add a simple one thread example

Author: fishercoder1534

src/main/java/multithread/OneThreadDemo.java

@@ -0,0 +1,20 @@
+package multithread;
+
+public class OneThreadDemo {
+    static class MeaninglessClass {
+        public void meaninglessMethod() {
+            System.out.println("In meaninglessMethod method now, current thread name is: " + Thread.currentThread().getName());
+        }
+    }
+
+    public static void main(String... args) {
+        /**This is to show that this program will guarantee to run in just one thread: main, there's no multi-threading here.*/
+        MeaninglessClass meaninglessClass = new MeaninglessClass();
+        meaninglessClass.meaninglessMethod();
+        meaninglessClass.meaninglessMethod();
+        meaninglessClass.meaninglessMethod();
+        meaninglessClass.meaninglessMethod();
+        meaninglessClass.meaninglessMethod();
+        System.out.println("Program finished.");
+    }
+}