BAEL 1748 - Optional - orElse() vs orElseGet() (#4240)

* Types of Bean Injection in Spring

* Changing config file name

* BAEL-1584 : Find an element in list

* Revert "Changing config file name"

This reverts commit d857db9f65b1cf89773348e3901385ce59d9e1f8.

* Revert "Types of Bean Injection in Spring"

This reverts commit e9efcb8e70f37e7488aa2371bb3ee62c676996f4.

* BAEL-1584 : Find an Element in Given List

* BAEL-1584 : Hashcode impl changed

* BAEL:1584 : ListIterator to Iterator change

* Method name refactoring

* BAEL 1748 - Optional OrElse vs OrElseGet

* BAEL-1748 Benchmark Runner

core-java-8/src/main/java/com/baeldung/optional/OrElseAndOrElseGet.java

@@ -0,0 +1,34 @@
+package com.baeldung.optional;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+import java.util.Random;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class OrElseAndOrElseGet {
+
+    public static List<String> names = Arrays.asList("John", "Jones", "Kelly", "Cristina", "Raven");
+
+    private static final Logger LOG = LoggerFactory.getLogger(OrElseAndOrElseGet.class);
+
+    public String getRandomName() {
+        LOG.info("getRandomName() method - start");
+        Random random = new Random();
+        int index = random.nextInt(5);
+        LOG.info("getRandomName() method - end");
+        return names.get(index);
+    }
+
+    public String getNameUsingOrElse(String name) {
+        return Optional.ofNullable(name)
+            .orElse(getRandomName());
+    }
+
+    public String getNameUsingOrElseGet(String name) {
+        return Optional.ofNullable(name)
+            .orElseGet(() -> getRandomName());
+    }
+}

core-java-8/src/main/java/com/baeldung/optional/OrElseAndOrElseGetBenchmarkRunner.java

@@ -0,0 +1,37 @@
+package com.baeldung.optional;
+
+import java.io.IOException;
+import java.util.concurrent.TimeUnit;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.runner.RunnerException;
+
+@Fork(1)
+@State(Scope.Benchmark)
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.NANOSECONDS)
+public class OrElseAndOrElseGetBenchmarkRunner {
+
+    private OrElseAndOrElseGet orElsevsOrElseGet = new OrElseAndOrElseGet();
+
+    public static void main(String[] args) throws RunnerException, IOException {
+        org.openjdk.jmh.Main.main(args);
+    }
+
+    @Benchmark
+    public String orElseBenchmark() {
+        return orElsevsOrElseGet.getNameUsingOrElse("baeldung");
+    }
+
+    @Benchmark
+    public String orElseGetBenchmark() {
+        return orElsevsOrElseGet.getNameUsingOrElseGet("baeldung");
+    }
+
+}

core-java-8/src/test/java/com/baeldung/java8/optional/OrElseAndOrElseGetTest.java

@@ -0,0 +1,44 @@
+package com.baeldung.java8.optional;
+
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import static org.junit.Assert.*;
+
+import com.baeldung.optional.OrElseAndOrElseGet;
+
+public class OrElseAndOrElseGetTest {
+
+    private OrElseAndOrElseGet orElsevsOrElseGet = new OrElseAndOrElseGet();
+
+    private static final Logger LOG = LoggerFactory.getLogger(OrElseAndOrElseGetTest.class);
+
+    @Test
+    public void givenNonEmptyOptional_whenOrElseUsed_thenGivenStringReturned() {
+        LOG.info("In givenNonEmptyOptional_whenOrElseUsed_thenGivenStringReturned()");
+        String name = orElsevsOrElseGet.getNameUsingOrElse("baeldung");
+        assertEquals(name, "baeldung");
+    }
+
+    @Test
+    public void givenEmptyOptional_whenOrElseUsed_thenRandomStringReturned() {
+        LOG.info("In givenEmptyOptional_whenOrElseUsed_thenRandomStringReturned()");
+        String name = orElsevsOrElseGet.getNameUsingOrElse(null);
+        assertTrue(orElsevsOrElseGet.names.contains(name));
+    }
+
+    @Test
+    public void givenNonEmptyOptional_whenOrElseGetUsed_thenGivenStringReturned() {
+        LOG.info("In givenNonEmptyOptional_whenOrElseGetUsed_thenGivenStringReturned()");
+        String name = orElsevsOrElseGet.getNameUsingOrElseGet("baeldung");
+        assertEquals(name, "baeldung");
+    }
+
+    @Test
+    public void givenEmptyOptional_whenOrElseGetUsed_thenRandomStringReturned() {
+        LOG.info("In givenEmptyOptional_whenOrElseGetUsed_thenRandomStringReturned()");
+        String name = orElsevsOrElseGet.getNameUsingOrElseGet(null);
+        assertTrue(orElsevsOrElseGet.names.contains(name));
+    }
+}