android 无法在未调用 Looper.prepare 的线程内创建处理程序

Question

尝试使用线程时出现此错误。

无法在尚未调用 Looper.prepare() 的线程内创建处理程序

    Thread anOpenConnectionThread = new Thread(new Runnable()
    {
        @Override
        public void run()
        {

            try
            {
                openConnection();
            }
            catch (Exception err)
            {
                  runOnUiThread(new Runnable() {
                      public void run() {

                          Toast.makeText(LaunchApp.this, "Opening connection with " + ip + " failed!", Toast.LENGTH_SHORT).show();
                     }
                 });

                EneterTrace.error("Open connection failed.", err);
            }
        }
    });

在onCreate中启动线程:

anOpenConnectionThread.start(); 

以防万一的打开连接代码:

private void openConnection() throws Exception
{
    // Create sender sending MyRequest and as a response receiving MyResponse
    IDuplexTypedMessagesFactory aSenderFactory = new DuplexTypedMessagesFactory();
    mySender = aSenderFactory.createDuplexTypedMessageSender(MyResponse.class, MyRequest.class);

    // Subscribe to receive response messages.
    mySender.responseReceived().subscribe(myOnResponseHandler);

    // Create TCP messaging for the communication.
    ip = sProfile.getIp();
    IMessagingSystemFactory aMessaging = new TcpMessagingSystemFactory();
    IDuplexOutputChannel anOutputChannel
        = aMessaging.createDuplexOutputChannel("tcp://" + ip + ":8060/");
    Toast.makeText(this, ip, Toast.LENGTH_SHORT).show();

    // Attach the output channel to the sender and be able to send
    // messages and receive responses.
    mySender.attachDuplexOutputChannel(anOutputChannel);
}

sProfile 已初始化!这是设置 ip 的地方(它在 toast 中显示了 ip，所以我 100% 确定它不为空)

        @Override
        public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) {
            int pos = profileSpinner.getSelectedItemPosition() + 1;
            currentIp = myDb.getIp(pos);
            Toast.makeText(SelectProfile.this, currentIp, Toast.LENGTH_SHORT).show();
        }

getIp 正在返回那里设置的 ip。

public String getIp()
{
    return currentIp;
}

Answer 1

在线程的运行方法中，您有 openConnection()。在 openConnection() 中，您有以下内容

   Toast.makeText(this, ip, Toast.LENGTH_SHORT).show();

无法从线程更新 ui。