golang怎么判断数组是否为空

package main

import "fmt"

func main() {

    var arr []string

    if arr == nil {

        fmt.Println("this is null")

    }

    if len(arr) > 0 {

        fmt.Println("len arr > 0")

    }else{

        fmt.Println("len this is null")

    }

    if arr[0] != "" {

        fmt.Println("arr 0 != null")   

    }else{

        fmt.Println("[0] this is null")

    }

}