# Class ProcessBuilder.Redirect

java.lang.Object
java.lang.ProcessBuilder.Redirect

Enclosing class:
  `ProcessBuilder`

public abstract static class ProcessBuilder.Redirect extends Object
Represents a source of subprocess input or a destination of subprocess output. Each `Redirect` instance is one of the following:

- the special value `Redirect.PIPE`
- the special value `Redirect.INHERIT`
- the special value `Redirect.DISCARD`
- a redirection to read from a file, created by an invocation of `Redirect.from(File)`
- a redirection to write to a file, created by an invocation of `Redirect.to(File)`
- a redirection to append to a file, created by an invocation of `Redirect.appendTo(File)`

Each of the above categories has an associated unique `Type`.

Since:
  1.7

- ## Nested Class Summary

  Nested Classes
  Modifier and Type
  Class
  Description
  `static enum`
  `ProcessBuilder.Redirect.Type`
  The type of a `ProcessBuilder.Redirect`.

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `static final ProcessBuilder.Redirect`
  `DISCARD`
  Indicates that subprocess output will be discarded.
  `static final ProcessBuilder.Redirect`
  `INHERIT`
  Indicates that subprocess I/O source or destination will be the same as those of the current process.
  `static final ProcessBuilder.Redirect`
  `PIPE`
  Indicates that subprocess I/O will be connected to the current Java process over a pipe.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `static ProcessBuilder.Redirect`
  `appendTo(File file)`
  Returns a redirect to append to the specified file.
  `boolean`
  `equals(Object obj)`
  Compares the specified object with this `Redirect` for equality.
  `File`
  `file()`
  Returns the `File` source or destination associated with this redirect, or `null` if there is no such file.
  `static ProcessBuilder.Redirect`
  `from(File file)`
  Returns a redirect to read from the specified file.
  `int`
  `hashCode()`
  Returns a hash code value for this `Redirect`.
  `static ProcessBuilder.Redirect`
  `to(File file)`
  Returns a redirect to write to the specified file.
  `abstract ProcessBuilder.Redirect.Type`
  `type()`
  Returns the type of this `Redirect`.

  ### Methods declared in class Object

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

- ## Field Details

  - ### PIPE

    public static final ProcessBuilder.Redirect PIPE
    Indicates that subprocess I/O will be connected to the current Java process over a pipe. This is the default handling of subprocess standard I/O.

    It will always be true that

            Redirect.PIPE.file() == null &&
            Redirect.PIPE.type() == Redirect.Type.PIPE

  - ### INHERIT

    public static final ProcessBuilder.Redirect INHERIT
    Indicates that subprocess I/O source or destination will be the same as those of the current process. This is the normal behavior of most operating system command interpreters (shells).

    It will always be true that

            Redirect.INHERIT.file() == null &&
            Redirect.INHERIT.type() == Redirect.Type.INHERIT

  - ### DISCARD

    public static final ProcessBuilder.Redirect DISCARD
    Indicates that subprocess output will be discarded. A typical implementation discards the output by writing to an operating system specific "null file".

    It will always be true that

            Redirect.DISCARD.file() != null && // is the filename appropriate for the operating system
            Redirect.DISCARD.type() == Redirect.Type.WRITE;

    Since:
      9

- ## Method Details

  - ### type

    public abstract ProcessBuilder.Redirect.Type type()
    Returns the type of this `Redirect`.
    Returns:
      the type of this `Redirect`

  - ### file

    public File file()
    Returns the `File` source or destination associated with this redirect, or `null` if there is no such file.
    Returns:
      the file associated with this redirect, or `null` if there is no such file

  - ### from

    public static ProcessBuilder.Redirect from(File file)
    Returns a redirect to read from the specified file.

    It will always be true that

            Redirect.from(file).file() == file &&
            Redirect.from(file).type() == Redirect.Type.READ

    Parameters:
      `file` - The `File` for the `Redirect`.
    Returns:
      a redirect to read from the specified file

  - ### to

    public static ProcessBuilder.Redirect to(File file)
    Returns a redirect to write to the specified file. If the specified file exists when the subprocess is started, its previous contents will be discarded.

    It will always be true that

            Redirect.to(file).file() == file &&
            Redirect.to(file).type() == Redirect.Type.WRITE

    Parameters:
      `file` - The `File` for the `Redirect`.
    Returns:
      a redirect to write to the specified file

  - ### appendTo

    public static ProcessBuilder.Redirect appendTo(File file)
    Returns a redirect to append to the specified file. Each write operation first advances the position to the end of the file and then writes the requested data. Whether the advancement of the position and the writing of the data are done in a single atomic operation is system-dependent and therefore unspecified.

    It will always be true that

            Redirect.appendTo(file).file() == file &&
            Redirect.appendTo(file).type() == Redirect.Type.APPEND

    Parameters:
      `file` - The `File` for the `Redirect`.
    Returns:
      a redirect to append to the specified file

  - ### equals

    public boolean equals(Object obj)
    Compares the specified object with this `Redirect` for equality. Returns `true` if and only if the two objects are identical or both objects are `Redirect` instances of the same type associated with non-null equal `File` instances.
    Overrides:
      `equals` in class `Object`
    Parameters:
      `obj` - the reference object with which to compare.
    Returns:
      `true` if this object is the same as the obj argument; `false` otherwise.
    See Also:
      - `Object.hashCode()`
      - `HashMap`

  - ### hashCode

    public int hashCode()
    Returns a hash code value for this `Redirect`.
    Overrides:
      `hashCode` in class `Object`
    Returns:
      a hash code value for this `Redirect`
    See Also:
      - `Object.equals(java.lang.Object)`
      - `System.identityHashCode(Object)`