From 7a92909566d22741748d0a9c4303dcfc8af76ed0 Mon Sep 17 00:00:00 2001
From: Yasin <yasin.bhojawala@gmail.com>
Date: Tue, 7 Mar 2017 01:28:33 +0530
Subject: [PATCH] BAEL-608 - Introduction to Java9 StackWalking API (#1315)

* yasin.bhojawala@gmail.com

Evaluation article on Different Types of Bean Injection in Spring

* Revert "yasin.bhojawala@gmail.com"

This reverts commit 963cc51a7a15b75b550108fe4e198cd65a274032.

* Fixing compilation error and removing unused import

* Introduction to Java9 StackWalking API - yasin.bhojawala@gmail.com

Code examples for the article "Introduction to Java9 StackWalking API"
---
 .../java9/stackwalker/StackWalkerDemo.java    | 64 +++++++++++++++++++
 .../stackwalker/StackWalkerDemoTest.java      | 11 ++++
 2 files changed, 75 insertions(+)
 create mode 100644 core-java-9/src/main/java/com/baeldung/java9/stackwalker/StackWalkerDemo.java
 create mode 100644 core-java-9/src/test/java/com/baeldung/java9/stackwalker/StackWalkerDemoTest.java

diff --git a/core-java-9/src/main/java/com/baeldung/java9/stackwalker/StackWalkerDemo.java b/core-java-9/src/main/java/com/baeldung/java9/stackwalker/StackWalkerDemo.java
new file mode 100644
index 0000000000..ee2cf092cd
--- /dev/null
+++ b/core-java-9/src/main/java/com/baeldung/java9/stackwalker/StackWalkerDemo.java
@@ -0,0 +1,64 @@
+package com.baeldung.java9.stackwalker;
+
+import java.lang.StackWalker.StackFrame;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class StackWalkerDemo {
+
+    public void methodOne() {
+        this.methodTwo();
+    }
+
+    public void methodTwo() {
+        this.methodThree();
+    }
+
+    public void methodThree() {
+        List<StackFrame> stackTrace = StackWalker.getInstance(StackWalker.Option.RETAIN_CLASS_REFERENCE)
+            .walk(StackWalkerDemo::walkExample);
+
+        printStackTrace(stackTrace);
+
+        System.out.println("---------------------------------------------");
+
+        stackTrace = StackWalker.getInstance(StackWalker.Option.RETAIN_CLASS_REFERENCE)
+            .walk(StackWalkerDemo::walkExample2);
+
+        printStackTrace(stackTrace);
+
+        System.out.println("---------------------------------------------");
+
+        String line = StackWalker.getInstance()
+            .walk(StackWalkerDemo::walkExample3);
+        System.out.println(line);
+    }
+
+    private static List<StackFrame> walkExample(Stream<StackFrame> stackFrameStream) {
+        return stackFrameStream.collect(Collectors.toList());
+    }
+
+    private static List<StackFrame> walkExample2(Stream<StackFrame> stackFrameStream) {
+        return stackFrameStream.filter(frame -> frame.getClassName()
+            .contains("com.baeldung"))
+            .collect(Collectors.toList());
+    }
+
+    private static String walkExample3(Stream<StackFrame> stackFrameStream) {
+        return stackFrameStream.filter(frame -> frame.getClassName()
+            .contains("com.baeldung")
+            && frame.getClassName()
+                .endsWith("Test"))
+            .findFirst()
+            .map(frame -> frame.getClassName() + "#" + frame.getMethodName() + ", Line " + frame.getLineNumber())
+            .orElse("Unknown caller");
+    }
+
+    private void printStackTrace(List<StackFrame> stackTrace) {
+        for (StackFrame stackFrame : stackTrace) {
+            System.out.println(stackFrame.getDeclaringClass()
+                .toString() + "#" + stackFrame.getMethodName() + ", Line " + stackFrame.getLineNumber());
+        }
+    }
+}
diff --git a/core-java-9/src/test/java/com/baeldung/java9/stackwalker/StackWalkerDemoTest.java b/core-java-9/src/test/java/com/baeldung/java9/stackwalker/StackWalkerDemoTest.java
new file mode 100644
index 0000000000..61c8440b87
--- /dev/null
+++ b/core-java-9/src/test/java/com/baeldung/java9/stackwalker/StackWalkerDemoTest.java
@@ -0,0 +1,11 @@
+package com.baeldung.java9.stackwalker;
+
+import org.junit.Test;
+
+public class StackWalkerDemoTest {
+
+    @Test
+    public void walkTheStack() {
+        new StackWalkerDemo().methodOne();
+    }
+}