本節(jié)有且僅有一個目的妻顶，那就是讓Go程序遇到“panic”。
1.數(shù)組/切片索引越界
func main() {
names := []string{
"煎魚",
"eddycjy",
"Go編程之旅",
} name := names[len(names)]
fmt.Printf("name: %s", name)
}
運行結果：
panic: runtime error: index out of range [3] with length 3
goroutine 1 [running]:
main.main()? ? ? ? /Users/eddycjy/go-application/awesomePanic/main.go:11 +0x1b
2. 空指針調用
type User struct {
Name string
}func (u *User) GetName() string {
return u.Name
}func main() {
s := &User{Name: "煎魚"}
s = nil
s.GetName()}
運行結果：
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x1056f62]
goroutine 1 [running]:
main.(*User).GetName(...)? ? ? ? /Users/eddycjy/go-application/awesomePanic/main.go:8
main.main()? ? ? ? /Users/eddycjy/go-application/awesomePanic/main.go:14 +0x2
3.過早關閉HTTP響應體
func main() {
resp, err := http.Get("https://xxx")
defer resp.Body.Close()
if err != nil {
log.Fatalf("http.Get err: %v", err)
}}
運行結果：
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x40 pc=0x123d4d3]
goroutine 1 [running]:
main.main()? ? ? ? /Users/eddycjy/go-application/awesomePanic/main.go:10 +0x63
4.除以零
func divide(a, b int) int {
return a / b
}func main() {
divide(1, 0)
}
運行結果：
panic: runtime error: integer divide by zero
goroutine 1 [running]:
main.divide(...)? ? ? ? /Users/eddycjy/go-application/awesomePanic/main.go:4
main.main()? ? ? ? /Users/eddycjy/go-application/awesomePanic/main.go:8 +0x12
5.向已關閉的通道發(fā)送消息
func main() {
ch := make(chan string, 1)
ch <- "煎魚"
close(ch)
ch <- "Go編程之旅"
}
運行結果：
panic: send on closed channel
goroutine 1 [running]:
main.main()? ? ? ? /Users/eddycjy/go-application/awesomePanic/main.go:7 +0x7d
6.重復關閉通道
func main() {
ch := make(chan string, 1)
ch <- "Go編程之旅"
close(ch)
close(ch)
}
運行結果：
panic: close of closed channel
goroutine 1 [running]:
main.main()? ? ? ? /Users/eddycjy/go-application/awesomePanic/main.go:7 +0x71
7. 關閉未初始化的通道
func main() {
var ch chan string
close(ch)
}
運行結果：
panic: close of nil channel
goroutine 1 [running]:
main.main()? ? ? ? /Users/eddycjy/go-application/awesomePanic/main.go:5 +0x2a
8.未初始化map
func main() {
var m map[string]string
m["Go編程之旅"] = "一起用Go做項目"
}
運行結果：
panic: assignment to entry in nil map
goroutine 1 [running]:
main.main()? ? ? ? /Users/eddycjy/go-application/awesomePanic/main.go:5 +0x4b
9.跨協(xié)程的“恐慌”處理
func main() {
go func() {
defer func() {
if err := recover(); err != nil {
log.Fatalf("recover err: %v", err)
} }() handle() }() time.Sleep(time.Second)}func handle() {
go divide(1, 0)
}func divide(a, b int) int {
return a / b
}
運行結果：
panic: runtime error: integer divide by zero
goroutine 17 [running]:
main.divide(0x1, 0x0, 0x0)
? ? ? ? /Users/eddycjy/go-application/awesomePanic/main.go:34 +0x40
created by main.handle
? ? ? ? /Users/eddycjy/go-application/awesomePanic/main.go:30 +0x47
10. sync計數(shù)為負值
func main() {
wg := sync.WaitGroup{}
wg.Add(-1)
wg.Wait()
}
運行結果：
panic: sync: negative WaitGroup counter
goroutine 1 [running]:
sync.(*WaitGroup).Add(0xc000104000, 0xffffffffffffffff)
? ? ? ? /usr/local/Cellar/go/1.14/libexec/src/sync/waitgroup.go:74 +0x139
main.main()? ? ? ? /Users/eddycjy/go-application/awesomePanic/main.go:7 +0x44
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