= Solution
Replace type parameters by their erasures, normally `Object` or the first declared bound, and insert checked casts where an erased result is used as its former specific type. A simple <generics in Java> example becomes:
``
// Generic version
Vector<String> names = new Vector<String>();
names.add("Ada");
String s = names.get(0);
// Non-generic version
Vector names = new Vector();
names.add("Ada");
String s = (String) names.get(0);
``
The two fragments are alternatives, not consecutive declarations in one scope. For a user-defined `Box<T>`, replace fields, parameters and returns of type `T` by `Object`, and cast the retrieved result. Bounded parameters instead erase to their bound. A full translation must also preserve method dispatch where erasure changes overridden signatures, using suitable forwarding methods; this is the principle of <type erasure>, not simply deleting every pair of angle brackets.
The raw collection permits accidental insertion of an unrelated object, which may fail much later at a cast. The generic collection rejects such insertion during compilation, documents its contract at the declaration, and eliminates repetitive casts at use sites. \b[The generic version catches more errors earlier and expresses the programmer's intended element type directly.] Generic types are largely erased at runtime, so their advantage is static checking rather than a new runtime vector representation. The translation mechanism is specified by the https://docs.oracle.com/javase/specs/jls/se8/html/jls-4.html#jls-4.6[Java language specification].
Back to article page
