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<TITLE>Storing Primitive Types in a Collection
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<h3>
e346.
Storing Primitive Types in a Collection</h3>
Collections can only store objects, not primitive types like <code>int</code>
and <code>double</code>. Primitive types must be placed in a <font color="#0066ff"><i>wrapper</i></font>
object before they can be placed in a collection. This example
demonstrates the storing of <code>int</code> values in a <code>Map</code>.
<P> See also: <a href="../java.lang/Wrap.html" class="eglink"><font size="-1"><b>e58</b> Wrapping a Primitive Type in a Wrapper Object</font></a>.
<pre>
// Create map
Map map = new HashMap();
// Create int wrapper object
Integer refInt = new Integer(<font color="#0066ff"><i>123</i></font>);
// Store int in map
map.put(<font color="#0066ff"><i>"key"</i></font>, refInt);
// Get int value from map
refInt = (Integer)map.get(<font color="#0066ff"><i>"key"</i></font>);
// Get the integer value from wrapper object
int i = refInt.intValue();
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Related Examples
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e342. <a class="eglink" href="coll_Queue.html?l=rel">
Implementing a Queue
</a>
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e343. <a class="eglink" href="coll_Stack.html?l=rel">
Implementing a Stack
</a>
<br>
e344. <a class="eglink" href="coll_Cache.html?l=rel">
Implementing a Least-Recently-Used (LRU) Cache
</a>
<br>
e345. <a class="eglink" href="coll_Iterate.html?l=rel">
Listing the Elements of a Collection
</a>
<br>
e347. <a class="eglink" href="coll_CreateCopy.html?l=rel">
Creating a Copy of a Collection
</a>
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e348. <a class="eglink" href="coll_MakeRo.html?l=rel">
Making a Collection Read-Only
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See also:
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Arrays">
Arrays
</a>
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Bits">
Bits
</a>
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Dates">
Dates
</a>
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Hash%20Tables">
Hash Tables
</a>
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Lists">
Lists
</a>
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Property%20Files">
Property Files
</a>
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Sets">
Sets
</a>
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Sorted%20Collections">
Sorted Collections
</a>
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Time">
Time
</a>
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Timers">
Timers
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