Find Objects with Specific Values
Find Handle Objects
Use the handle
class findobj
method
to find objects that have properties with specific values. For example,
the following class defines a PhoneBook
object
to represent a telephone book entry in a data base. The PhoneBook
class
subclasses the dynamicprops
class,
which derives from handle
.
classdef PhoneBook < dynamicprops properties Name Address Number end methods function obj = PhoneBook(n,a,p) obj.Name = n; obj.Address = a; obj.Number = p; end end end
Here are three of the PhoneBook
entries in
the database:
PB(1) = PhoneBook('Nancy Vidal','123 Washington Street','5081234567'); PB(2) = PhoneBook('Nancy Vidal','123 Main Street','5081234568'); PB(3) = PhoneBook('Nancy Wong','123 South Street','5081234569');
One of these three PhoneBook
objects has
a dynamic property:
PB(2).addprop('HighSpeedInternet'); PB(2).HighSpeedInternet = '1M';
Find Property/Value Pairs
Find the object representing employee Nancy
Wong
and
display the name and number by concatenating the strings:
NW = findobj(PB,'Name','Nancy Wong'); [NW.Name,' - ',NW.Number]
ans = Nancy Wong - 5081234569
Find Objects with Specific Property Names
Search for objects with specific property names using the -property
option:
H = findobj(PB,'-property','HighSpeedInternet'); H.HighSpeedInternet
ans = 1M
The -property
option enables you to omit
the value of the property and search for objects using only the property
name.
Using Logical Expressions
Search for specific combinations of property names and values:
H = findobj(PB,'Name','Nancy Vidal','-and','Address','123 Main Street'); H.Number
ans = 5081234568
Find by Attribute Settings
All metaclasses derive from the handle
class. You can use the handle
findobj
method
to find class members that have specific attribute settings.
For example, find the abstract methods in a class definition
by searching the meta.class
MethodList
for meta.method
objects
with their Abstract
property set to true
:
Use the class name in character format because class is abstract. You cannot create an object of the class:
mc = meta.class.fromName('MyClass');
Search the MethodList
list of meta.method
objects for those methods
that have their Abstract
property set to true
:
absMethods = findobj(mc.MethodList,'Abstract',true);
methodNames = {absMethods.Name};
The cell array, methodNames
, contains the
names of the abstract methods in the class.
Find Properties That Have Public Get Access
Find the names of all properties in the containers.Map
class
that have public GetAccess
:
Get the
meta.class
object.Use
findobj
to search the array ofmeta.property
objects.Use braces to create a cell array of property names.
mc = ?containers.Map; mpArray = findobj(mc.PropertyList,'GetAccess','public'); names = {mpArray.Name};
Display the names of all containers.Map
properties
that have public GetAccess
:
celldisp(names)
names{1} = Count names{2} = KeyType names{3} = ValueType
Find Static Methods
Determine if any containers.Map
class methods
are static:
~isempty(findobj([mc.MethodList(:)],'Static',true))
ans = 1
findobj
returns an array of meta.method
objects
for the static methods. In this case, the list of static methods is
not empty. Therefore, there are static methods defined by this class.
Get the names of any static methods from the meta.method
array:
staticMethodInfo = findobj([mc.MethodList(:)],'Static',true);
staticMethodInfo(:).Name
ans = empty
The name of the static method (there is only one in this case)
is empty
. Here is the information from the meta.method
object
for the empty
method:
staticMethodInfo
method with properties: Name: 'empty' Description: 'Returns an empty object array of the given size' DetailedDescription: '' Access: 'public' Static: 1 Abstract: 0 Sealed: 0 Hidden: 1 InputNames: {'varargin'} OutputNames: {'E'} DefiningClass: [1x1 meta.class]