遍历List、Map删除元素

List<String> list = new ArrayList<>();
list.add("1");
list.add("2");
list.add("3");
list.add(null);
list.add("5");

for(int i=0; i<list.size(); i++){
    list.remove(i);
    i--;
}
System.out.println(list.size());

List<String> list = new ArrayList<>();
list.add("1");
list.add("2");
list.add("3");
list.add(null);
list.add("5");
for (Iterator iterator = list.iterator(); iterator.hasNext();) {
    String tmp = (String)iterator.next();
    iterator.remove();
}
System.out.println(list.size());

 1 Map<String,String> map = new HashMap<>();
 2 map.put("1","aaa");
 3 map.put("2","bbb");
 4 map.put("3","ccc");
 5 map.put("4","ddd");
 6 map.put("5","eee");
 7 
 8 Iterator<Map.Entry<String, String>> it = map.entrySet().iterator();
 9 while (it.hasNext()) {
10     Map.Entry<String, String> entry = it.next();
11     it.remove();
12 }
13 System.out.println(map.size());

Map<String,String> map = new HashMap<>();
map.put("1","aaa");
map.put("2","bbb");
map.put("3","ccc");
map.put("4","ddd");
map.put("5","eee");

for (Iterator<Map.Entry<String, String>> it = map.entrySet().iterator(); it.hasNext();) {
    Map.Entry<String, String> entry = it.next();
    it.remove();
}
System.out.println(map.size());