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<TITLE>Wrapping a Primitive Type in a Wrapper Object (Java Developers Almanac Example)
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<h3>e58. Wrapping a Primitive Type in a Wrapper Object</h3>
In the Java language, the eight primitive types --- <code>boolean</code>,
<code>byte</code>, <code>char</code>, <code>short</code>, <code>int</code>, <code>long</code>, <code>float</code>,
<code>double</code> --- are not objects. However, in certain situations,
objects are required. For example, collection classes such as <code>Map</code>
and <code>Set</code> only work with objects. This issue is addressed by
wrapping a primitive type in a <font color="#0066ff"><i>wrapper object</i></font>. There is a wrapper
object for each primitive type.
<P>
This example demonstrates how to wrap the value of a primitive type
in a wrapper object and then subsequently retrieve the value of the
primitive type.
<pre> // Create wrapper object for each primitive type
Boolean refBoolean = new Boolean(<font color="#0066ff"><i>true</i></font>);
Byte refByte = new Byte((byte)<font color="#0066ff"><i>123</i></font>);
Character refChar = new Character(<font color="#0066ff"><i>'x'</i></font>);
Short refShort = new Short((short)<font color="#0066ff"><i>123</i></font>);
Integer refInt = new Integer(<font color="#0066ff"><i>123</i></font>);
Long refLong = new Long(<font color="#0066ff"><i>123L</i></font>);
Float refFloat = new Float(<font color="#0066ff"><i>12.3F</i></font>);
Double refDouble = new Double(<font color="#0066ff"><i>12.3D</i></font>);
// Retrieving the value in a wrapper object
boolean bool = refBoolean.booleanValue();
byte b = refByte.byteValue();
char c = refChar.charValue();
short s = refShort.shortValue();
int i = refInt.intValue();
long l = refLong.longValue();
float f = refFloat.floatValue();
double d = refDouble.doubleValue();
</pre>
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<b>Related Examples</b></font></td>
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e56. <a class="eglink" href="CloneObject.html?l=rel">
Cloning an Object
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e57. <a class="eglink" href="GetHash.html?l=rel">
Comparing Object Values Using Hash Codes
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See also:
<a class="eglink" href="/egs/java.lang/pkg.html?l=rel#Arrays">
Arrays
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<a class="eglink" href="/egs/java.lang/pkg.html?l=rel#Assertions">
Assertions
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<a class="eglink" href="/egs/java.lang/pkg.html?l=rel#Classes">
Classes
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<a class="eglink" href="/egs/java.lang/pkg.html?l=rel#Commands">
Commands
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<a class="eglink" href="/egs/java.lang/pkg.html?l=rel#Numbers">
Numbers
</a>
<a class="eglink" href="/egs/java.lang/pkg.html?l=rel#Strings">
Strings
</a>
<a class="eglink" href="/egs/java.lang/pkg.html?l=rel#System%20Properties">
System Properties
</a>
<a class="eglink" href="/egs/java.lang/pkg.html?l=rel#Threads">
Threads
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