Thread.run or Thread.start

客官°小女子只卖身不卖艺 2022-06-02 01:16 209阅读 0赞

**Common Pitfall: Calling run() Instead of start()**

When creating and starting a thread a common mistake is to call the run() method of the Thread instead of start(), like this:

Thread newThread = new Thread(MyRunnable());
    newThread.run();  //should be start();

At first you may not notice anything because the Runnable’s **run()** method is executed like you expected. However, it is NOT executed by the new thread you just created. Instead the **run()** method is executed by the thread that created the thread. In other words, the thread that executed the above two lines of code. To have the **run()** method of the MyRunnable instance called by the new created thread, newThread, you MUST call the **newThread.start()** method.

### 示例： ###

> **TestRunnable.java**

public class TestRunnable implements Runnable { 
        private StopWatch stopWatch;
    
        public TestRunnable() {
            stopWatch = new StopWatch();
        }
    
        @Override
        public void run() {
            stopWatch.start();
            System.out.println("TestRunnable start");
            try {
                Thread.sleep(5000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(String.format("TestRunnable end %s", stopWatch.getTime()));
        }
    }

#### **Thread.start()方法** ####

public class TestRunnableMain {
    
        public static void main(String[] args) {
            System.out.println("TestRunnableMain start");
            TestRunnable testRunnable = new TestRunnable();
            Thread thread = new Thread(testRunnable);
            thread.start();
            System.out.println("TestRunnableMain end");
        }
    }

> **执行结果:**
> 
> TestRunnableMain start  
> TestRunnableMain end  
> TestRunnable start  
> TestRunnable end 5012

#### **Thread.run()方法** ####

public class TestRunnableMain {
    
        public static void main(String[] args) {
            System.out.println("TestRunnableMain start");
            TestRunnable testRunnable = new TestRunnable();
            Thread thread = new Thread(testRunnable);
            thread.run();
            System.out.println("TestRunnableMain end");
        }
    }

> **执行结果:**
> 
> TestRunnableMain start  
> TestRunnable start  
> TestRunnable end 5009  
> TestRunnableMain end

[http://tutorials.jenkov.com/java-concurrency/creating-and-starting-threads.html][http_tutorials.jenkov.com_java-concurrency_creating-and-starting-threads.html]

[http_tutorials.jenkov.com_java-concurrency_creating-and-starting-threads.html]: http://tutorials.jenkov.com/java-concurrency/creating-and-starting-threads.html