Java: Dynamic type casting using enums

casting, enums, java

Solution

`C` doesn't work, because `Columns.RANK.type` is not accessible at compile time.

However, `B` can be implemented using a custom generic-based class instead of `enum`:

class Columns<T>
{
    public static final Columns<String> RANK = new Columns<String>(0, "Rank", String.class);
    public static final Columns<Integer> NUMBER = new Columns<Integer>(1, "Number", Integer.class);

    public final Class<T> type;
    public final String text; 
    public final int index; 

    private Columns(int idx, String text, Class<T> clasz) 
    { 
        this.type = clasz; 
        this.text = text; 
        this.index = idx; 
    } 
}

Problem

I am trying to do something along the lines of: ``` public void setContents(Object[] values) { ... //A. this works mRank = ((String)(values[Columns.RANK.index])); //B. doesn't work (entire line underlined by netbeans) mRank = (Columns.RANK.type.cast(values[Columns.RANK.index])); //incompatible types: required java,lang.String found: java.lang.Object //C. doesn't work (first RANK is underlined by netbeans) mRank = ((Columns.RANK.type)(values[Columns.RANK.index])); //cannot find symbol symbol: class RANK location: blah.blah.Columns ... } ``` Where columns is an inner enum, like so: ``` public static enum Columns { RANK(0, "Rank", String.class), NUMBER(1, "Number", Integer.class); public String text; public Class type; public int index; private Columns(int idx, String text, Class clasz) { this.type = clasz; this.text = text; this.index = idx; } } ``` I understand why line `B` doesn't work, but what I don't get is why `C` doesn't work. If I use `Columns.RANK.type` anywhere else other than in a type cast, it works fine, but one I attempt to do a typecast with the class, it compiles saying it cannot find `RANK` in the enum, which shouldn't be the case. How to work around? Thanks!

Original source