Unmarshalling is a process of converting the byte stream back to their original data or object. The conversion is achieved through "serialization".
JAXB stand for Java Architecture for XML Binding. Jaxb allows us to map Java classes to XML representations. JAXB can be used Java to marshal java object into xml or/and to unmarshal XML back into Java objects.
I used these 2 jar for this example. You can download latest version of jar and add it to your class path.
Here is bookCatalog.xml, which we are going to unmarshall.
Here is BookCatalog.java. We are going to unmarshalled above xml into object of BookCatalog using Jaxb apis.
Source code of UnMarshalingMain.java is given below.