为什么我的代码在主线程上运行？

Question

我在onCreate方法中使用以下代码：

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Button button = (Button) findViewById(R.id.button1);
        button.setOnClickListener(new OnClickListener() {


            @Override
            public void onClick(View arg0) {
                Thread thread = new Thread(new Runnable() {

                    @Override
                    public void run() {
                        try {
                            ServerSocket serverSocket = new ServerSocket(9002);
                            Socket s = serverSocket.accept();

                            DataOutputStream outputStream = new DataOutputStream(
                                    s.getOutputStream());
                            BufferedReader inputStream = new BufferedReader(
                                    new InputStreamReader(s.getInputStream()));

                            outputStream.write("Howdy! newbie".getBytes());

                            s.close();

                        } catch (IOException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                    }
                });
                thread.run();
            }
        });
    }

它给了我一个NetworkOnMainThreadException！

当我使用以下行删除限制时，它确实有效：

StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
            StrictMode.setThreadPolicy(policy); 

但我为什么要用呢？

我使用了线程，为什么它不在分离的线程上运行并在UI线程上运行？！

Answer 1

更改

thread.run();

到

thread.start();

<强>差：

  

Thread.run（）不会产生新线程，而 Thread.start（）   是的，即Thread.run实际上运行在与...相同的线程上   调用者而Thread.start()创建一个新任务的线程   跑了。

有关详细信息，请参阅Difference between running and starting a thread

Answer 2

因为你没有要求线程启动。

替换：

thread.run();

用

thread.start();

调用run()只会在当前线程上执行提供的Runnable。但是，start()会将执行产生到新线程上。

Answer 3

从thread.run()更改为thread.start()

---

  @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);

            Button button = (Button) findViewById(R.id.button1);
            button.setOnClickListener(new OnClickListener() {


                @Override
                public void onClick(View arg0) {
                    Thread thread = new Thread(new Runnable() {

                        @Override
                        public void run() {
                            try {
                                ServerSocket serverSocket = new ServerSocket(9002);
                                Socket s = serverSocket.accept();

                                DataOutputStream outputStream = new DataOutputStream(
                                        s.getOutputStream());
                                BufferedReader inputStream = new BufferedReader(
                                        new InputStreamReader(s.getInputStream()));

                                outputStream.write("Howdy! newbie".getBytes());

                                s.close();

                            } catch (IOException e) {
                                // TODO Auto-generated catch block
                                e.printStackTrace();
                            }
                        }
                    });
                    thread.start();
                }
            });
        }