOf(int) is translated into bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of the write(int) method.

Parameters:

i - The int to be printed

See Also:

Integer.toString(int)

print

public void print(long l)

Prints a long integer. The string produced by String.valueOf(long) is translated into bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of the write(int) method.

Parameters:

l - The long to be printed

See Also:

Long.toString(long)

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 platform's default character encoding, 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)

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 platform's default character encoding, 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)

print

public void print(char[] s)

Prints an array of characters. The characters are converted into bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of the write(int) method.

Parameters:

s - The array of chars to be printed

Throws:

NullPointerException - If s is null

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 platform's default character encoding, and these bytes are written in exactly the manner of the write(int) method.

Parameters:

s - The String to be printed

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 platform's default character encoding, 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()

println

public void println()

Terminates the current line by writing the line separator string. The line separator string is defined by the system property line.separator, and is not necessarily a single newline character ('\n').

println

public void println(boolean x)

Prints a boolean and then terminate the line. This method behaves as though it invokes print(boolean) and then println().

Parameters:

x - The boolean to be printed

println

public void println(char x)

Prints a character and then terminate the line. This method behaves as though it invokes print(char) and then println().

Parameters:

x - The char to be printed.

println

public void println(int x)

Prints an integer and then terminate the line. This method behaves as though it invokes print(int) and then println().

Parameters:

x - The int to be printed.

println

public void println(long x)

Prints a long and then terminate the line. This method behaves as though it invokes print(long) and then println().

Parameters:

x - a The long to be printed.

println

public void println(float x)

Prints a float and then terminate the line. This method behaves as though it invokes print(float) and then println().

Parameters:

x - The float to be printed.

println

public void println(double x)

Prints a double and then terminate the line. This method behaves as though it invokes print(double) and then println().

Parameters:

x - The double to be printed.

println

public void println(char[] x)

Prints an array of characters and then terminate the line. This method behaves as though it invokes print(char[]) and then println().

Parameters:

x - an array of chars to print.

println

public void println(String x)

Prints a String and then terminate the line. This method behaves as though it invokes print(String) and then println().

Parameters:

x - The String to be printed.

println

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 print(String) and then println().

Parameters:

x - The Object to be printed.

printf

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

Since:

1.5

append

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.

Specified by:

append in interface Appendable

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

Since:

1.5

append

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()) 

Specified by:

append in interface Appendable

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()

Since:

1.5

append

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) 

Specified by:

append in interface Appendable

Parameters:

c - The 16-bit character to append

Returns:

This output stream

Since:

1.5