Add files via upload

Author: wagnerjfr

ThreadLocalDemo.java

@@ -0,0 +1,68 @@
+package thread;
+
+import java.util.concurrent.ThreadLocalRandom;
+
+/**
+ * In this example, 3 threads will print the 3 consecutive exponential values of 1, 2 and 3.
+ * All of them will be using the SharedUtil class for it.
+ * P.S. SharedUtil uses Java ThreadLocal class which enables us to create variables that can only be read and written by the same thread.
+ */
+public class ThreadLocalDemo {
+
+    public static void main(String[] args) {
+
+        new ThreadLocalDemo().execute();
+
+    }
+
+    private void execute() {
+        for (int i = 1; i <= 3; i++) {
+            new Thread(new Task(i), "Thread exp" + i).start();
+        }
+    }
+
+    private class Task implements Runnable {
+
+        private int num;
+
+        Task(int num) {
+            this.num = num;
+        }
+
+        @Override
+        public void run() {
+            try {
+                SharedUtil.setCounter(num);
+
+                for (int i = 0; i < 3; i++) {
+                    SharedUtil.calculateAndPrint();
+                    Thread.sleep(ThreadLocalRandom.current().nextInt(100, 500));
+                }
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            } finally {
+                SharedUtil.remove();
+            }
+        }
+    }
+
+    private static class SharedUtil {
+        private static ThreadLocal<Integer> threadLocalCounter = ThreadLocal.withInitial(() -> 0);
+        private static ThreadLocal<Integer> threadLocalAccumulator = ThreadLocal.withInitial(() -> 0);
+
+        static void setCounter(int number) {
+            threadLocalCounter.set(number);
+            threadLocalAccumulator.set(number);
+        }
+
+        static void calculateAndPrint() {
+            System.out.println(Thread.currentThread().getName() + ": " + threadLocalAccumulator.get());
+            threadLocalAccumulator.set(threadLocalAccumulator.get() * threadLocalCounter.get());
+        }
+
+        static void remove() {
+            threadLocalAccumulator.remove();
+            threadLocalCounter.remove();
+        }
+    }
+}