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<TITLE>Serializing an Immutable Bean Property to XML
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<h3>
e10.
Serializing an Immutable Bean Property to XML</h3>
An immutable property is one where the value is supplied to the
constructor rather than through a setter method. By default,
immutable properties are not persisted. This example demonstrates how
to persist an immutable property called <code>prop</code>.
<pre>
// Create an object with an immutable property and set the value
// of the immutable property in the constructor
<font color="#0066ff"><i>MyClass3</i></font> o = new <font color="#0066ff"><i>MyClass3</i></font>(<font color="#0066ff"><i>123</i></font>);
try {
// Create the encoder
XMLEncoder encoder = new XMLEncoder(new BufferedOutputStream(
new FileOutputStream(<font color="#0066ff"><i>"outfilename.xml"</i></font>)));
// Specify to the encoder, the name of the property that is associated
// with the constructor's parameter(s)
String[] propertyNames = new String[]{<font color="#0066ff"><i>"prop"</i></font>};
encoder.setPersistenceDelegate(<font color="#0066ff"><i>MyClass3</i></font>.class,
new DefaultPersistenceDelegate(propertyNames);
// Serialize the object into XML
encoder.writeObject(o);
encoder.close();
} catch (FileNotFoundException e) {
}
</pre>
<pre>
// This class defines an immutable property called prop.
// The value of the immutable property is initialized
import java.beans.*;
public class <font color="#0066ff"><i>MyClass3</i></font> {
int prop;
// The constructor that initializes the immutable property prop
public <font color="#0066ff"><i>MyClass3</i></font>(int prop) {
this.prop = prop;
}
// The immutable property
public int getProp() {
return prop;
}
}
</pre>
Here is the XML data:
<pre>
<?xml version="1.0" encoding="UTF-8"?>
<java version="1.4.0" class="java.beans.XMLDecoder">
<object class="MyClass3">
<int>123</int>
</object>
</java>
</pre>
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Related Examples
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e7. <a class="eglink" href="WriteXml.html?l=rel">
Serializing a Bean to XML
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e8. <a class="eglink" href="ReadXml.html?l=rel">
Deserializing a Bean from XML
</a>
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e9. <a class="eglink" href="MakeTrans.html?l=rel">
Preventing a Bean Property from Being Serialized to XML
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See also:
<a class="eglink" href="/egs/java.beans/pkg.html?l=rel#Events">
Events
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