ConcurrentHashMap<String, Integer> hm = new ConcurrentHashMap<>();
hm.put("1", 1);
hm.put("2", 2);
hm.put("3", 3);
Iterator<String> itr = hm.keySet().iterator();
while(itr.hasNext()){
String key = itr.next();
System.out.println(key + " : " + hm.get(key));
hm.put("4", 4);
}
System.out.println(hm);
ConcurrentHashMap<String, Integer> hm1 = new ConcurrentHashMap<>();
hm1.put("One", 1);
hm1.put("Two", 2);
hm1.put("Three", 3);
Iterator<String> itr1 = hm1.keySet().iterator();
while(itr1.hasNext()){
String key = itr1.next();
System.out.println(key + " : " + hm1.get(key));
hm1.put("Four", 4);
}
System.out.println(hm1);
输出: 1 : 1 2 : 2 3 : 3 4 : 4 {1=1, 2=2, 3=3, 4=4} 一:1 二:2 三:3 {一=1,四=4,二=2, 三=3}
为什么这样?