Scala example: String utilities, including left- and right-justifying and padding strings

By Alvin Alexander. Last updated: June 25, 2024

As a little Scala example, here’s a little Scala “string utilities” object that right- and left-justifies strings to a certain string width. Another way to say that is that the strings are left- and right-padded.

Also, the first function adds an ASCII underline to the string it’s given, so it expects a one-line string as input and returns a two-line string as output.

Here’s the source code for these Scala string utilities:

package com.alvinalexander.utils

object StringUtils:

    def addAsciiUnderlineToString(s: String): String =
        val underline = "-" * s.length
        s"$s\n$underline"

    /**
     * Formats the given string so it is right-padded to a string
     * that has the width specified. Ex: Given ("AAPL", 7) as
     * input, it returns "   AAPL".
     * @param s The input string.
     * @param width The desired width. Should be > s.length.
     * @return A left-padded, right-justified string.
     */
    def rightJustify(input: String, width: Int): String =
        String.format(s"%${width}s", input)

    /**
     * Formats the given string so it is left-padded to a string
     * that has the width specified. Ex: Given ("AAPL", 7) as
     * input, it returns "AAPL   ".
     *
     * @param s The input string.
     * @param width The desired width. Should be > s.length.
     * @return A right-padded, left-justified string.
     *
     * Note that the 'f' interpolator does not work in this case:
     *     f"$input%${width}s"
     */
    def leftJustify(input: String, width: Int): String =
        String.format(s"%-${width}s", input)

I’ll try to write more about these over time, but for now I’m just sharing that Scala source code.

scala

ascii