Merge pull request #1551 from yadavan88/collapse-spaces

Collapse multiple spaces in a string

scala-core-modules/scala-strings-2/src/main/scala/com/baeldung/scala/strings/removemultispace/RemoveMultipleSpaces.scala

@@ -0,0 +1,34 @@
+package com.baeldung.scala.strings.removemultispace
+
+object RemoveMultipleSpaces {
+  def usingReplaceAll(str: String): String = {
+    str.trim.replaceAll("\\s+", " ")
+  }
+
+  def usingSplit(str: String): String = {
+    str.trim.split("\\s+").mkString(" ")
+  }
+
+  def usingZip(str: String): String = {
+    if (str.trim.isEmpty) {
+      str.trim
+    } else {
+      val zipped = str.trim.zip(str.trim.tail)
+      str.trim.head + zipped.collect {
+        case (a, b) if !(a == ' ' && b == ' ') => b
+      }.mkString
+    }
+  }
+
+  def usingStringBuilder(str: String): String = {
+    val sb = new StringBuilder
+    var lastCharWasSpace = false
+
+    for (c <- str.trim) {
+      if (c != ' ' || !lastCharWasSpace) sb.append(c)
+      lastCharWasSpace = c == ' '
+    }
+    sb.toString
+  }
+
+}

scala-core-modules/scala-strings-2/src/test/scala/com/baeldung/scala/strings/removemultispace/RemoveMultipleSpacesUnitTest.scala

@@ -0,0 +1,39 @@
+package com.baeldung.scala.strings.removemultispace
+
+import org.scalatest.flatspec.AnyFlatSpec
+import org.scalatest.matchers.should.Matchers
+import org.scalatest.prop.TableDrivenPropertyChecks
+
+class RemoveMultipleSpacesUnitTest
+  extends AnyFlatSpec
+  with Matchers
+  with TableDrivenPropertyChecks {
+
+  private val table = Table(
+    ("input string", "expected"),
+    ("  too many    spaces    ", "too many spaces"),
+    ("     ", ""),
+    ("a", "a"),
+    ("a ", "a"),
+    ("", "")
+  )
+
+  private val functions = Seq(
+    ("usingReplaceAll", RemoveMultipleSpaces.usingReplaceAll),
+    ("usingSplit", RemoveMultipleSpaces.usingSplit),
+    ("usingZip", RemoveMultipleSpaces.usingZip),
+    ("usingStringBuilder", RemoveMultipleSpaces.usingStringBuilder)
+  )
+  it should "remove multiple spaces with a single space in the string" in {
+    forAll(table) { (input, expected) =>
+      functions.map { (name, fn) =>
+        withClue(
+          s"Failed for the input string ${input} in the function ${name}"
+        ) {
+          fn(input) shouldBe expected
+        }
+      }
+    }
+  }
+
+}