I Wanted Orange (The machine would not make a mistake.)

File src = new File("test.fgd");
FgdSpec spec = new FgdSpec();
// If test.fgd uses an @include statement to 
// get another FGD, the DefaultLoader 
// will automatically handle it.
DefaultLoader.fillSpec(src,spec);
// Now you can pull information from spec
for(String name : spec.getEntClassNames()){
    FgdEntClass eclass = spec.getEntClass(name);
    System.out.println("Class "+name+" found of type "+eclass.getType());
}

Class base_prop_thing found of type BaseClass
Class prop_thingy found of type PointClass

FGD API example

Just a sample from the FGD code I wrote for the Hl2Parse library. This snippet loads the TF2 FGD file and then re-outputs the FGD format to show it has parsed everything. It also prints the "default" version and then the "combined" version which collapses all the inheritance.

final String fgdPath = "...";
FgdSpec spec = new FgdSpec();
spec.loadFrom(new File(fgd));

final String entName = "func_respawnroom";
FgdEntClass spawnroom = spec.getEntClass(entName); // Get normal version
System.out.println(spawnroom.toText(entName)); // Print sparse form

FgdEntClass combined = spawnroom.getInherited(spec); // Do inheritance
System.out.println(combined.toText(entName)); // Print comnined form

The first print statement replicates the set-up in the original file, using the base(...) modifier to do inheritance.

@SolidClass base(Targetname,TeamNum,EnableDisable,Toggle) = func_respawnroom :
"Designates a respawn room for a team." [
]

The second prints statement shows how it looks after the inheritance rules have been applied.

@SolidClass  = func_respawnroom :
"Designates a respawn room for a team." [
targetname(target_source) : "Name" : "" : "The name that other entities refer to this entity by."
StartDisabled(choices) : "Start Disabled" : 0 : "" =
[
0:"No"
1:"Yes"
]
TeamNum(choices) : "Team" : 0 : "Team" =
[
0:"Any"
2:"Red"
3:"Blue"
]
input KillHierarchy(void) : "Removes this entity and all its children from the world."
input Enable(void) : "Enable this entity."
input Disable(void) : "Disable this entity."
input SetTeam(integer) : "Changes the entity's team."
input Kill(void) : "Removes this entity from the world."
input FireUser4(void) : "Causes this entity's OnUser4 output to be fired."
input FireUser3(void) : "Causes this entity's OnUser3 output to be fired."
input FireUser2(void) : "Causes this entity's OnUser2 output to be fired."
input AddOutput(string) : "Adds an entity I/O connection to this entity. Format: <output name> <targetname>:<inputname>:<parameter>:<delay>:<max times to fire (-1 == infinite)>. Very dangerous, use with care."
input FireUser1(void) : "Causes this entity's OnUser1 output to be fired."
input Toggle(void) : "Toggle the enabled/disabled status of this entity."
output OnUser1(void) : "Fired in response to FireUser1 input."
output OnUser4(void) : "Fired in response to FireUser4 input."
output OnUser2(void) : "Fired in response to FireUser2 input."
output OnUser3(void) : "Fired in response to FireUser3 input."
]