Java to Go 学习指南

正文

这篇指南为了能够帮助Java程序员快速深入了解Go语言特性！

主要区别

面向对象：

• Go 语言的面向对象编程(OOP)非常简洁而优雅。说它简洁，简洁之处在于，它没有了OOP中很多概念，比如：继承、虚函数、构造函数和析构函数、隐藏的this指针等等。说它优雅，是它的面向对象(OOP)是语言类型系统(type system)中的天然的一部分。整个类型系统通过接口(interface)串联，浑然一体。

employee.go

1. package employee
3. import (
4. "fmt"
5. )
7. type employee struct {
8. firstName string
9. lastName string
10. totalLeaves int
11. leavesTaken int
12. }
14. func New(firstName string, lastName string, totalLeave int, leavesTaken int) employee {
15. e := employee {firstName, lastName, totalLeave, leavesTaken}
16. return e
17. }
19. func (e *employee) LeavesRemaining() {
20. fmt.Printf("%s %s has %d leaves remaining", e.firstName, e.lastName, (e.totalLeaves - e.leavesTaken))
21. }

main.go

1. package main
3. import "oop/employee"
5. func main() {
6. e := employee.New("Sam", "Adolf", 30, 20)
7. e.LeavesRemaining()
8. }

Go interface

1. package main
3. import "fmt"
4. import "math"
6. // Here's a basic interface for geometric shapes.
7. type geometry interface {
8. area() float64
9. perim() float64
10. }
12. // For our example we'll implement this interface on
13. // `rect` and `circle` types.
14. type rect struct {
15. width, height float64
16. }
17. type circle struct {
18. radius float64
19. }
21. // To implement an interface in Go, we just need to
22. // implement all the methods in the interface. Here we
23. // implement `geometry` on `rect`s.
24. func (r rect) area() float64 {
25. return r.width * r.height
26. }
27. func (r rect) perim() float64 {
28. return 2*r.width + 2*r.height
29. }
31. // The implementation for `circle`s.
32. func (c circle) area() float64 {
33. return math.Pi * c.radius * c.radius
34. }
35. func (c circle) perim() float64 {
36. return 2 * math.Pi * c.radius
37. }
39. // If a variable has an interface type, then we can call
40. // methods that are in the named interface. Here's a
41. // generic `measure` function taking advantage of this
42. // to work on any `geometry`.
43. func measure(g geometry) {
44. fmt.Println(g)
45. fmt.Println(g.area())
46. fmt.Println(g.perim())
47. }
49. func main() {
50. r := rect{width: 3, height: 4}
51. c := circle{radius: 5}
53. // The `circle` and `rect` struct types both
54. // implement the `geometry` interface so we can use
55. // instances of
56. // these structs as arguments to `measure`.
57. measure(r)
58. measure(c)
59. }

方法：

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