Java tutorial
//package com.java2s; import java.util.*; public class Main { public static <T> List<T> immutableList(Collection<? extends T> list) { if (list == null) return Collections.emptyList(); return Collections .unmodifiableList(list instanceof List ? (List<? extends T>) list : new ArrayList<T>(list)); } public static <T> List<T> immutableList(T... list) { if (list == null) return Collections.emptyList(); return immutableList(Arrays.asList(list)); } }