php - 安卓 : CalledFromWrongThreadException even when used runOnUIThread

Question

我正在构建一个应用程序，它通过与本地主机中的 php 文件通信来发送登录数据并进行身份验证(引用本教程 http://www.androidhive.info/2012/01/android-login-and-registration-with-php-mysql-and-sqlite/)。我按照教程所说(在主线程中)进行了尝试，但它给出了 NetworkOnMainThreadException。但是，当我在 AsyncTask 中尝试以下操作时，即使我正在使用 runOnUIThread，它也会给出 CalledFromWrongThreadException。

@Override
        protected Void doInBackground(Void... arg0) {

            String username = etUsername.getText().toString();
            String password = etPass.getText().toString();
            UserFunctions userFunctions = new UserFunctions();
            final JSONObject json = userFunctions.loginUser(username, password);

            try {
                if (json.getString(KEY_SUCCESS) != null) {

                    String res = json.getString(KEY_SUCCESS);
                    if (Integer.parseInt(res) == 1) {
                        // user successfully logged in
                        runOnUiThread(new Runnable() {
                            @Override
                            public void run() {
                                errorTxt.setText("");
                                //if (pDialog.isShowing())
                                    //pDialog.dismiss();
                                Intent intent = new Intent(
                                        getApplicationContext(),
                                        AgentHome.class);
                                startActivity(intent);
                            }
                        });

                    }
                } else if(json.getString(KEY_ERROR) != null) {
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            //if (pDialog.isShowing())
                                //pDialog.dismiss();
                            errorTxt.setText("Invalid username or password");
                        }
                    });

                }
            } catch (JSONException e) {
                e.printStackTrace();
            }

            return null;
        }

编辑:我将 errorTxt.setText("") 放在 runOnUIThread 中，但它仍然会出现以下错误

02-11 10:27:20.397: E/AndroidRuntime(4957): FATAL EXCEPTION: AsyncTask #1
02-11 10:27:20.397: E/AndroidRuntime(4957): Process: collector.lbfinance, PID: 4957
02-11 10:27:20.397: E/AndroidRuntime(4957): java.lang.RuntimeException: An error occured while executing doInBackground()
02-11 10:27:20.397: E/AndroidRuntime(4957):     at android.os.AsyncTask$3.done(AsyncTask.java:300)
02-11 10:27:20.397: E/AndroidRuntime(4957):     at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
02-11 10:27:20.397: E/AndroidRuntime(4957):     at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
02-11 10:27:20.397: E/AndroidRuntime(4957):     at java.util.concurrent.FutureTask.run(FutureTask.java:242)
02-11 10:27:20.397: E/AndroidRuntime(4957):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
02-11 10:27:20.397: E/AndroidRuntime(4957):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
02-11 10:27:20.397: E/AndroidRuntime(4957):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
02-11 10:27:20.397: E/AndroidRuntime(4957):     at java.lang.Thread.run(Thread.java:841)
02-11 10:27:20.397: E/AndroidRuntime(4957): Caused by: java.lang.NullPointerException
02-11 10:27:20.397: E/AndroidRuntime(4957):     at collector.lbfinance.MainActivity$GetPassword.doInBackground(MainActivity.java:108)
02-11 10:27:20.397: E/AndroidRuntime(4957):     at collector.lbfinance.MainActivity$GetPassword.doInBackground(MainActivity.java:1)
02-11 10:27:20.397: E/AndroidRuntime(4957):     at android.os.AsyncTask$2.call(AsyncTask.java:288)
02-11 10:27:20.397: E/AndroidRuntime(4957):     at java.util.concurrent.FutureTask.run(FutureTask.java:237)
02-11 10:27:20.397: E/AndroidRuntime(4957):     ... 4 more

Answer 1

errorTxt.setText(""); 不在 ui 线程上。您无法从后台线程更新用户界面。

您还可以在单​​击按钮时从 edittext 中获取文本，并将其作为参数直接传递给 doInBackground。

Asynctask 有 onPreExecute 和 onPostExecute 是在 ui 线程上调用的。您应该考虑在这些方法中更新 ui。在 doInbackground 中完成所有后台计算。我看不到需要 runOnUiThread。