Package org.apache.commons.lang3

Class ThreadUtils

java.lang.Object

org.apache.commons.lang3.ThreadUtils

public class ThreadUtils
extends java.lang.Object

Helpers for java.lang.Thread and java.lang.ThreadGroup.

#ThreadSafe#

Since:

3.5

See Also:

Thread, ThreadGroup

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ThreadUtils.NamePredicate	A predicate implementation which matches a thread or threadgroup name.
static interface	ThreadUtils.ThreadGroupPredicate	A predicate for selecting threadgroups.
static class	ThreadUtils.ThreadIdPredicate	A predicate implementation which matches a thread id.
static interface	ThreadUtils.ThreadPredicate	A predicate for selecting threads.

Field Summary

Fields

Modifier and Type	Field	Description
static org.apache.commons.lang3.ThreadUtils.AlwaysTruePredicate	ALWAYS_TRUE_PREDICATE	Predicate which always returns true.

Constructor Summary

Constructors

Constructor	Description
ThreadUtils()	ThreadUtils instances should NOT be constructed in standard programming.

Method Summary

Modifier and Type	Method	Description
static java.lang.Thread	findThreadById(long threadId)	Return the active thread with the specified id.
static java.lang.Thread	findThreadById(long threadId, java.lang.String threadGroupName)	Return the active thread with the specified id if it belongs to a thread group with the specified group name.
static java.lang.Thread	findThreadById(long threadId, java.lang.ThreadGroup threadGroup)	Return the active thread with the specified id if it belongs to the specified thread group.
static java.util.Collection<java.lang.ThreadGroup>	findThreadGroups(java.lang.ThreadGroup group, boolean recurse, ThreadUtils.ThreadGroupPredicate predicate)	Select all active threadgroups which match the given predicate and which is a subgroup of the given thread group (or one of its subgroups).
static java.util.Collection<java.lang.ThreadGroup>	findThreadGroups(ThreadUtils.ThreadGroupPredicate predicate)	Select all active threadgroups which match the given predicate.
static java.util.Collection<java.lang.ThreadGroup>	findThreadGroupsByName(java.lang.String threadGroupName)	Return active thread groups with the specified group name.
static java.util.Collection<java.lang.Thread>	findThreads(java.lang.ThreadGroup group, boolean recurse, ThreadUtils.ThreadPredicate predicate)	Select all active threads which match the given predicate and which belongs to the given thread group (or one of its subgroups).
static java.util.Collection<java.lang.Thread>	findThreads(ThreadUtils.ThreadPredicate predicate)	Select all active threads which match the given predicate.
static java.util.Collection<java.lang.Thread>	findThreadsByName(java.lang.String threadName)	Return active threads with the specified name.
static java.util.Collection<java.lang.Thread>	findThreadsByName(java.lang.String threadName, java.lang.String threadGroupName)	Return active threads with the specified name if they belong to a thread group with the specified group name.
static java.util.Collection<java.lang.Thread>	findThreadsByName(java.lang.String threadName, java.lang.ThreadGroup threadGroup)	Return active threads with the specified name if they belong to a specified thread group.
static java.util.Collection<java.lang.ThreadGroup>	getAllThreadGroups()	Return all active thread groups excluding the system thread group (A thread group is active if it has been not destroyed).
static java.util.Collection<java.lang.Thread>	getAllThreads()	Return all active threads (A thread is active if it has been started and has not yet died).
static java.lang.ThreadGroup	getSystemThreadGroup()	Return the system thread group (sometimes also referred as "root thread group").

Methods inherited from class java.lang.Object

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

Field Detail

ALWAYS_TRUE_PREDICATE

public static final org.apache.commons.lang3.ThreadUtils.AlwaysTruePredicate ALWAYS_TRUE_PREDICATE

Predicate which always returns true.

Constructor Detail

ThreadUtils

public ThreadUtils()

ThreadUtils instances should NOT be constructed in standard programming. Instead, the class should be used as ThreadUtils.getAllThreads()

This constructor is public to permit tools that require a JavaBean instance to operate.

