Refactor test assertions and streamline code

Switched to using AssertJ's assertThat assertion for improved readability and precision in SumBigDecimalsTest. Suppressing "unused" warning in SumBigDecimals class for unused method.

Significantly refactored the implementation of LoopsSortsAndIfs class. Replaced several for-loops, condition checks, and separate list sorting with a streamlined approach utilizing Java Streams API. This reduces redundancy and improves readability.

src/main/java/refactoring/after/LoopsSortsAndIfs.java

@@ -1,30 +1,16 @@
 package refactoring.after;
 
-import java.util.ArrayList;
-import java.util.Collections;
+import java.util.Arrays;
 import java.util.Comparator;
-import java.util.List;
 
 public class LoopsSortsAndIfs {
     public static void main(String[] args) {
-        String[] strings = "this is an array of strings".split(" ");
 
-        List<String> evenLengths = new ArrayList<>();
-        for (String s : strings) {
-            if (s.length() % 2 == 0) {
-                evenLengths.add(s.toUpperCase());
-            }
-        }
-
-        Collections.sort(evenLengths, new Comparator<String>() {
-            @Override
-            public int compare(String s1, String s2) {
-                return s1.length() - s2.length();
-            }
-        });
-
-        for (String s : evenLengths) {
-            System.out.println(s);
-        }
+        Arrays.stream("this is an array of strings".split(" "))
+                .filter(s -> s.length() % 2 == 0)
+                .map(String::toUpperCase)
+                .sorted(Comparator.comparingInt(String::length)
+                        .thenComparing(Comparator.naturalOrder()))
+                .forEach(System.out::println);
     }
 }

src/main/java/streams/SumBigDecimals.java

@@ -5,6 +5,7 @@
 
 public class SumBigDecimals {
 
+    @SuppressWarnings("unused")
     public BigDecimal sumFirstN_asDoubles(int n) {
         double total = Stream.iterate(BigDecimal.ONE, bd -> bd.add(BigDecimal.ONE))
                 .limit(n)

src/test/java/streams/SumBigDecimalsTest.java

@@ -5,6 +5,8 @@
 
 import java.math.BigDecimal;
 
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.within;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
 public class SumBigDecimalsTest {
@@ -13,7 +15,7 @@ public class SumBigDecimalsTest {
     @Test
     public void sumFirstN_usingReduce() {
         BigDecimal answer = summer.sumFirstN_usingReduce(10);
-        assertEquals(new BigDecimal("55"), answer);
+        assertThat(answer).isCloseTo(BigDecimal.valueOf(55), within(BigDecimal.valueOf(0.01)));
     }
 
     @Test @Disabled("disable until demo")