Add ReverseWordsInString

src/main/java/com/thealgorithms/strings/ReverseWordsInString.java

@@ -0,0 +1,22 @@
+package com.thealgorithms.strings;
+
+import java.util.Arrays;
+import java.util.Collections;
+
+public final class ReverseWordsInString {
+
+    private ReverseWordsInString() {
+    }
+
+    /**
+     * @brief Reverses words in the input string
+     * @param s the input string
+     * @return A string created by reversing the order of the words in{@code s}
+     */
+
+    public static String reverseWordsInString(final String s) {
+        var words = s.trim().split("\\s+");
+        Collections.reverse(Arrays.asList(words));
+        return String.join(" ", words);
+    }
+}

src/test/java/com/thealgorithms/strings/ReverseWordsInStringTest.java

@@ -0,0 +1,23 @@
+package com.thealgorithms.strings;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class ReverseWordsInStringTest {
+
+    @Test
+    public void testCorrectReverseWordsInTheString() {
+        assertEquals("blue is Sky", ReverseWordsInString.reverseWordsInString("Sky is blue"));
+    }
+
+    @Test
+    public void testCorrectReverseWordsInTheStringWithWhiteSpace() {
+        assertEquals("blue is Sky", ReverseWordsInString.reverseWordsInString("Sky \n is \n \n blue"));
+    }
+
+    @Test
+    public void testReverseWordsInStringForEmpty() {
+        assertEquals("", ReverseWordsInString.reverseWordsInString(""));
+    }
+}