JAXB Unmarshalling from Source example

Demo.java

import javax.xml.bind.*;
import javax.xml.transform.Source;
import javax.xml.transform.stream.StreamSource;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

public class Demo {
    public static void main(String[] args) throws JAXBException, IOException {
        JAXBContext context = JAXBContext.newInstance(Type.class, InnerType.class);
        Marshaller marshaller = context.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        Type type = new Type();
        type.setId("id");
        InnerType value = new InnerType("Pretty Value");
        type.setValue(value);
        File output = new File("type.xml");
        System.out.println(type);
        marshaller.marshal(type, output);

        Unmarshaller unmarshaller = context.createUnmarshaller();
        try (FileInputStream fis = new FileInputStream(output)) {
            Source source = new StreamSource(fis);
            JAXBElement<Type> element = unmarshaller.unmarshal(source, Type.class);
            Type typeFromXml = element.getValue();
            System.out.println(typeFromXml);
        }
    }
}

InnerType.java

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class InnerType {
    private String value;

    public InnerType() {
    }

    public InnerType(String value) {
        this.value = value;
    }

    public String getValue() {
        return value;
    }

    @Override
    public String toString() {
        final StringBuffer sb = new StringBuffer("InnerType{");
        sb.append("value='").append(value).append('\'');
        sb.append('}');
        return sb.toString();
    }
}

InnerTypeAdapter.java

import javax.xml.bind.annotation.adapters.XmlAdapter;

public class InnerTypeAdapter extends XmlAdapter<String, InnerType> {
    @Override
    public InnerType unmarshal(String v) throws Exception {
        return new InnerType(v);
    }

    @Override
    public String marshal(InnerType v) throws Exception {
        return v.getValue();
    }
}

Type.java

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;

@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement
public class Type {
    @XmlElement
    private String id;
    @XmlJavaTypeAdapter(InnerTypeAdapter.class)
    @XmlElement
    private InnerType value;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public InnerType getValue() {
        return value;
    }

    public void setValue(InnerType value) {
        this.value = value;
    }

    @Override
    public String toString() {
        final StringBuffer sb = new StringBuffer("Type{");
        sb.append("id='").append(id).append('\'');
        sb.append(", value=").append(value);
        sb.append('}');
        return sb.toString();
    }
}