[BAEL-7632] Convert a phone number in words to number with Java (#16248)

* [BAEL-7632] Convert a phone number in words to number with Java

* Updated [BAEL-7632] Convert a phone number in words to number with Java

* Updated [BAEL-7632] Convert a phone number in words to number with Java

core-java-modules/core-java-numbers-7/src/main/java/com/baeldung/convertphonenumberinwordstonumber/UseHashMapToConvertPhoneNumberInWordsToNumber.java

@@ -0,0 +1,43 @@
+import java.util.Map;
+
+public class UseHashMapToConvertPhoneNumberInWordsToNumber {
+    private static Map<String, Integer> multipliers = Map.of("double",2,
+            "triple", 3,
+            "quadruple", 4);
+    private static Map<String, String> digits = Map.of("zero","1",
+            "one", "1",
+            "two", "2",
+            "three", "3",
+            "four", "4",
+            "five", "5",
+            "six", "6",
+            "seven", "7",
+            "eight", "8",
+            "nine", "9");
+
+
+    public static String convertPhoneNumberInWordsToNumber(String phoneNumberInWord) {
+
+        StringBuilder output = new StringBuilder();
+        Integer currentMultiplier = null;
+        String[] words = phoneNumberInWord.split(" ");
+
+        for (String word : words) {
+            Integer multiplier = multipliers.get(word);
+            if (multiplier != null) {
+                if (currentMultiplier != null) {
+                    throw new IllegalArgumentException("Cannot have consecutive multipliers, at: " + word);
+                }
+                currentMultiplier = multiplier;
+            } else {
+                String digit = digits.get(word);
+                if (digit == null) {
+                    throw new IllegalArgumentException("Invalid word: " + word);
+                }
+                output.append(digit.repeat(currentMultiplier != null ? currentMultiplier : 1));
+                currentMultiplier = null;
+            }
+        }
+        return output.toString();
+    }
+}

core-java-modules/core-java-numbers-7/src/main/java/com/baeldung/convertphonenumberinwordstonumber/UseSwitchToConvertPhoneNumberInWordsToNumber.java

@@ -0,0 +1,64 @@
+public class UseSwitchToConvertPhoneNumberInWordsToNumber {
+
+    public static String convertPhoneNumberInWordsToNumber(String phoneNumberInWord) {
+
+        StringBuilder output = new StringBuilder();
+        Integer currentMultiplier = null;
+        String[] words = phoneNumberInWord.split(" ");
+
+        for (String word : words) {
+            Integer multiplier = getWordAsMultiplier(word);
+            if (multiplier != null) {
+                if (currentMultiplier != null) {
+                    throw new IllegalArgumentException("Cannot have consecutive multipliers, at: " + word);
+                }
+                currentMultiplier = multiplier;
+            } else {
+                output.append(getWordAsDigit(word).repeat(currentMultiplier != null ? currentMultiplier : 1));
+                currentMultiplier = null;
+            }
+        }
+        return output.toString();
+    }
+
+    public static Integer getWordAsMultiplier(String word) {
+        switch (word) {
+            case "double":
+                return 2;
+            case "triple":
+                return 3;
+            case "quadruple":
+                return 4;
+            default:
+                return null;
+        }
+    }
+
+    public static String getWordAsDigit(String word) {
+        switch (word) {
+            case "zero":
+                return "0";
+            case "one":
+                return "1";
+            case "two":
+                return "2";
+            case "three":
+                return "3";
+            case "four":
+                return "4";
+            case "five":
+                return "5";
+            case "six":
+                return "6";
+            case "seven":
+                return "7";
+            case "eight":
+                return "8";
+            case "nine":
+                return "9";
+            default:
+                throw new IllegalArgumentException("Invalid word: " + word);
+        }
+    }
+
+}

core-java-modules/core-java-numbers-7/src/test/java/com/baeldung/convertphonenumberinwordstonumber/UseHashMapToConvertPhoneNumberInWordsToNumberUnitTest.java

