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![VARIABLEN, SLICES, SCHLEIFEN
// Variable
var frank string = "Frank"
claire := "Claire"
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// Array (fixe Länge)
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namesArray := [3]string{frank, claire, "Zoe"}
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// Slice (variable Länge)
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namesSlice := make([]string, 2)
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namesSlice[0] = frank
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// Schleife
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for i, name := range namesSlice {
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fmt.Println("Hello " + name + "!")
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}
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// Array (fixe Länge)
namesArray := [3]string{frank, claire, "Zoe"}
// Variable
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var frank string = "Frank"
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claire := "Claire"
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// Slice (variable Länge)
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namesSlice := make([]string, 2)
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namesSlice[0] = frank
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// Schleife
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for i, name := range namesSlice {
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fmt.Println("Hello " + name + "!")
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}
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// Slice (variable Länge)
namesSlice := make([]string, 2)
namesSlice[0] = frank
// Variable
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var frank string = "Frank"
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claire := "Claire"
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// Array (fixe Länge)
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namesArray := [3]string{frank, claire, "Zoe"}
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// Schleife
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for i, name := range namesSlice {
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fmt.Println("Hello " + name + "!")
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}
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// Schleife
for i, name := range namesSlice {
fmt.Println("Hello " + name + "!")
}
// Variable
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var frank string = "Frank"
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claire := "Claire"
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// Array (fixe Länge)
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namesArray := [3]string{frank, claire, "Zoe"}
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// Slice (variable Länge)
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namesSlice := make([]string, 2)
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namesSlice[0] = frank
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15](https://image.slidesharecdn.com/2021-09-16javaforumnordjavatogo-210918161131/75/JavaForum-Nord-2021-Java-to-Go-Google-Go-fur-Java-Entwickler-10-2048.jpg)
![GENERICS
func printSliceOfInts(numbers []int) {
for _, num := range numbers {
fmt.Print(num, " ")
}
}
func printSliceOfStrings(strings []string) {
for _, num := range strings {
fmt.Print(num, " ")
}
}
Generics kommen in Go 2](https://image.slidesharecdn.com/2021-09-16javaforumnordjavatogo-210918161131/75/JavaForum-Nord-2021-Java-to-Go-Google-Go-fur-Java-Entwickler-17-2048.jpg)
Uploaded byJan Stamer
JavaForum Nord 2021: Java to Go - Google Go für Java-Entwickler
The document discusses transitioning from Java to Go, highlighting the advantages of Go such as simplicity, power, and built-in concurrency. It includes example codes demonstrating Go's syntax for variables, slices, structs, and goroutines alongside concepts like error handling and channels. Additionally, the document emphasizes Go's performance and native execution capabilities across various operating systems.
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Similar to JavaForum Nord 2021: Java to Go - Google Go für Java-Entwickler
JavaForum Nord 2021: Java to Go - Google Go für Java-Entwickler
- 1. JAVA TO GO GOOGLEGO FÜR JAVA ENTWICKLER
- 3. 467.882 ZEILEN CODE 2.130CONTRIBUTORS
- 5. 3 GRÜNDE FÜRGO 1 Einfach 2 Mächtig 3 Langweilig
- 7. HELLO GOPHER package main import"fmt" func main() { fmt.Println("Hello Gopher!") } Ausführen go build hellogopher.go // 1. Code kompilieren ./hellogopher // 2. Binary ausführen go run hellogopher.go // Code kompilieren und ausführen
- 8.
- 9. 5 FAKTEN ZUGO 1 statisches Typsystem 2 Garbage Collection 3 keine Vererbung 4 Concurrency eingebaut 5 native Ausführung Linux, Win, z/OS, 386, amd64, ARM, wasm, ...
