Summary - Advanced strings

Combine Regex, StringBuilder and trim to write a CSV parser.

Summary - Advanced strings

In this group you learned regular expressions, matching with matches and find, transforming with replace, efficient joining with StringBuilder and edge shaping with trim/padStart.

Now it is time to combine them in a single task: find the digits in a text, trim the spaces and print the result. This is a small sample of a real text-processing pipeline.

Exercise Clean text and replace digits

First trim the string " a1b22 " to remove edge spaces. Then replace the digits with Regex("\\d+") using "#" and print.

Show example solution

val r = Regex("\\d+")
println("  a1b22  ".trim().replace(r, "#"))

Test yourself

Match tool to purpose

Regex

Pattern match
find

First match
replace

Substitute
trim

Edge cleanup

Fill in the blank: builder to string

val sb = StringBuilder("hi")
val s = sb.____()

Show answer

val sb = StringBuilder("hi")
val s = sb.toString()

You concatenate 500 times in a loop. Which is best?
- StringBuilder
- Regex
- String +
- trim
Show answer

StringBuilder — Is StringBuilder; it does not create a new object per append.

Next lesson: enum class

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