JAVA——List中剔除空元素（null）的三种方法汇总

JAVA——List中剔除空元素（null）的三种方法汇总

1、 list.removeAll(Collections.singleton(null));

List<String> list = new ArrayList<String>();
        list.add("");
        list.add("a");
        list.add(null);
        list.add(" ");
        System.out.println(list);
        System.out.println(list.size());
        list.removeAll(Collections.singleton(null));
        System.out.println(list);
        System.out.println(list.size());

2、
List nullList = new ArrayList();
nullList.add(null);
list.removeAll(nullList);

 List<String> list = new ArrayList<String>();
        list.add("");
        list.add("a");
        list.add(null);
        list.add(" ");
        System.out.println(list);
        System.out.println(list.size());
        List l = new ArrayList();
        l.add(null);
        list.removeAll(l);
        System.out.println(list);
        System.out.println(list.size());

3、使用迭代器

 List<String> list = new ArrayList<String>();
        list.add("");
        list.add("a");
        list.add(null);
        list.add(" ");
         System.out.println(list);
        System.out.println(list.size());
        Iterator iterator = list.iterator();
        while (iterator.hasNext()) {
            if(null == iterator.next()){
                iterator.remove();
            }
        }
        System.out.println(list);
        System.out.println(list.size());