Question

Say I have a Type a which is a java.util.TreeSet<T>, having been parameterized via a generic we can’t see due to type erasure. We also have a Type b, which is a ‘java.lang.Integer’. How do I construct a ParameterizedType that is a java.util.TreeSet<java.lang.Integer>?

Alternatively, if it’s any easier, we could have a raw java.util.TreeSet type to work with.

Answer 1

Implement ParameterizedType like so:

public class MyParamType implements ParameterizedType {
  private Type rawType;
  private List<Type> paramTypes;

  public MyParamType( Type raw ) {
    this.rawType = raw;
  }

  public void addParamType( Type t ) {
    paramTypes.add(t);
  }

  //for the interface methods, just return what you stored before
}

Do more or less the same for Type.
If you need more hints for what Type should actually implement for non-generic types (it’s only a marker interface), look at the JDK source or look at a concrete instance in the debugger.