java - 我的 Android 天气应用程序出现奇怪的 "Only the original thread that created a view hierarchy can touch its views."错误

Question

我正在使用以下代码刷新手机显示屏上的天气信息，前 2 - 3 次效果很好，但之后它开始崩溃并给出此错误。

这是代码:

package com.example.ma18uus.myapplication;

import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

import android.widget.TextView;

import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlPullParserFactory;

import java.io.IOException;
import java.io.InputStream;

import java.net.URL;
import java.util.ArrayList;
import java.util.HashMap;


public class weatherView extends AppCompatActivity {


    //Main url
    static final String main_url = "http://api.weatherapi.com/v1/";
    //Live or Weekly forecast
    static final String live_weather = "current.xml?key=";
    //String sevendays_weather = "orecast.xml?key=";
    //API Key + q
    static final String API_Key = "c3bdfadb90d5452bb8003318201801&q=";
    //Location Setters
    static final String location = "London";

    //Complete url for todays forecast
    static final String URLT = main_url + live_weather + API_Key + location;

    //XML node keys
    static final String KEY_ITEM = "root";//parent node
    static final String KEY_NAME = "name";//name of city, string
    static final String KEY_WIND_MPH = "wind_mph";//wind mph, float
    static final String KEY_WIND_KPH = "wind_kph";//wind kph, float
    static final String KEY_C = "temp_c";//Temperature Celsius, int
    static final String KEY_C_FEELS = "feelslike_c";//Temperature feeling Celsius, float
    static final String KEY_F = "temp_f";//Temperature Fahrenheit, int
    static final String KEY_F_FEELS = "feelslike_f";//Temperature feeling Fahrenheit, float
    static final String KEY_HUMIDITY = "humidity";//Humidity Level, int
    static final String KEY_CONDITION_TEXT = "text";//Weather Condition i.e. cloudy, sunny, clear, string


    ArrayList<HashMap<String, String>> menuItems;

    private TextView txt;
    String xml;

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

        menuItems = new ArrayList<HashMap<String, String>>();

        txt = (TextView) findViewById(R.id.weather_window);

        new weatherTask().execute();
       // weatherTask.parseXML();
    }

    private class weatherTask extends AsyncTask<Void, Void, Void>{


        @Override
        protected Void doInBackground(Void... voids) {
            parseXML();
            return null;
        }

        private void parseXML(){


            XmlPullParserFactory parserFactory;
            try {
                parserFactory = XmlPullParserFactory.newInstance();
                XmlPullParser parser = parserFactory.newPullParser();
                try {
                    InputStream is = new URL(URLT).openStream();
                    parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, false);
                    parser.setInput(is, null);

                    processParsing(parser);

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

        }

        private void processParsing(XmlPullParser parser) throws IOException, XmlPullParserException{

            ArrayList<WeatherConditions> weather = new ArrayList<>();
            int eventType = parser.getEventType();
            WeatherConditions currentWeather = null;

            while(eventType != XmlPullParser.END_DOCUMENT){

                String sName = null;

                switch(eventType){
                    case XmlPullParser.START_TAG:
                        sName = parser.getName();

                        if ("root".equals(sName)){
                            currentWeather = new WeatherConditions();
                            weather.add(currentWeather);
                        }else if (currentWeather != null){
                            if ("name".equals(sName)){
                                currentWeather.name = parser.nextText();
                            }
                            else if ("wind_mph".equals(sName)){
                                currentWeather.wind_mph = parser.nextText();
                            }else if ("wind_kph".equals(sName)){
                                currentWeather.wind_kph = parser.nextText();
                            }else if ("temp_c".equals(sName)){
                                currentWeather.celsius = parser.nextText();
                            }else if ("feelsCelsius".equals(sName)){
                                currentWeather.feelsCelsius = parser.nextText();
                            }else if ("fahrenheit".equals(sName)){
                                currentWeather.fahrenheit = parser.nextText();
                            }else if ("feelsFahrenheit".equals(sName)){
                                currentWeather.feelsFahrenheit = parser.nextText();
                            }else if ("humidity".equals(sName)){
                                currentWeather.humidity = parser.nextText();
                            }else if ("text".equals(sName)){
                                currentWeather.condition_text = parser.nextText();
                            }
                        }
                        break;
                }

