Map<String, Object> map = new HashMap();
map.put("obj",1);
String s = (String) map.get("obj");
A type conversion exception will occur in the third line above, you need to pay attention
Map<String, Object> map = new HashMap();
map.put("obj",1);
String s = (String) map.get("obj");
A type conversion exception will occur in the third line above, you need to pay attention