E-Attributes are what eclipse uses to represent the parameters of a launch configuration. They are nothing more than a key->value mapping with a special XML syntax, and are represented in java as a TreeMap<String, Object>.
Each E-Attribute infers its Java type from its XML element name, and supplies a key XML attribute which will be used in the TreeMap. The location of the E-Attribute's value depends on the type.
The information in this documentd was sourced from here.
E-Attributes can be grouped into two categories, depending on how their value is stored. The first category is Primitive E-Attributes, representing strings, booleans, and integers. Primitive types always store their value in the XML attribute value within their XML element.
The remaining types are Collection E-Attributes, composed of sets, maps, and lists. These types store their values in sub-elements, which are specific "collection entry" E-Attributes that can only be used within the relevant collection.
The list of valid E-Attribute type names is as follows:
stringAttributeintAttributebooleanAttributesetAttribute
mapAttribute
listAttribute
All primitive elements take the form
<type key="myKey" value="myValue"/>
Thus, the syntax for the three primitive is:
<stringAttribute key="myString" value="aStringValue"/>
<intAttribute key="myInt" value="100"/>
<booleanAttribute key="myBool" value="false"/>
The value of stringAttribute may be any string.
The value of intAttribute must be an integer.
The value of booleanAttribute must be true or false.
Sets are an element of type setAttribute made up of child elements, each with the type setEntry, and each specifying the value attribute. Sets do not permit duplicate elements. The value of a setEntry is not explicitly typed. The expected data is application-specific.
<setAttribute key="mySet">
<setEntry value="first"/>
<setEntry value="second"/>
</setAttribute>Maps are an element of type mapAttribute made up of child elements of type mapEntry that specify the key and value attributes. Sets do not permit duplicate elements. The value of a setEntry is not explicitly typed. The expected data is application-specific.
<mapAttribute key="myMap">
<mapEntry key="one" value="first"/>
<mapEntry key="two" value="second"/>
</mapAttribute>Lists are similar to sets, but with type listAttribute and with sub-elements of type listEntry. Lists retain their order and permit duplicates. The value of a listEntry is not explicitly typed. The expected data is application-specific.
<listAttribute key="myList">
<listEntry value="first"/>
<listEntry value="second"/>
</listAttribute>