                eventType = parser.next();
            }

            printWeather(weather);
        }

        private void printWeather(ArrayList<WeatherConditions> weather){

            StringBuilder builder = new StringBuilder();

            for (WeatherConditions weatherC : weather){

                builder.append(weatherC.name).append("\n").append(weatherC.wind_mph).append("\n").append(weatherC.wind_kph).append("\n").append(weatherC.celsius).append("\n").append(weatherC.feelsCelsius).
                        append("\n").append(weatherC.fahrenheit).append("\n").append(weatherC.feelsFahrenheit).append("\n").append(weatherC.humidity).append("\n").append(weatherC.condition_text).append("\n");

            }

            txt.setText(builder.toString());
        }

    }

}

这是错误输出:

01/24 20:06:05: Launching 'app' on Pixel 2 API 29.
$ adb shell am start -n "com.example.ma18uus.myapplication/com.example.ma18uus.myapplication.ClothesApp" -a android.intent.action.MAIN -c android.intent.category.LAUNCHER
Waiting for process to come online...
Connected to process 24573 on device 'emulator-5554'.
Capturing and displaying logcat messages from application. This behavior can be disabled in the "Logcat output" section of the "Debugger" settings page.
I/s.myapplicatio: The ClassLoaderContext is a special shared library.
D/libEGL: Emulator has host GPU support, qemu.gles is set to 1.
W/libc: Unable to set property "qemu.gles" to "1": connection failed; errno=13 (Permission denied)
D/libEGL: loaded /vendor/lib/egl/libEGL_emulation.so
D/libEGL: loaded /vendor/lib/egl/libGLESv1_CM_emulation.so
D/libEGL: loaded /vendor/lib/egl/libGLESv2_emulation.so
W/RenderThread: type=1400 audit(0.0:300): avc: denied { write } for name="property_service" dev="tmpfs" ino=8445 scontext=u:r:untrusted_app_25:s0:c512,c768 tcontext=u:object_r:property_socket:s0 tclass=sock_file permissive=0
W/s.myapplicatio: Accessing hidden method Landroid/view/View;->computeFitSystemWindows(Landroid/graphics/Rect;Landroid/graphics/Rect;)Z (greylist, reflection, allowed)
W/s.myapplicatio: Accessing hidden method Landroid/view/ViewGroup;->makeOptionalFitsSystemWindows()V (greylist, reflection, allowed)
D/HostConnection: HostConnection::get() New Host Connection established 0xdc973e60, tid 24609
D/HostConnection: HostComposition ext ANDROID_EMU_CHECKSUM_HELPER_v1 ANDROID_EMU_native_sync_v2 ANDROID_EMU_native_sync_v3 ANDROID_EMU_native_sync_v4 ANDROID_EMU_dma_v1 ANDROID_EMU_direct_mem ANDROID_EMU_host_composition_v1 ANDROID_EMU_host_composition_v2 ANDROID_EMU_vulkan ANDROID_EMU_deferred_vulkan_commands ANDROID_EMU_vulkan_null_optional_strings ANDROID_EMU_vulkan_create_resources_with_requirements ANDROID_EMU_YUV420_888_to_NV21 ANDROID_EMU_YUV_Cache ANDROID_EMU_async_unmap_buffer GL_OES_EGL_image_external_essl3 GL_OES_vertex_array_object GL_KHR_texture_compression_astc_ldr ANDROID_EMU_gles_max_version_3_0 
W/OpenGLRenderer: Failed to choose config with EGL_SWAP_BEHAVIOR_PRESERVED, retrying without...
D/eglCodecCommon: setVertexArrayObject: set vao to 0 (0) 0 0
D/EGL_emulation: eglCreateContext: 0xe7fbaa20: maj 3 min 0 rcv 3
D/EGL_emulation: eglMakeCurrent: 0xe7fbaa20: ver 3 0 (tinfo 0xe7fe5b10)
W/Gralloc3: mapper 3.x is not supported
D/HostConnection: createUnique: call
    HostConnection::get() New Host Connection established 0xdc975b70, tid 24609
