package main import (     "fmt"     "sort" ) type MapSorter []Item type Item struct {     Key string     Val int64 } func NewMapSorter(m map[string]int64) MapSorter {     ms := make(MapSorter, 0, len(m))     for k, v := range m {         ms = append(ms, Item{k, v})     }     return ms } func (ms MapSorter) Len() int {     return len(ms) } func (ms MapSorter) Less(i, j int) bool {     return ms[i].Val < ms[j].Val // 按值排序     //return ms[i].Key < ms[j].Key // 按键排序 } func (ms MapSorter) Swap(i, j int) {     ms[i], ms[j] = ms[j], ms[i] } func main(){     m  := map[string]int64 {         "e": 10,         "a": 2,         "d": 15,         "c": 8,         "f": 1,         "b": 12,     }     ms := NewMapSorter(m)     sort.Sort(ms)     for _, item := range ms {         fmt.Printf("%s:%d\n", item.Key, item.Val)     } }