Module jdk.jshell

Package jdk.jshell

Enum Snippet.Status

java.lang.Object

java.lang.Enum<Snippet.Status>

jdk.jshell.Snippet.Status

All Implemented Interfaces:

Serializable, Comparable<Snippet.Status>

Enclosing class:

Snippet

public static enum Snippet.Status
extends Enum<Snippet.Status>

Describes the current state of a Snippet. This is a dynamic property of a Snippet within the JShell state -- thus is retrieved with a query on {@code JShell}.

The Status changes as the state changes. For example, creation of another snippet with eval may resolve dependencies of this Snippet (or invalidate those dependencies), or overwrite this Snippet changing its Status.

Important properties associated with Status are: isDefined(), if it is visible to other existing and new snippets; and isActive(), if, as the JShell state changes, the snippet will update, possibly changing Status. An executable Snippet can only be executed if it is in the the VALID Status.

See Also:

JShell.status(jdk.jshell.Snippet)

Enum Constant Summary

Enum Constants

Enum Constant	Description
DROPPED	The snippet is inactive because of an explicit call to the JShell.drop(Snippet).
NONEXISTENT	The snippet is inactive because it does not yet exist.
OVERWRITTEN	The snippet is inactive because it has been replaced by a new snippet.
RECOVERABLE_DEFINED	The snippet is a declaration snippet with potentially recoverable unresolved references or other issues in its body (in the context of current JShell state).
RECOVERABLE_NOT_DEFINED	The snippet is a declaration snippet with potentially recoverable unresolved references or other issues (in the context of current JShell state).
REJECTED	The snippet is inactive because it failed compilation on initial evaluation and it is not capable of becoming valid with further changes to the JShell state.
VALID	The snippet is a valid snippet (in the context of current JShell state).

Method Summary

Modifier and Type	Method	Description
boolean	isActive()	Indicates whether the Snippet is active, that is, will a persistent snippet be re-evaluated when a new JShell.eval(String) or JShell.drop(Snippet) that could change its status is invoked.
boolean	isDefined()	Indicates whether the snippet is currently part of the defined state of the JShell.
static Snippet.Status	valueOf(String name)	Returns the enum constant of this type with the specified name.
static Snippet.Status[]	values()	Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

VALID

public static final Snippet.Status VALID

The snippet is a valid snippet (in the context of current JShell state). Only snippets with VALID Status can be executed (though not all VALID snippets have executable code).

The snippet is defined (isDefined() == true). If the snippet is a declaration or import (Snippet.Kind.isPersistent()), it is visible to other snippets

The snippet will update as dependents change (isActive() == true), its status could become RECOVERABLE_DEFINED, RECOVERABLE_NOT_DEFINED, DROPPED, or OVERWRITTEN.

RECOVERABLE_DEFINED

public static final Snippet.Status RECOVERABLE_DEFINED

The snippet is a declaration snippet with potentially recoverable unresolved references or other issues in its body (in the context of current JShell state). Only a DeclarationSnippet can have this Status.

The snippet has a valid signature and it is visible to other snippets (isDefined() == true) and thus can be referenced in existing or new snippets but the snippet cannot be executed. An UnresolvedReferenceException will be thrown on an attempt to execute it.

The snippet will update as dependents change (isActive() == true), its status could become VALID, RECOVERABLE_NOT_DEFINED, DROPPED, or OVERWRITTEN.

Note: both RECOVERABLE_DEFINED and RECOVERABLE_NOT_DEFINED indicate potentially recoverable errors, they differ in that, for RECOVERABLE_DEFINED, the snippet is defined.

RECOVERABLE_NOT_DEFINED

public static final Snippet.Status RECOVERABLE_NOT_DEFINED

The snippet is a declaration snippet with potentially recoverable unresolved references or other issues (in the context of current JShell state). Only a DeclarationSnippet can have this Status.

The snippet has an invalid signature or the implementation is otherwise unable to define it. The snippet it is not visible to other snippets (isDefined() == false) and thus cannot be referenced or executed.

The snippet will update as dependents change (isActive() == true), its status could become VALID, RECOVERABLE_DEFINED, DROPPED, or OVERWRITTEN.

Note: both RECOVERABLE_DEFINED and RECOVERABLE_NOT_DEFINED indicate potentially recoverable errors, they differ in that, for RECOVERABLE_DEFINED, the snippet is defined.

DROPPED

public static final Snippet.Status DROPPED

The snippet is inactive because of an explicit call to the JShell.drop(Snippet).

The snippet is not visible to other snippets (isDefined() == false) and thus cannot be referenced or executed.

The snippet will not update as dependents change (isActive() == false), its Status will never change again.

OVERWRITTEN

public static final Snippet.Status OVERWRITTEN

The snippet is inactive because it has been replaced by a new snippet. This occurs when the new snippet added with JShell.eval matches a previous snippet. A TypeDeclSnippet will match another TypeDeclSnippet if the names match. For example class X { } will overwrite class X { int ii; } or interface X { }. A MethodSnippet will match another MethodSnippet if the names and parameter types match. For example void m(int a) { } will overwrite int m(int a) { return a+a; }. A VarSnippet will match another VarSnippet if the names match. For example double z; will overwrite long z = 2L;. Only a PersistentSnippet can have this Status.

The snippet is not visible to other snippets (isDefined() == false) and thus cannot be referenced or executed.

The snippet will not update as dependents change (isActive() == false), its Status will never change again.

REJECTED

public static final Snippet.Status REJECTED

The snippet is inactive because it failed compilation on initial evaluation and it is not capable of becoming valid with further changes to the JShell state.

The snippet is not visible to other snippets (isDefined() == false) and thus cannot be referenced or executed.

The snippet will not update as dependents change (isActive() == false), its Status will never change again.

NONEXISTENT

public static final Snippet.Status NONEXISTENT

The snippet is inactive because it does not yet exist. Used only in SnippetEvent.previousStatus for new snippets. JShell.status(Snippet) will never return this Status.

Vacuously, isDefined() and isActive() are both defined false.

Method Detail

values

public static Snippet.Status[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (Snippet.Status c : Snippet.Status.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static Snippet.Status valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null

isActive

public boolean isActive()

Indicates whether the Snippet is active, that is, will a persistent snippet be re-evaluated when a new JShell.eval(String) or JShell.drop(Snippet) that could change its status is invoked. This is more broad than isDefined() since a Snippet which is RECOVERABLE_NOT_DEFINED will be updated.

Returns:

true if the Snippet is active; otherwise false

isDefined

public boolean isDefined()

Indicates whether the snippet is currently part of the defined state of the JShell. Is it visible to compilation of other snippets?

Returns:

true if the Snippet is defined; otherwise false