D/HostConnection: HostComposition ext ANDROID_EMU_CHECKSUM_HELPER_v1 ANDROID_EMU_native_sync_v2 ANDROID_EMU_native_sync_v3 ANDROID_EMU_native_sync_v4 ANDROID_EMU_dma_v1 ANDROID_EMU_direct_mem ANDROID_EMU_host_composition_v1 ANDROID_EMU_host_composition_v2 ANDROID_EMU_vulkan ANDROID_EMU_deferred_vulkan_commands ANDROID_EMU_vulkan_null_optional_strings ANDROID_EMU_vulkan_create_resources_with_requirements ANDROID_EMU_YUV420_888_to_NV21 ANDROID_EMU_YUV_Cache ANDROID_EMU_async_unmap_buffer GL_OES_EGL_image_external_essl3 GL_OES_vertex_array_object GL_KHR_texture_compression_astc_ldr ANDROID_EMU_gles_max_version_3_0 
D/eglCodecCommon: allocate: Ask for block of size 0x1000
D/eglCodecCommon: allocate: ioctl allocate returned offset 0x3ff805000 size 0x2000
D/EGL_emulation: eglMakeCurrent: 0xe7fbaa20: ver 3 0 (tinfo 0xe7fe5b10)
D/eglCodecCommon: setVertexArrayObject: set vao to 0 (0) 1 0
W/ActivityThread: handleWindowVisibility: no activity for token android.os.BinderProxy@8f4b1f9
D/NetworkSecurityConfig: Using Network Security Config from resource network_security_config debugBuild: true
D/EGL_emulation: eglMakeCurrent: 0xe7fbaa20: ver 3 0 (tinfo 0xe7fe5b10)
D/EGL_emulation: eglMakeCurrent: 0xe7fbaa20: ver 3 0 (tinfo 0xe7fe5b10)
D/EGL_emulation: eglMakeCurrent: 0xe7fbaa20: ver 3 0 (tinfo 0xe7fe5b10)
E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #1
    Process: com.example.ma18uus.myapplication, PID: 24573
    java.lang.RuntimeException: An error occurred while executing doInBackground()
        at android.os.AsyncTask$4.done(AsyncTask.java:399)
        at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:383)
        at java.util.concurrent.FutureTask.setException(FutureTask.java:252)
        at java.util.concurrent.FutureTask.run(FutureTask.java:271)
        at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:289)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
        at java.lang.Thread.run(Thread.java:919)
     Caused by: android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
        at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:8191)
        at android.view.ViewRootImpl.requestLayout(ViewRootImpl.java:1420)
        at android.view.View.requestLayout(View.java:24454)
        at android.view.View.requestLayout(View.java:24454)
        at android.view.View.requestLayout(View.java:24454)
        at android.view.View.requestLayout(View.java:24454)
        at android.view.View.requestLayout(View.java:24454)
        at android.view.View.requestLayout(View.java:24454)
        at android.widget.RelativeLayout.requestLayout(RelativeLayout.java:380)
        at android.view.View.requestLayout(View.java:24454)
        at android.widget.TextView.checkForRelayout(TextView.java:9681)
        at android.widget.TextView.setText(TextView.java:6269)
        at android.widget.TextView.setText(TextView.java:6097)
        at android.widget.TextView.setText(TextView.java:6049)
        at com.example.ma18uus.myapplication.weatherView$weatherTask.printWeather(weatherView.java:159)
        at com.example.ma18uus.myapplication.weatherView$weatherTask.processParsing(weatherView.java:145)
        at com.example.ma18uus.myapplication.weatherView$weatherTask.parseXML(weatherView.java:89)
        at com.example.ma18uus.myapplication.weatherView$weatherTask.doInBackground(weatherView.java:73)
        at com.example.ma18uus.myapplication.weatherView$weatherTask.doInBackground(weatherView.java:68)
        at android.os.AsyncTask$3.call(AsyncTask.java:378)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:289) 
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167) 
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641) 
        at java.lang.Thread.run(Thread.java:919) 
D/EGL_emulation: eglMakeCurrent: 0xe7fbaa20: ver 3 0 (tinfo 0xe7fe5b10)
I/Process: Sending signal. PID: 24573 SIG: 9
Process 24573 terminated.

