Importing Code, Part 2

Import Statements

Some built-in Scala types and functions are automatically available to you
- List, Vector, Seq, Map, Set, String, Int, Double, Boolean, println (and more)
These work because these three packages are implicitly imported for you:

java.lang.*
scala.*
scala.Predef.*

Everything else is NOT automatically available:

mutable collections
every third-party library

In this video I show several ways to use Scala import statements.

To use a third-party library

Configure how to access/download it in your build tool (such as by adding the correct entry in build.sbt when using the SBT build tool)
- (This code is said to be “packaged” so you can use it)
Then import it into your code with the correct import statement

Example usage

My “utilities” library looks like this:

package com.alvinalexander.utils

object StringUtils:

    // convert "big belly burger" to "Big Belly Burger"
    def capitalizeAllWords(s: String): String =
        s.split(" ")
         .map(_.capitalize)
         .mkString(" ")

    def isBlank(s: String): Boolean =
        s.trim == ""

    def isNullOrEmpty(s: String): Boolean = 
        if s == null || isBlank(s) then true else false
    
    // this code goes on for a while ...

I don’t demonstrate how to configure it in build.sbt, but I show several ways to import it in other code:

package foo

import com.alvinalexander.utils.StringUtils.capitalizeAllWords
import com.alvinalexander.utils.StringUtils.truncate
import com.alvinalexander.utils.StringUtils.truncateWithEllipsis

@main def stringUtilsTest(): Unit =

    val bbb = "big belly burger"

    val capWords = capitalizeAllWords(bbb)
    println(capWords)

    println(truncate(bbb, 9))
    println(truncateWithEllipsis(bbb, 9))

Import Statements

To use a third-party library

Example usage

books by alvin