netbeans.apache.org/src/content/wiki/DevFaqLookupGenerics.asciidoc

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= DevFaqLookupGenerics
:jbake-type: wiki
:jbake-tags: wiki, devfaq, needsreview
:jbake-status: published
:keywords: Apache NetBeans wiki DevFaqLookupGenerics
:description: Apache NetBeans wiki DevFaqLookupGenerics
:toc: left
:toc-title:
:syntax: true

=== How do I use Java Generics with Lookup?

As of NetBeans 6, a number of convenience methods have been added to lookup, and support for Java generics has been added to Lookup.  The following are differences (assume that `lkp` is a [[DevFaqLookup| `Lookup`]]):

|===
|NB 5.x Code  |NB 6 Code 

|`DataObject dob = (DataObject) lkp.lookup(DataObject.class)` |`DataObject dob = lkp.lookup(DataObject.class)` 

|`Lookup.Result r = lkp.lookup(new Lookup.Template(X.class))` |`Lookup.Result<? extends X> r = lkp.lookupResult(X.class)` 

|`Collection c = r.allInstances()` |`Collection<? extends X> c = r.allInstances()` 

|`Lookup.Template t = new Lookup.Template(X.class);

Lookup.Result r = lkp.lookup(t);

Collection c = r.allInstances();`

 |`Collection<? extends X> c = lkp.lookupAll(X.class);` 

|`Lookup.Template t = new Lookup.Template(X.class);

Lookup.Result r = lkp.lookup(t);

Collection c = r.allInstances(); 
`
`for (Iterator it=c.iterator(); it.hasNext();) {
&nbsp;&nbsp;X x = (X) it.next();

&nbsp;&nbsp;//do something with x

}`

 |`for (X x : lkp.lookupAll(X.class)) {

&nbsp;&nbsp;//do something with x

}`

 
|===



Generics work well with JDK-5-style for-loops:

[source,java]
----

for (SomeService s : Lookup.getDefault().lookupAll(SomeService.class)) {
    // ...
}
----

=== Apache Migration Information

The content in this page was kindly donated by Oracle Corp. to the
Apache Software Foundation.

This page was exported from link:http://wiki.netbeans.org/DevFaqLookupGenerics[http://wiki.netbeans.org/DevFaqLookupGenerics] , 
that was last modified by NetBeans user Tboudreau 
on 2010-02-19T00:29:05Z.


*NOTE:* This document was automatically converted to the AsciiDoc format on 2018-02-07, and needs to be reviewed.