Method Detail

findThreadById

public static java.lang.Thread findThreadById(long threadId,
                                              java.lang.ThreadGroup threadGroup)

Return the active thread with the specified id if it belongs to the specified thread group.

Parameters:

threadId - The thread id

threadGroup - The thread group

Returns:

The thread which belongs to a specified thread group and the thread's id match the specified id. null is returned if no such thread exists

Throws:

java.lang.IllegalArgumentException - if the specified id is zero or negative or the group is null

java.lang.SecurityException - if the current thread cannot access the system thread group

java.lang.SecurityException - if the current thread cannot modify thread groups from this thread's thread group up to the system thread group

findThreadById

public static java.lang.Thread findThreadById(long threadId,
                                              java.lang.String threadGroupName)

Return the active thread with the specified id if it belongs to a thread group with the specified group name.

Parameters:

threadId - The thread id

threadGroupName - The thread group name

Returns:

The threads which belongs to a thread group with the specified group name and the thread's id match the specified id. null is returned if no such thread exists

Throws:

java.lang.IllegalArgumentException - if the specified id is zero or negative or the group name is null

java.lang.SecurityException - if the current thread cannot access the system thread group

java.lang.SecurityException - if the current thread cannot modify thread groups from this thread's thread group up to the system thread group

findThreadsByName

public static java.util.Collection<java.lang.Thread> findThreadsByName(java.lang.String threadName,
                                                                       java.lang.ThreadGroup threadGroup)

Return active threads with the specified name if they belong to a specified thread group.

Parameters:

threadName - The thread name

threadGroup - The thread group

Returns:

The threads which belongs to a thread group and the thread's name match the specified name, An empty collection is returned if no such thread exists. The collection returned is always unmodifiable.

Throws:

java.lang.IllegalArgumentException - if the specified thread name or group is null

java.lang.SecurityException - if the current thread cannot access the system thread group

java.lang.SecurityException - if the current thread cannot modify thread groups from this thread's thread group up to the system thread group

findThreadsByName

public static java.util.Collection<java.lang.Thread> findThreadsByName(java.lang.String threadName,
                                                                       java.lang.String threadGroupName)

Return active threads with the specified name if they belong to a thread group with the specified group name.

Parameters:

threadName - The thread name

threadGroupName - The thread group name

Returns:

The threads which belongs to a thread group with the specified group name and the thread's name match the specified name, An empty collection is returned if no such thread exists. The collection returned is always unmodifiable.

Throws:

java.lang.IllegalArgumentException - if the specified thread name or group name is null

java.lang.SecurityException - if the current thread cannot access the system thread group

java.lang.SecurityException - if the current thread cannot modify thread groups from this thread's thread group up to the system thread group

findThreadGroupsByName

public static java.util.Collection<java.lang.ThreadGroup> findThreadGroupsByName(java.lang.String threadGroupName)

Return active thread groups with the specified group name.

Parameters:

threadGroupName - The thread group name

Returns:

the thread groups with the specified group name or an empty collection if no such thread group exists. The collection returned is always unmodifiable.

Throws:

java.lang.IllegalArgumentException - if group name is null

java.lang.SecurityException - if the current thread cannot access the system thread group

java.lang.SecurityException - if the current thread cannot modify thread groups from this thread's thread group up to the system thread group

getAllThreadGroups

public static java.util.Collection<java.lang.ThreadGroup> getAllThreadGroups()

Return all active thread groups excluding the system thread group (A thread group is active if it has been not destroyed).

Returns:

all thread groups excluding the system thread group. The collection returned is always unmodifiable.

Throws:

java.lang.SecurityException - if the current thread cannot access the system thread group

java.lang.SecurityException - if the current thread cannot modify thread groups from this thread's thread group up to the system thread group

getSystemThreadGroup

public static java.lang.ThreadGroup getSystemThreadGroup()

Return the system thread group (sometimes also referred as "root thread group").

