lambda example (#2480)

log4j2/src/test/java/com/baeldung/logging/log4j2/tests/LambdaExpressionsIntegrationTest.java

@@ -0,0 +1,33 @@
+package com.baeldung.logging.log4j2.tests;
+
+import java.util.Random;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.junit.Test;
+
+public class LambdaExpressionsIntegrationTest {
+
+    private static final Logger logger = LogManager.getRootLogger();
+
+    @Test
+    public void whenCheckLogMessage_thenOk() {
+        if (logger.isTraceEnabled()) {
+            logger.trace("Numer is {}", getRandomNumber());
+        }
+    }
+
+    @Test
+    public void whenUseLambdaExpression_thenOk() {
+        logger.trace("Number is {}", () -> getRandomNumber());
+        logger.trace("Name is {} and age is {}", () -> getName(), () -> getRandomNumber());
+    }
+
+    private int getRandomNumber() {
+        return (new Random()).nextInt(10);
+    }
+
+    private String getName() {
+        return "John";
+    }
+}