Guava包，ImmutableSet,ImmutableList,ImmutableMap,Collections.unmodifiableList,不可变类，区别用法

    public void testJDKImmutable() {
        List<String> list = new ArrayList<String>();
        list.add("a");
        list.add("b");
        list.add("c");

        //通过list创建一个不可变的unmodifiableList集合
        List<String> unmodifiableList = Collections.unmodifiableList(list);
        System.out.println(unmodifiableList);

        //通过list添加元素
        list.add("ddd");
        System.out.println("往list添加一个元素:" + list);
        System.out.println("通过list添加元素之后的unmodifiableList:" + unmodifiableList);

        //通过unmodifiableList添加元素
        unmodifiableList.add("eee");
        System.out.println("往unmodifiableList添加一个元素:" + unmodifiableList);