@@ -0,0 +1,31 @@
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+class UseHashMapToConvertPhoneNumberInWordsToNumberUnitTest {
+
+    @Test
+    void givenStringWithWhiteSpaces_WhenConvertPhoneNumberInWordsToNumber_ThenEquivalentNumber() {
+
+        assertEquals("5248888",
+                UseHashMapToConvertPhoneNumberInWordsToNumber
+                        .convertPhoneNumberInWordsToNumber("five two four quadruple eight"));
+    }
+
+    @Test
+    void givenStringEndingWithConseutiveMultipliers_WhenConvertPhoneNumberInWordsToNumber_ThenThrowException() {
+
+        assertThrows(IllegalArgumentException.class, () -> {
+            UseHashMapToConvertPhoneNumberInWordsToNumber
+                    .convertPhoneNumberInWordsToNumber("five eight three double triple");
+        });
+    }
+
+    @Test
+    void givenStringWithInvalidWords_WhenConvertPhoneNumberInWordsToNumber_ThenThrowException() {
+
+        assertThrows(IllegalArgumentException.class, () -> {
+            UseHashMapToConvertPhoneNumberInWordsToNumber
+                    .convertPhoneNumberInWordsToNumber("five eight three two four penta null eight");
+        });
+    }
+}

core-java-modules/core-java-numbers-7/src/test/java/com/baeldung/convertphonenumberinwordstonumber/UseSwitchToConvertPhoneNumberInWordsToNumberUnitTest.java

@@ -0,0 +1,62 @@
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class UseSwitchToConvertPhoneNumberInWordsToNumberUnitTest {
+
+    @Test
+    void givenStringWithWhiteSpaces_WhenConvertPhoneNumberInWordsToNumber_ThenEquivalentNumber() {
+
+        assertEquals("5248888",
+                UseSwitchToConvertPhoneNumberInWordsToNumber
+                        .convertPhoneNumberInWordsToNumber("five two four quadruple eight"));
+
+    }
+
+    @Test
+    void givenStringEndingWithConseutiveMultipliers_WhenConvertPhoneNumberInWordsToNumber_ThenThrowException() {
+
+        assertThrows(IllegalArgumentException.class, () -> {
+            UseSwitchToConvertPhoneNumberInWordsToNumber
+                    .convertPhoneNumberInWordsToNumber("five eight three double triple");
+        });
+    }
+
+    @Test
+    void givenStringWithInvalidWords_WhenConvertPhoneNumberInWordsToNumber_ThenThrowException() {
+
+        assertThrows(IllegalArgumentException.class, () -> {
+            UseSwitchToConvertPhoneNumberInWordsToNumber
+                    .convertPhoneNumberInWordsToNumber("five eight three two four penta null eight");
+        });
+    }
+
+
+    @Test
+    void givenString_WhenGetWordAsMultiplier_ThenEquivalentNumber() {
+        assertEquals(2, UseSwitchToConvertPhoneNumberInWordsToNumber
+                .getWordAsMultiplier("double"));
+    }
+
+    @Test
+    void givenInvalidString_WhenGetWordAsMultiplier_ThenReturnNull() {
+        assertEquals(null, UseSwitchToConvertPhoneNumberInWordsToNumber
+                .getWordAsMultiplier("hexa"));
+
+    }
+
+    @Test
+    void givenString_WhenMapIndividualDigits_ThenEquivalentNumber() {
+        assertEquals("5",
+                UseSwitchToConvertPhoneNumberInWordsToNumber
+                        .getWordAsDigit("five"));
+    }
+
+    @Test
+    void givenInvalidString_WhenMapIndividualDigits_ThenThrowException() {
+        assertThrows(IllegalArgumentException.class, () -> {
+            UseSwitchToConvertPhoneNumberInWordsToNumber
+                    .convertPhoneNumberInWordsToNumber("penta");
+        });
+    }
+}