Module java.base
Package java.io

# Class PrintStream

java.lang.Object
java.io.OutputStream
java.io.FilterOutputStream
java.io.PrintStream

All Implemented Interfaces:
  `Closeable`, `Flushable`, `Appendable`, `AutoCloseable`

Direct Known Subclasses:
  `LogStream`

    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 given encoding or charset, or platform's default character encoding if not specified. The `PrintWriter` class should be used in situations that require writing characters rather than bytes.

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:
  1.0

## Field Summary

### Fields declared in class java.io.FilterOutputStream

`out`

## Constructor Summary

Constructors
Constructor | 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​(File file, Charset charset)` | 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​(OutputStream out, boolean autoFlush, Charset charset)` | Creates a new print stream, with the specified OutputStream, automatic line flushing and charset.
`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​(String fileName, Charset charset)` | Creates a new print stream, without automatic line flushing, with the specified file name and charset.

## Method Summary

Modifier and Type | Method | 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.
`boolean` | `checkError()` | Flushes the stream and checks its error state.
`protected void` | `clearError()` | Clears the internal error state of this stream.
`void` | `close()` | Closes the stream.
`void` | `flush()` | Flushes the stream.
`PrintStream` | `format​(String format, Object... args)` | Writes a formatted string to this output stream using the specified format string and arguments.
`PrintStream` | `format​(Locale l, String format, Object... args)` | Writes a formatted string to this output stream 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.
`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.
`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.
`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​(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​(double x)` | Prints a double and then terminate the line.
`void` | `println​(float x)` | Prints a float 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 declared in class java.io.FilterOutputStream

`write`

### Methods declared in class java.io.OutputStream

`nullOutputStream`

### Methods declared in class java.lang.Object

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

## Constructor Details

### 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(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(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​(OutputStream out, boolean autoFlush, Charset charset)
Creates a new print stream, with the specified OutputStream, automatic line flushing and charset. This convenience constructor creates the necessary intermediate `OutputStreamWriter`, which will encode characters using the provided charset.

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
  `charset` - A charset
Since:
  10

### 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​(String fileName, Charset charset) throws IOException
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.
  `charset` - A charset
Throws:
  `IOException` - if an I/O 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:
  10

### 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 present and `checkWrite(file.getPath())` denies write access to the file
  `UnsupportedEncodingException` - If the named charset is not supported
Since:
  1.5

### PrintStream

public PrintStream​(File file, Charset charset) throws IOException
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.
  `charset` - A charset
Throws:
  `IOException` - if an I/O 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:
  10

## Method Details

### 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 `AutoCloseable`
Specified by:
  `close` in interface `Closeable`
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:
  1.1

### 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

### printf

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 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`
Since:
  1.5

### format

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(Locale.Category)` with `FORMAT` category specified, 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`
Since:
  1.5

### format

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 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`
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