Returns:

the system thread group

Throws:

java.lang.SecurityException - if the current thread cannot modify thread groups from this thread's thread group up to the system thread group

getAllThreads

public static java.util.Collection<java.lang.Thread> getAllThreads()

Return all active threads (A thread is active if it has been started and has not yet died).

Returns:

all active threads. The collection returned is always unmodifiable.

Throws:

java.lang.SecurityException - if the current thread cannot access the system thread group

java.lang.SecurityException - if the current thread cannot modify thread groups from this thread's thread group up to the system thread group

findThreadsByName

public static java.util.Collection<java.lang.Thread> findThreadsByName(java.lang.String threadName)

Return active threads with the specified name.

Parameters:

threadName - The thread name

Returns:

The threads with the specified name or an empty collection if no such thread exists. The collection returned is always unmodifiable.

Throws:

java.lang.IllegalArgumentException - if the specified name is null

java.lang.SecurityException - if the current thread cannot access the system thread group

java.lang.SecurityException - if the current thread cannot modify thread groups from this thread's thread group up to the system thread group

findThreadById

public static java.lang.Thread findThreadById(long threadId)

Return the active thread with the specified id.

Parameters:

threadId - The thread id

Returns:

The thread with the specified id or null if no such thread exists

Throws:

java.lang.IllegalArgumentException - if the specified id is zero or negative

java.lang.SecurityException - if the current thread cannot access the system thread group

java.lang.SecurityException - if the current thread cannot modify thread groups from this thread's thread group up to the system thread group

findThreads

public static java.util.Collection<java.lang.Thread> findThreads(ThreadUtils.ThreadPredicate predicate)

Select all active threads which match the given predicate.

Parameters:

predicate - the predicate

Returns:

An unmodifiable Collection of active threads matching the given predicate

Throws:

java.lang.IllegalArgumentException - if the predicate is null

java.lang.SecurityException - if the current thread cannot access the system thread group

java.lang.SecurityException - if the current thread cannot modify thread groups from this thread's thread group up to the system thread group

findThreadGroups

public static java.util.Collection<java.lang.ThreadGroup> findThreadGroups(ThreadUtils.ThreadGroupPredicate predicate)

Select all active threadgroups which match the given predicate.

Parameters:

predicate - the predicate

Returns:

An unmodifiable Collection of active threadgroups matching the given predicate

Throws:

java.lang.IllegalArgumentException - if the predicate is null

java.lang.SecurityException - if the current thread cannot access the system thread group

java.lang.SecurityException - if the current thread cannot modify thread groups from this thread's thread group up to the system thread group

findThreads

public static java.util.Collection<java.lang.Thread> findThreads(java.lang.ThreadGroup group,
                                                                 boolean recurse,
                                                                 ThreadUtils.ThreadPredicate predicate)

Select all active threads which match the given predicate and which belongs to the given thread group (or one of its subgroups).

Parameters:

group - the thread group

recurse - if true then evaluate the predicate recursively on all threads in all subgroups of the given group

predicate - the predicate

Returns:

An unmodifiable Collection of active threads which match the given predicate and which belongs to the given thread group

Throws:

java.lang.IllegalArgumentException - if the given group or predicate is null

java.lang.SecurityException - if the current thread cannot modify thread groups from this thread's thread group up to the system thread group

findThreadGroups

public static java.util.Collection<java.lang.ThreadGroup> findThreadGroups(java.lang.ThreadGroup group,
                                                                           boolean recurse,
                                                                           ThreadUtils.ThreadGroupPredicate predicate)

Select all active threadgroups which match the given predicate and which is a subgroup of the given thread group (or one of its subgroups).

Parameters:

group - the thread group

recurse - if true then evaluate the predicate recursively on all threadgroups in all subgroups of the given group

predicate - the predicate

Returns:

An unmodifiable Collection of active threadgroups which match the given predicate and which is a subgroup of the given thread group

Throws:

java.lang.IllegalArgumentException - if the given group or predicate is null

java.lang.SecurityException - if the current thread cannot modify thread groups from this thread's thread group up to the system thread group