Created simple stopwatch.

src/main/java/quantization/utilities/Stopwatch.java

+package quantization.utilities;
+
+import java.time.Duration;
+import java.time.Instant;
+import java.util.ArrayList;
+
+public class Stopwatch {
+
+    private Instant start;
+    private Instant end;
+    Duration elapsed;
+
+    public Stopwatch() {
+    }
+
+    public void start() {
+        start = Instant.now();
+    }
+
+    public void stop() {
+        end = Instant.now();
+        elapsed = Duration.between(start, end);
+    }
+
+    public void restart() {
+        start = Instant.now();
+    }
+
+    public long totalElapsedNanoseconds() {
+        return elapsed.toNanos();
+    }
+
+    public long totalElapsedMilliseconds() {
+        return elapsed.toMillis();
+    }
+
+    public long totalElapsedSeconds() {
+        return elapsed.toSeconds();
+    }
+
+    public String getElapsedTimeString() {
+        return String.format("%dH %dMin %d Sec %d Ms", elapsed.toHoursPart(), elapsed.toMinutesPart(), elapsed.toSecondsPart(), elapsed.toMillisPart());
+    }
+
+    @Override
+    public String toString() {
+        return getElapsedTimeString();
+    }
+}