Question

怎样修改map中指定key的值

Answer 1

Map<String,String> map = new HashMap();
map.put("1", "A");
map.put("2", "B");
map.put("3", "c");
Map<String,String> new_map = new HashMap();
for(String key:map.keySet()){
new_map.put(key+"_old", map.get(key));
}