Here you can find the source of cast(Set> p)
public static <T> Set<T> cast(Set<?> p)
//package com.java2s; /*/*from w ww .j av a2 s .c o m*/ * Copyright LGPL3 * YES Technology Association * http://yestech.org * * http://www.opensource.org/licenses/lgpl-3.0.html */ import java.util.*; public class Main { public static <T, U> Map<T, U> cast(Map<?, ?> p) { return (Map<T, U>) p; } public static <T, U> Map<T, U> cast(Map<?, ?> p, Class<T> t, Class<U> u) { return (Map<T, U>) p; } public static <T> Collection<T> cast(Collection<?> p) { return (Collection<T>) p; } public static <T> Collection<T> cast(Collection<?> p, Class<T> cls) { return (Collection<T>) p; } public static <T> List<T> cast(List<?> p) { return (List<T>) p; } public static <T> List<T> cast(List<?> p, Class<T> cls) { return (List<T>) p; } public static <T> Iterator<T> cast(Iterator<?> p) { return (Iterator<T>) p; } public static <T> Iterator<T> cast(Iterator<?> p, Class<T> cls) { return (Iterator<T>) p; } public static <T> Set<T> cast(Set<?> p) { return (Set<T>) p; } public static <T> Set<T> cast(Set<?> p, Class<T> cls) { return (Set<T>) p; } public static <T, U> Map.Entry<T, U> cast(Map.Entry<?, ?> p) { return (Map.Entry<T, U>) p; } public static <T, U> Map.Entry<T, U> cast(Map.Entry<?, ?> p, Class<T> pc, Class<U> uc) { return (Map.Entry<T, U>) p; } }