Android Toast崩溃

Question

我在我的Android应用程序中创建了一个连接到pc服务器的客户端。当我的应用程序连接到服务器时，我希望看到“建立连接”，为此我使用吐司但我的程序在启动时崩溃。这里有代码：

 protected String doInBackground(String... params) {

       try {
             Socket client = new Socket("192.168.1.2", 4444);  //connect to server
             Toast t = Toast.makeText(getApplicationContext(), "Connection established" ,Toast.LENGTH_LONG);
             t.show();
             client.close();   //closing the connection

            } catch (UnknownHostException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();

        }

        return null;
    }

我有这个问题，因为我写了“Toast t = Toast.makeText（getApplicationContext（），”Connection established“，Toast.LENGTH_LONG）;”

这里有logcat：

    05-29 16:28:54.076: E/AndroidRuntime(32436): FATAL EXCEPTION: AsyncTask #1
05-29 16:28:54.076: E/AndroidRuntime(32436): java.lang.RuntimeException: An error occured while executing doInBackground()
05-29 16:28:54.076: E/AndroidRuntime(32436):    at android.os.AsyncTask$3.done(AsyncTask.java:299)
05-29 16:28:54.076: E/AndroidRuntime(32436):    at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
05-29 16:28:54.076: E/AndroidRuntime(32436):    at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
05-29 16:28:54.076: E/AndroidRuntime(32436):    at java.util.concurrent.FutureTask.run(FutureTask.java:239)
05-29 16:28:54.076: E/AndroidRuntime(32436):    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
05-29 16:28:54.076: E/AndroidRuntime(32436):    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
05-29 16:28:54.076: E/AndroidRuntime(32436):    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
05-29 16:28:54.076: E/AndroidRuntime(32436):    at java.lang.Thread.run(Thread.java:841)
05-29 16:28:54.076: E/AndroidRuntime(32436): Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
05-29 16:28:54.076: E/AndroidRuntime(32436):    at android.os.Handler.<init>(Handler.java:197)
05-29 16:28:54.076: E/AndroidRuntime(32436):    at android.os.Handler.<init>(Handler.java:111)
05-29 16:28:54.076: E/AndroidRuntime(32436):    at android.widget.Toast$TN.<init>(Toast.java:324)
05-29 16:28:54.076: E/AndroidRuntime(32436):    at android.widget.Toast.<init>(Toast.java:91)
05-29 16:28:54.076: E/AndroidRuntime(32436):    at android.widget.Toast.makeText(Toast.java:238)
05-29 16:28:54.076: E/AndroidRuntime(32436):    at com.example.social_network.MainActivity$myTask.doInBackground(MainActivity.java:34)
05-29 16:28:54.076: E/AndroidRuntime(32436):    at com.example.social_network.MainActivity$myTask.doInBackground(MainActivity.java:1)
05-29 16:28:54.076: E/AndroidRuntime(32436):    at android.os.AsyncTask$2.call(AsyncTask.java:287)
05-29 16:28:54.076: E/AndroidRuntime(32436):    at java.util.concurrent.FutureTask.run(FutureTask.java:234)
05-29 16:28:54.076: E/AndroidRuntime(32436):    ... 4 more

感谢

Answer 1

当然，您需要使用AsyncTask的最佳实践。例如，检查this post。

但如果你想快速测试一下，试试这个：

替换这些行：

Toast t = Toast.makeText(getApplicationContext(), "Connection established", Toast.LENGTH_LONG);
t.show();

这些：

Handler handler = new Handler(Looper.getMainLooper());
handler.post(new Runnable() {
    public void run() {
        Toast t = Toast.makeText(getApplicationContext(), "Connection established", Toast.LENGTH_LONG);
        t.show();
    }
});

FOR更新代码：

替换此行：

if(result.equalsIgnoreCase("Exception Caught")){

这一个：

if ("Exception Caught".equalsIgnoreCase(result)) {

Answer 2

Toast无法显示在doInBackground()中，因为它与用户界面相关，您无法在doInBackground()中执行与用户界面相关的任务。您可以在onPostExecute()或onPreExecute()。

AsyncTask

Answer 3

看看这个：How to show toast in AsyncTask in doInBackground

你不能在doinbackground中调用Toast。你应该在onPostExecute（）或onProgressUpdate（）中调用它。

感谢codeMagic。