Key-Value Data in Go
Go's built-in map type is a performant, flexible, and idiomatic way of storing key-value data -- kinda like JSON objects or HashMaps in Java! This type will also expand automatically -- thanks to the Go runtime -- in order to fit your data.
package main
import (
"fmt"
)
// NB: Across these examples, we frequently use the built-in `len(something)` function,
// that gives us the number of elements in our array, map, or slice
func main() {
// This is a map in Go, don't rely on it's order, because that's not guaranteed
// NB: `map` will only allow one value per key (definition of a map)
// NB: `map` capacity can be defined on creation via `make` (if used) and then it will be automatically
// scaled by the Go runtime during program execution. If you know the planned size of the map, that
// capacity hint help to improve performance if that's a key concern for you.
colorsMap := map[string]string{
"AliceBlue": "#F0F8FF",
"AntiqueWhite": "#FAEBD7",
"Aqua": "#00FFFF",
"Aquamarine": "#7FFFD4",
// NB: Go requires this trailing comma on the last element when initializing values over multiple lines
"Azure": "#F0FFFF",
}
// Extract a value with the key
fmt.Println("AliceBlue:", colorsMap["AliceBlue"])
// Set a value for a key (if the key already exists, the value will be overwritten,
// if the key doesn't yet exist, then Go will create it for us and scale the map if/as needed)
colorsMap["Beige"] = "#F5F5DC"
// If a key doesn't exist, go will return the default value (based on the value type), in this case
// an empty string ("")
fmt.Println("This key 'Bisque' doesn't exist: ", colorsMap["Bisque"])
// Check whether an element exists
if val, exists := colorsMap["Foobar"]; exists {
// Since 'Foobar' isn't a key in our map, this will never execute
fmt.Println("Foobar is a color? With the hex value:", val)
}
// Remove an element
// NB: delete will actually remove the element from *your* map! (if the key doesn't exist, then this is a no-op)
delete(colorsMap, "Azure")
// NB: maps can be used in `range` for-loops, e.g., `for key, value := range myMap { ... }`,
// just remember that you can't count on the order of the elements!
fmt.Println("colorsMap:", colorsMap)
}
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