- 10. VARIABLEN, SLICES, SCHLEIFEN //Variable var frank string = "Frank" claire := "Claire" 1 2 3 4 // Array (fixe Länge) 5 namesArray := [3]string{frank, claire, "Zoe"} 6 7 // Slice (variable Länge) 8 namesSlice := make([]string, 2) 9 namesSlice[0] = frank 10 11 // Schleife 12 for i, name := range namesSlice { 13 fmt.Println("Hello " + name + "!") 14 } 15 // Array (fixe Länge) namesArray := [3]string{frank, claire, "Zoe"} // Variable 1 var frank string = "Frank" 2 claire := "Claire" 3 4 5 6 7 // Slice (variable Länge) 8 namesSlice := make([]string, 2) 9 namesSlice[0] = frank 10 11 // Schleife 12 for i, name := range namesSlice { 13 fmt.Println("Hello " + name + "!") 14 } 15 // Slice (variable Länge) namesSlice := make([]string, 2) namesSlice[0] = frank // Variable 1 var frank string = "Frank" 2 claire := "Claire" 3 4 // Array (fixe Länge) 5 namesArray := [3]string{frank, claire, "Zoe"} 6 7 8 9 10 11 // Schleife 12 for i, name := range namesSlice { 13 fmt.Println("Hello " + name + "!") 14 } 15 // Schleife for i, name := range namesSlice { fmt.Println("Hello " + name + "!") } // Variable 1 var frank string = "Frank" 2 claire := "Claire" 3 4 // Array (fixe Länge) 5 namesArray := [3]string{frank, claire, "Zoe"} 6 7 // Slice (variable Länge) 8 namesSlice := make([]string, 2) 9 namesSlice[0] = frank 10 11 12 13 14 15
- 11. STRUCT STATT KLASSE typeCongressman struct { Name string } 1 2 3 4 func main() { 5 c := Congressman{Name: "Peter Russo"} 6 fmt.Println("Hello " + c.Name + "!") 7 } 8 c := Congressman{Name: "Peter Russo"} fmt.Println("Hello " + c.Name + "!") type Congressman struct { 1 Name string 2 } 3 4 func main() { 5 6 7 } 8 type Congressman struct { Name string } func main() { c := Congressman{Name: "Peter Russo"} fmt.Println("Hello " + c.Name + "!") } 1 2 3 4 5 6 7 8
- 12. FUNCTION RECEIVER STATTINSTANZMETHODE func (c Congressman) swearOathOfOffice() { fmt.Printf("I, %v, swear to serve the USA.", c.Name) } type Congressman struct { 1 Name string 2 } 3 4 5 6 7 8 func main() { 9 c := Congressman{Name: "Peter Russo"} 10 c.swearOathOfOffice(); 11 } 12 func (c Congressman) swearOathOfOffice() { fmt.Printf("I, %v, swear to serve the USA.", c.Name) } c := Congressman{Name: "Peter Russo"} c.swearOathOfOffice(); type Congressman struct { 1 Name string 2 } 3 4 5 6 7 8 func main() { 9 10 11 } 12
- 13. INTERFACE type Greeter interface{ greet() } 1 2 3 4 func passBy(c1 Greeter, c2 Greeter) 5 c1.greet() 6 c2.greet() 7 } 8 9 func main() { 10 c := Congressman{Name: "Frank U." 11 e := Enemy{} 12 passBy(c, e) 13 } 14 func passBy(c1 Greeter, c2 Greeter) c1.greet() c2.greet() } type Greeter interface { 1 greet() 2 } 3 4 5 6 7 8 9 func main() { 10 c := Congressman{Name: "Frank U." 11 e := Enemy{} 12 passBy(c, e) 13 } 14 func main() { c := Congressman{Name: "Frank U." e := Enemy{} passBy(c, e) } type Greeter interface { 1 greet() 2 } 3 4 func passBy(c1 Greeter, c2 Greeter) 5 c1.greet() 6 c2.greet() 7 } 8 9 10 11 12 13 14 type Greeter interface { greet() } 1 2 3 4 func passBy(c1 Greeter, c2 Greeter) 5 c1.greet() 6 c2.greet() 7 } 8 9 func main() { 10 c := Congressman{Name: "Frank U." 11 e := Enemy{} 12 passBy(c, e) 13 } 14 type Congressman struct { Name string } func (c Congressman) greet() { fmt.Println("Hello", c.Name) } type Enemy struct{} func (e Enemy) greet() { fmt.Println("Go to hell!") }
- 14.
- 15. STRUCT EMBEDDING STATTVERERBUNG type Congressman struct { Name string } 1 2 3 4 type President struct { 5 Congressman // Embedded 6 7 NuclearWeaponCode string 8 } 9 10 func main() { 11 p := President{NuclearWeaponCode: "123"} 12 p.Name = "Frank Underwood" 13 p.swearOathOfOffice(); 14 } 15 type President struct { Congressman // Embedded NuclearWeaponCode string } type Congressman struct { 1 Name string 2 } 3 4 5 6 7 8 9 10 func main() { 11 p := President{NuclearWeaponCode: "123"} 12 p.Name = "Frank Underwood" 13 p.swearOathOfOffice(); 14 } 15 p := President{NuclearWeaponCode: "123"} p.Name = "Frank Underwood" p.swearOathOfOffice(); type Congressman struct { 1 Name string 2 } 3 4 type President struct { 5 Congressman // Embedded 6 7 NuclearWeaponCode string 8 } 9 10 func main() { 11 12 13 14 } 15
- 16. FEHLER // Fehler alsRückgabewert func (c Congressman) bribe(amount float64) error { if c.Name != "Peter Russo" { return errors.New("Not corrupt!") } c.AccountBalance += amount return nil } 1 2 3 4 5 6 7 8 9 func main() { 10 c := Congressman{Name: "Jackie Sharp", AccountBalance: -10.0} 11 12 // Fehler behandeln 13 err := c.bribe(5000.0) 14 if err != nil { 15 fmt.Printf("%v is not bribable.", c.Name) 16 } 17 } 18 // Fehler behandeln err := c.bribe(5000.0) if err != nil { fmt.Printf("%v is not bribable.", c.Name) } // Fehler als Rückgabewert 1 func (c Congressman) bribe(amount float64) error { 2 if c.Name != "Peter Russo" { 3 return errors.New("Not corrupt!") 4 } 5 c.AccountBalance += amount 6 return nil 7 } 8 9 func main() { 10 c := Congressman{Name: "Jackie Sharp", AccountBalance: -10.0} 11 12 13 14 15 16 17 } 18
- 17. GENERICS func printSliceOfInts(numbers []int){ for _, num := range numbers { fmt.Print(num, " ") } } func printSliceOfStrings(strings []string) { for _, num := range strings { fmt.Print(num, " ") } } Generics kommen in Go 2
- 18.
