BAEL-6185 reuse string builder performance (#13791)

core-java-modules/core-java-strings/src/main/java/com/baeldung/stringbuilder/ReuseStringBuilderPerformance.java

@@ -0,0 +1,55 @@
+package com.baeldung.stringbuilder;
+
+import org.openjdk.jmh.annotations.*;
+import org.openjdk.jmh.runner.Runner;
+import org.openjdk.jmh.runner.options.Options;
+import org.openjdk.jmh.runner.options.OptionsBuilder;
+
+import java.util.concurrent.TimeUnit;
+
+@BenchmarkMode(Mode.SingleShotTime)
+@OutputTimeUnit(TimeUnit.MILLISECONDS)
+@Measurement(batchSize = 100000, iterations = 10)
+@Warmup(batchSize = 100000, iterations = 10)
+@State(Scope.Thread)
+public class ReuseStringBuilderPerformance {
+
+    @Benchmark
+    public void benchmarkStringBuilder() {
+        for (int i = 0; i < 100; i++) {
+            StringBuilder stringBuilder = new StringBuilder();
+            stringBuilder.append("baeldung");
+            stringBuilder.toString();
+        }
+    }
+
+    @Benchmark
+    public void benchmarkStringBuilderReuseWithSetLength() {
+        StringBuilder stringBuilder = new StringBuilder();
+        for (int i = 0; i < 100; i++) {
+            stringBuilder.append("baeldung");
+            stringBuilder.toString();
+            stringBuilder.setLength(0);
+        }
+    }
+
+    @Benchmark()
+    public void benchmarkStringBuilderReuseWithDelete() {
+        StringBuilder stringBuilder = new StringBuilder();
+        for (int i = 0; i < 100; i++) {
+            stringBuilder.append("baeldung");
+            stringBuilder.toString();
+            stringBuilder.delete(0, stringBuilder.length());
+        }
+    }
+
+    public static void main(String[] args) throws Exception {
+        Options options = new OptionsBuilder()
+                .include(ReuseStringBuilderPerformance.class.getSimpleName()).threads(1)
+                .forks(1).shouldFailOnError(true)
+                .shouldDoGC(true)
+                .jvmArgs("-server").build();
+        new Runner(options).run();
+    }
+
+}