Java多态和向下转换

getFields()

public static void display(Integer i)
{
    System.out.println(\"An integer: \" + i);
}

// Basically a method for each primitive type wrapper

public static void display(Object o)
{
    for (Field f : c.getFields())
    {
        System.out.println(\"A \" + o.getClass() + \" which is composed of:\");
        display(f.get(o));
    }
}

Field

get

Object

display(Object o)

public static void display(Object o)
{
    if (o instanceof Integer)
    {
        display((Integer) o);
        return;
    }
    else if (o instanceof String 
    {
        ... 
    } // And so on

    for (Field f : c.getFields())
    {
        System.out.println(\"A \" + o.getClass() + \" which is composed of:\");
        display(f.get(o));
    }
}