Josh Cummings suggestions: Package renamed and Benchmark using JMH

core-java-modules/core-java-11/src/test/java/com/baeldung/patternreuse/PatternJava11UnitTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.pattern;
+package com.baeldung.patternreuse;
 
 import org.junit.jupiter.api.Test;
 

core-java-modules/core-java-text/pom.xml

@@ -13,6 +13,19 @@
         <relativePath>../../parent-java</relativePath>
     </parent>
 
+    <dependencies>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-core</artifactId>
+            <version>${jmh-core.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-generator-annprocess</artifactId>
+            <version>${jmh-core.version}</version>
+        </dependency>
+    </dependencies>
+
     <build>
         <finalName>core-java-text</finalName>
         <resources>

core-java-modules/core-java-text/src/main/java/com/baeldung/patternreuse/PatternPerformanceComparison.java

@@ -1,68 +1,88 @@
-package com.baeldung.pattern;
+package com.baeldung.patternreuse;
 
-import java.time.Duration;
+import org.openjdk.jmh.annotations.*;
+import org.openjdk.jmh.runner.RunnerException;
+
+import java.io.IOException;
 import java.time.Instant;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.TimeUnit;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.MILLISECONDS)
+@Fork(value = 1, warmups = 1)
+@Warmup(iterations = 5)
+@State(Scope.Benchmark)
 public class PatternPerformanceComparison {
 
     private static final String PATTERN = "\\d*[02468]";
     private static List<String> values;
 
-    public static void main(String[] args) {
+    private static Matcher matcherFromPreCompiledPattern;
-        loadValues();
+    private static Pattern preCompiledPattern;
 
+    public static void main(String[] args) throws IOException, RunnerException {
+        org.openjdk.jmh.Main.main(args);
+    }
+
+    @Benchmark
+    public void matcherFromPreCompiledPatternResetMatches() {
+        //With pre-compiled pattern and reusing the matcher
+        // 1 Pattern object created
+        // 1 Matcher objects created
+        for (String value : values) {
+            matcherFromPreCompiledPattern.reset(value).matches();
+        }
+    }
+
+    @Benchmark
+    public void preCompiledPatternMatcherMatches() {
+        // With pre-compiled pattern
+        // 1         Pattern object created
+        // 5_000_000 Matcher objects created
+        for (String value : values) {
+            preCompiledPattern.matcher(value).matches();
+        }
+    }
+
+    @Benchmark
+    public void patternCompileMatcherMatches() {
+        // Above approach "Pattern.matches(PATTERN, value)" makes this internally
+        // 5_000_000 Pattern objects created
+        // 5_000_000 Matcher objects created
+        for (String value : values) {
+            Pattern.compile(PATTERN).matcher(value).matches();
+        }
+    }
+
+    @Benchmark
+    public void patternMatches() {
+        // Above approach "value.matches(PATTERN)" makes this internally
+        // 5_000_000 Pattern objects created
+        // 5_000_000 Matcher objects created
+        for (String value : values) {
+            Pattern.matches(PATTERN, value);
+        }
+    }
+
+    @Benchmark
+    public void stringMatchs() {
         // 5_000_000 Pattern objects created
         // 5_000_000 Matcher objects created
         Instant start = Instant.now();
         for (String value : values) {
             value.matches(PATTERN);
         }
-        System.out.println(Duration.between(start, Instant.now()).toMillis() + "ms -> String.matchs(regex)");
-
-        // Above approach "value.matches(PATTERN)" makes this internally
-        // 5_000_000 Pattern objects created
-        // 5_000_000 Matcher objects created
-        start = Instant.now();
-        for (String value : values) {
-            Pattern.matches(PATTERN, value);
-        }
-        System.out.println(Duration.between(start, Instant.now()).toMillis() + "ms -> Pattern.matches(regex, charSequence)");
-
-        // Above approach "Pattern.matches(PATTERN, value)" makes this internally
-        // 5_000_000 Pattern objects created
-        // 5_000_000 Matcher objects created
-        start = Instant.now();
-        for (String value : values) {
-            Pattern.compile(PATTERN).matcher(value).matches();
-        }
-        System.out.println(Duration.between(start, Instant.now()).toMillis() + "ms -> Pattern.compile(regex).matcher(charSequence).matches()");
-
-        // With pre-compiled pattern
-        // 1         Pattern object created
-        // 5_000_000 Matcher objects created
-        Pattern preCompiledPattern = Pattern.compile(PATTERN);
-        start = Instant.now();
-        for (String value : values) {
-            preCompiledPattern.matcher(value).matches();
-        }
-        System.out.println(Duration.between(start, Instant.now()).toMillis() + "ms  -> preCompiledPattern.matcher(value).matches()");
-
-        //With pre-compiled pattern and reusing the matcher
-        // 1 Pattern object created
-        // 1 Matcher objects created
-        Matcher matcherFromPreCompiledPattern = preCompiledPattern.matcher("");
-        start = Instant.now();
-        for (String value : values) {
-            matcherFromPreCompiledPattern.reset(value).matches();
-        }
-        System.out.println(Duration.between(start, Instant.now()).toMillis() + "ms  -> matcherFromPreCompiledPattern.reset(value).matches()");
     }
 
-    private static void loadValues() {
+    @Setup()
+    public void setUp() {
+        preCompiledPattern = Pattern.compile(PATTERN);
+        matcherFromPreCompiledPattern = preCompiledPattern.matcher("");
+
         values = new ArrayList<>();
         for (int x = 1; x <= 5_000_000; x++) {
             values.add(String.valueOf(x));

core-java-modules/core-java-text/src/test/java/com/baeldung/patternreuse/PatternUnitTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.pattern;
+package com.baeldung.patternreuse;
 
 import org.junit.jupiter.api.Test;