day9接口 排序接口

src/study/day9Interface/SortInterface.go

@@ -0,0 +1,112 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"sort"
+	"text/tabwriter"
+	"time"
+)
+
+type Interface interface {
+	// Len 方法返回集合中的元素个数
+	Len() int
+	// Less 方法报告索引i的元素是否比索引j的元素小
+	Less(i, j int) bool
+	// Swap 方法交换索引i和j的两个元素
+	Swap(i, j int)
+}
+
+// StringSlice 结构体实现了Interface接口
+type StringSlice []string
+
+// Len 方法返回集合中的元素个数
+func (p StringSlice) Len() int { return len(p) }
+
+// Less 方法报告索引i的元素是否比索引j的元素小
+func (p StringSlice) Less(i, j int) bool { return p[i] < p[j] }
+
+// Swap 交换元素
+func (p StringSlice) Swap(i, j int) { p[i], p[j] = p[j], p[i] }
+
+type Track struct {
+	Title  string
+	Artist string
+	Album  string
+	Year   int
+	Length time.Duration
+}
+
+var tracks = []*Track{
+	{"Go", "Delilah", "From the Roots Up", 2012, length("3m38s")},
+	{"Go", "Moby", "Moby", 1992, length("3m37s")},
+	{"Go Ahead", "Alicia Keys", "As I Am", 2007, length("4m36s")},
+	{"Ready 2 Go", "Martin Solveig", "Smash", 2011, length("4m24s")},
+}
+
+func length(s string) time.Duration {
+	d, err := time.ParseDuration(s)
+	if err != nil {
+		panic(s)
+	}
+	return d
+}
+func printTracks(tracks []*Track) {
+	const format = "%v\t%v\t%v\t%v\t%v\t\n"
+	tw := new(tabwriter.Writer).Init(os.Stdout, 0, 8, 2, ' ', 0)
+	fmt.Fprintf(tw, format, "Title", "Artist", "Album", "Year", "Length")
+	fmt.Fprintf(tw, format, "-----", "------", "-----", "----", "------")
+	for _, t := range tracks {
+		fmt.Fprintf(tw, format, t.Title, t.Artist, t.Album, t.Year, t.Length)
+	}
+	tw.Flush() // calculate column widths and print table
+}
+
+type byArtist []*Track
+
+func (x byArtist) Len() int           { return len(x) }
+func (x byArtist) Less(i, j int) bool { return x[i].Artist < x[j].Artist }
+func (x byArtist) Swap(i, j int)      { x[i], x[j] = x[j], x[i] }
+
+type byYear []*Track
+
+func (x byYear) Len() int           { return len(x) }
+func (x byYear) Less(i, j int) bool { return x[i].Year < x[j].Year }
+func (x byYear) Swap(i, j int)      { x[i], x[j] = x[j], x[i] }
+
+type customSort struct {
+	t    []*Track
+	less func(x, y *Track) bool
+}
+
+func (x customSort) Len() int           { return len(x.t) }
+func (x customSort) Less(i, j int) bool { return x.less(x.t[i], x.t[j]) }
+func (x customSort) Swap(i, j int)      { x.t[i], x.t[j] = x.t[j], x.t[i] }
+
+func main() {
+	nums := StringSlice([]string{"b", "f", "c", "a"})
+	sort.Sort(nums)
+	fmt.Println(nums)
+
+	printTracks(tracks)
+	fmt.Println()
+	sort.Sort(byArtist(tracks))
+	printTracks(tracks)
+	fmt.Println()
+	sort.Sort(sort.Reverse(byArtist(tracks)))
+	printTracks(tracks)
+
+	sort.Sort(customSort{tracks, func(x, y *Track) bool {
+		if x.Title != y.Title {
+			return x.Title < y.Title
+		}
+		if x.Year != y.Year {
+			return x.Year < y.Year
+		}
+		if x.Length != y.Length {
+			return x.Length < y.Length
+		}
+		return false
+	}})
+
+}