tamrin 8

2026-06-07 00:25:19 +03:30
parent 9e5c715088
commit daf0dfcb68
5 changed files with 190 additions and 62 deletions
@@ -0,0 +1,124 @@
+## 1 . `start()` vs `run()` :
+
+```
+public class StartVsRun {    
+    static class MyRunnable implements Runnable {    
+        public void run() {    
+            System.out.println("Running in: " + Thread.currentThread().getName()); 
+        }    
+    }    
+    public static void main(String[] args) throws InterruptedException {    
+        Thread t1 = new Thread(new MyRunnable(), "Thread-1");    
+        System.out.println("Calling run()");    
+        t1.run();    
+        Thread.sleep(100);    
+    
+        Thread t2 = new Thread(new MyRunnable(), "Thread-2");    
+        System.out.println("Calling start()");    
+        t2.start();    
+    }  
+}  
+```
+### Questions and Answers:  
+* **What output do you get from the program? Why?**
+    * ```
+      //output:
+      Calling run()
+      Running in : main
+      Calling start()
+      Running in : Thread-2
+      ```
+    *  *When `t1.run()` is called directly, it executes the `run()` method in the current thread (the main thread), just like a normal method call. No new thread is created. Therefore, `Thread.currentThread().getName()` returns `"main"`.*  
+    <br>
+    * *When `t2.start()` is called, it creates a new thread named `"Thread-2"` and the JVM automatically invokes the `run()` method inside that new thread. Hence, `Thread.currentThread().getName()` returns `"Thread-2"`.*  
+    <br> 
+* **What’s the difference in behavior between calling `start()` and `run()`?**  
+    <br>
+    * *Calling `run()` directly just executes the code inside `run()` in the caller's thread – it's not multithreading.*  
+    <br>
+    * *Calling `start()` schedules the thread to run, and the `run()` method will be executed in a separate thread concurrently.*
+
+***
+
+## 2. Daemon Threads :
+```
+public class DaemonExample {    
+    static class DaemonRunnable implements Runnable {    
+        public void run() {    
+            for(int i = 0; i < 20; i++) {    
+                System.out.println("Daemon thread running...");    
+                try {    
+                    Thread.sleep(500);    
+                } catch (InterruptedException e) {    
+                 //[Handling Exception...]  
+                }            
+            }    
+        }    
+    }    
+    public static void main(String[] args) {    
+        Thread thread = new Thread(new DaemonRunnable());    
+        thread.setDaemon(true);    
+        thread.start();    
+        System.out.println("Main thread ends.");    
+    }  
+}  
+```
+### Questions and Answers:  
+
+* **What output do you get from the program? Why?**  
+   * ```
+     //output:
+     Main thread ends.
+     Daemon thread running...
+     Daemon thread running...
+     ...
+     //(less than 20 times)
+      ```
+   * *The main thread prints `"Main thread ends."` and then terminates.*  
+   <br> 
+   * *The other thread is a `daemon thread`. Daemon threads are background threads that do not prevent the JVM from exiting.*  
+   <br>
+   * *When the last non-daemon thread (in this case, only the main thread) finishes, the JVM terminates immediately without waiting for the daemon thread to complete its loop.*  
+   <br>
+   * *Therefore, the daemon thread only gets to print a few lines before the program shuts down. It never reaches 20 iterations.*  
+   <br>  
+* **What happens if you remove thread.setDaemon(true)?**  
+    <br>
+    * *The thread prints 20 times and then the program ends, because the thread is no longer a daemon (it becomes a regular user thread).*
+*  **What are some real-life use cases of daemon threads?**  
+    <br>
+     1. *Background music in a game – While you play, music plays in the background. When you close the game, the music stops immediately. No need to finish the song.*  
+     <br>
+     2. *Auto-save in a text editor – Every few minutes, the program saves your file automatically. If you close the program, it doesn't matter if the auto-save finishes or not. Just stop.*  
+<br>
+
+***
+
+## 3. A shorter way to create threads :  
+```
+public class ThreadDemo {  
+    public static void main(String[] args) {  
+        Thread thread = new Thread(() -> {  
+            System.out.println("Thread is running using a ...!");  
+        });  
+  
+        thread.start();  
+    }  
+}   
+```
+### Questions and Answers:  
+
+* **What output do you get from the program?**  
+  * ```
+    //output:
+    Thread is running using a ...!
+    ```
+* **What is the `() -> { ... }` syntax called?**    
+ <br>
+    * *It is called a Lambda Expression*  
+ <br>
+* **How is this code different from creating a class that extends `Thread` or implements `Runnable`?**  
+ <br>
+   * *Shorter and cleaner code.*
+   * *No need for a separate class or explicit `run()` override.*
+   * *Lambda directly provides the `run()` body.*