- 19.
- 20. GOROUTINE func main() { goHelloCongressman("Russo") } func HelloCongressman(name string) { 1 fmt.Println("Hello Congressman", name) 2 } 3 4 5 6 7
- 21. GOROUTINE MIT SLEEP funcmain() { go HelloCongressman("Russo") func HelloCongressman(name string) { 1 fmt.Println("Hello Congressman", name) 2 } 3 4 5 6 7 time.Sleep(5 * time.Millisecond) 8 } 9 func main() { go HelloCongressman("Russo") time.Sleep(5 * time.Millisecond) func HelloCongressman(name string) { 1 fmt.Println("Hello Congressman", name) 2 } 3 4 5 6 7 8 } 9
- 22. GOROUTINE MIT WAITGROUP func main() { var waitGroup sync.WaitGroup waitGroup.Add(1) go func() { HelloCongressman("Russo") waitGroup.Done() }() waitGroup.Wait() } func HelloCongressman() { 1 fmt.Println("Hello Congressman", name) 2 } 3 4 5 6 7 8 9 10 11 12 13
- 23. GOROUTINE MIT WAITGROUP UND DEFER defer waitGroup.Done() HelloCongressman("Russo") func HelloCongressman() { 1 fmt.Println("Hello Congressman", name) 2 } 3 4 func main() { 5 var waitGroup sync.WaitGroup 6 waitGroup.Add(1) 7 go func() { 8 9 10 }() 11 waitGroup.Wait() 12 } 13
- 24. CHANNEL money := make(chanint) go Congressman(money) func main() { 1 2 3 4 // Nachricht senden 5 money <- 100 6 } 7 8 func Congressman(money chan int) { 9 // Nachricht empfangen 10 amount := <-money 11 12 fmt.Println("Received", amount, "$!") 13 } 14 // Nachricht senden money <- 100 func main() { 1 money := make(chan int) 2 go Congressman(money) 3 4 5 6 } 7 8 func Congressman(money chan int) { 9 // Nachricht empfangen 10 amount := <-money 11 12 fmt.Println("Received", amount, "$!") 13 } 14 func Congressman(money chan int) { // Nachricht empfangen amount := <-money fmt.Println("Received", amount, "$!") } func main() { 1 money := make(chan int) 2 go Congressman(money) 3 4 // Nachricht senden 5 money <- 100 6 } 7 8 9 10 11 12 13 14
- 25. CHANNEL MIT SELECT funcCongressman(money chan int) { select { case amount := <-money: fmt.Println("Received", amount, "$!") } } func main() { 1 money := make(chan int) 2 go Congressman(money) 3 4 // Nachricht senden 5 money <- 100 6 } 7 8 9 10 11 12 13 14
- 26. CHANNELMIT TIMEOUT case <-time.After(1* time.Second): fmt.Println("Got nothing ...!") func main() { 1 money := make(chan int) 2 go Congressman(money) 3 4 time.Sleep(2 * time.Second) 5 } 6 7 func Congressman(money chan int) { 8 select { 9 case amount := <-money: 10 fmt.Println("Received", amount, "$!") 11 12 13 } 14 } 15 time.Sleep(2 * time.Second) func main() { 1 money := make(chan int) 2 go Congressman(money) 3 4 5 } 6 7 func Congressman(money chan int) { 8 select { 9 case amount := <-money: 10 fmt.Println("Received", amount, "$!") 11 case <-time.After(1 * time.Second): 12 fmt.Println("Got nothing ...!") 13 } 14 } 15 time.Sleep(2 * time.Second) select { case amount := <-money: fmt.Println("Received", amount, "$!") case <-time.After(1 * time.Second): fmt.Println("Got nothing ...!") } func main() { 1 money := make(chan int) 2 go Congressman(money) 3 4 5 } 6 7 func Congressman(money chan int) { 8 9 10 11 12 13 14 } 15
- 27. CONCURRENCY mit Goroutinen undChannels
- 28. STANDARDBIBLIOTHEK Tests # HTTP(2) Server undRouter # JSON # Logging #
- 29. EINFACH LANGWEILIG Variablen, Slices, Schleifen Struct # # ZU EINFACH? Struct Embedding Fehler Generics # # # MÄCHTIG Interface Goroutine Channel Standardbibliothe # # # #
- 30.
- 32.