Question

There is my actual solution to add a value to a hashmap

private HashMap<String,Sexpr> contexte = new HashMap<String,Sexpr>();

...

this.putVariable("car",Car.CAR);
this.putVariable("cdr",Cdr.CDR);

I want to do the same thing from a XML by using SAX

<root>
    <!-- Les types prédéfinis -->
      <type symbole="car" type="expr" class="Car.CAR"/>
      <type symbole="cdr" type="expr" class="Cdr.CDR"/>    
</root>

I can get theses values from my handler (with Sax) by using
attributes.getValue(i).toString(), i’d like to convert my string to Java Code for the second part of my request to access my class Car or Cdr in this example

X.putVariable(attributes.getValue(0).toString, attributes.getValue(2).? );

Thank you for your help

Answer 1

It looks like you will have to use reflection to retrieve the static member (called a Field in the Java reflection APIs) named in the “class” attribute. For example (untested):

public static Object lookupStaticMember(String name) /* throws many */ {
  String classField[] = name.split("\\.");
  Class<?> klass = Class.forName(classField[0]);
  Field field = klass.getField(classField[1]);
  int mods = field.getModifiers();
  if ((Modifier.PUBLIC & mods == 0) || (Modifier.STATIC & mods == 0)) {
    throw new IllegalArgumentException("field " + name + " is not public static");
  }
  return field.get(klass);
}

Now you can use it as:

X.putVariable(attributes.getValue(0).toString(),
    (Sexpr) lookupStaticMember(attributes.getValue(2).toString()));