VirtualMachineDescriptor (Java SE 9 & JDK 9 )
Keywords: com.sun.tools.attach.VirtualMachineDescriptor class

Module jdk.attach
Package com.sun.tools.attach

## Class VirtualMachineDescriptor

- java.lang.Object
- - com.sun.tools.attach.VirtualMachineDescriptor

-     public class VirtualMachineDescriptor
      extends Object

  Describes a Java virtual machine.

  A `VirtualMachineDescriptor` is a container class used to describe a Java virtual machine. It encapsulates an identifier that identifies a target virtual machine, and a reference to the `AttachProvider` that should be used when attempting to attach to the virtual machine. The identifier is implementation-dependent but is typically the process identifier (or pid) environments where each Java virtual machine runs in its own operating system process.

  A `VirtualMachineDescriptor` also has a `displayName`. The display name is typically a human readable string that a tool might display to a user. For example, a tool that shows a list of Java virtual machines running on a system might use the display name rather than the identifier. A `VirtualMachineDescriptor` may be created without a display name. In that case the identifier is used as the display name.

  `VirtualMachineDescriptor` instances are typically created by invoking the `VirtualMachine.list()` method. This returns the complete list of descriptors to describe the Java virtual machines known to all installed `attach providers`.

  Since:
    1.6

- - ### Constructor Summary

    Constructors
    Constructor | Description
    --- | ---
    `VirtualMachineDescriptor​(AttachProvider provider, String id)` | Creates a virtual machine descriptor from the given components.
    `VirtualMachineDescriptor​(AttachProvider provider, String id, String displayName)` | Creates a virtual machine descriptor from the given components.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `String` | `displayName​()` | Return the display name component of this descriptor.
    `boolean` | `equals​(Object ob)` | Tests this VirtualMachineDescriptor for equality with another object.
    `int` | `hashCode​()` | Returns a hash-code value for this VirtualMachineDescriptor.
    `String` | `id​()` | Return the identifier component of this descriptor.
    `AttachProvider` | `provider​()` | Return the `AttachProvider` that this descriptor references.
    `String` | `toString​()` | Returns the string representation of the `VirtualMachineDescriptor`.

    - ### Methods inherited from class java.lang.Object

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

- - ### Constructor Detail

    - #### VirtualMachineDescriptor

          public VirtualMachineDescriptor​(AttachProvider provider,
                                          String id,
                                          String displayName)

      Creates a virtual machine descriptor from the given components.
      Parameters:
        `provider` - The AttachProvider to attach to the Java virtual machine.
        `id` - The virtual machine identifier.
        `displayName` - The display name.
      Throws:
        `NullPointerException` - If any of the arguments are `null`

    - #### VirtualMachineDescriptor

          public VirtualMachineDescriptor​(AttachProvider provider,
                                          String id)

      Creates a virtual machine descriptor from the given components.

      This convenience constructor works as if by invoking the three-argument constructor as follows:

      > `new `VirtualMachineDescriptor`(provider, id, id);`

      That is, it creates a virtual machine descriptor such that the display name is the same as the virtual machine identifier.

      Parameters:
        `provider` - The AttachProvider to attach to the Java virtual machine.
        `id` - The virtual machine identifier.
      Throws:
        `NullPointerException` - If `provider` or `id` is `null`.

  - ### Method Detail

    - #### provider

          public AttachProvider provider​()

      Return the `AttachProvider` that this descriptor references.
      Returns:
        The `AttachProvider` that this descriptor references.

    - #### id

          public String id​()

      Return the identifier component of this descriptor.
      Returns:
        The identifier component of this descriptor.

    - #### displayName

          public String displayName​()

      Return the display name component of this descriptor.
      Returns:
        The display name component of this descriptor.

    - #### hashCode

          public int hashCode​()

      Returns a hash-code value for this VirtualMachineDescriptor. The hash code is based upon the descriptor's components, and satifies the general contract of the `Object.hashCode` method.
      Overrides:
        `hashCode` in class `Object`
      Returns:
        A hash-code value for this descriptor.
      See Also:
        `Object.equals(java.lang.Object)`, `System.identityHashCode(java.lang.Object)`

    - #### equals

          public boolean equals​(Object ob)

      Tests this VirtualMachineDescriptor for equality with another object.

      If the given object is not a VirtualMachineDescriptor then this method returns `false`. For two VirtualMachineDescriptors to be considered equal requires that they both reference the same provider, and their `identifiers` are equal.

      This method satisfies the general contract of the `Object.equals` method.

      Overrides:
        `equals` in class `Object`
      Parameters:
        `ob` - The object to which this object is to be compared
      Returns:
        `true` if, and only if, the given object is a VirtualMachineDescriptor that is equal to this VirtualMachineDescriptor.
      See Also:
        `Object.hashCode()`, `HashMap`

    - #### toString

          public String toString​()

      Returns the string representation of the `VirtualMachineDescriptor`.
      Overrides:
        `toString` in class `Object`
      Returns:
        a string representation of the object.