第一次工作正常，然后我将 celsius 更改为 temp_c，这是 XML 文件中的名称，仍然工作正常。然后，我将 feelsCelsius 更改为 feelslike_c(这是 XML 文件中的名称)，崩溃开始发生，甚至在将代码恢复到原始状态后仍然持续发生。我也尝试卸载并重新安装该应用程序，但没有任何效果。

Answer 1

AsyncTask 在非 UI 后台线程中执行 doInBackground()。它无法与 UI 交互。另一方面，onPostExecute 方法在主线程中运行时允许触摸 UI。因此，重构您的 AsyncTask 以获得结果:

    private class weatherTask extends AsyncTask<Void, Void, String> { // has result now
        @Override
        protected Void doInBackground(Void... voids) {

            XmlPullParserFactory parserFactory;
            try {
                parserFactory = XmlPullParserFactory.newInstance();
                XmlPullParser parser = parserFactory.newPullParser();
                try {
                    InputStream is = new URL(URLT).openStream();
                    parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, false);
                    parser.setInput(is, null);

                    return processParsing(parser);

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

        }

        private String processParsing(XmlPullParser parser) throws IOException, XmlPullParserException{

            ArrayList<WeatherConditions> weather = new ArrayList<>();
            int eventType = parser.getEventType();
            WeatherConditions currentWeather = null;

            while(eventType != XmlPullParser.END_DOCUMENT){

                String sName = null;

                switch(eventType){
                    case XmlPullParser.START_TAG:
                        sName = parser.getName();

                        if ("root".equals(sName)){
                            currentWeather = new WeatherConditions();
                            weather.add(currentWeather);
                        }else if (currentWeather != null){
                            if ("name".equals(sName)){
                                currentWeather.name = parser.nextText();
                            }
                            else if ("wind_mph".equals(sName)){
                                currentWeather.wind_mph = parser.nextText();
                            }else if ("wind_kph".equals(sName)){
                                currentWeather.wind_kph = parser.nextText();
                            }else if ("temp_c".equals(sName)){
                                currentWeather.celsius = parser.nextText();
                            }else if ("feelsCelsius".equals(sName)){
                                currentWeather.feelsCelsius = parser.nextText();
                            }else if ("fahrenheit".equals(sName)){
                                currentWeather.fahrenheit = parser.nextText();
                            }else if ("feelsFahrenheit".equals(sName)){
                                currentWeather.feelsFahrenheit = parser.nextText();
                            }else if ("humidity".equals(sName)){
                                currentWeather.humidity = parser.nextText();
                            }else if ("text".equals(sName)){
                                currentWeather.condition_text = parser.nextText();
                            }
                        }
                        break;
                }

                eventType = parser.next();
            }

            return printWeather(weather);
        }

        private String printWeather(ArrayList<WeatherConditions> weather){

            StringBuilder builder = new StringBuilder();

            for (WeatherConditions weatherC : weather){

                builder.append(weatherC.name).append("\n").append(weatherC.wind_mph).append("\n").append(weatherC.wind_kph).append("\n").append(weatherC.celsius).append("\n").append(weatherC.feelsCelsius).
                        append("\n").append(weatherC.fahrenheit).append("\n").append(weatherC.feelsFahrenheit).append("\n").append(weatherC.humidity).append("\n").append(weatherC.condition_text).append("\n");

            }

            return builder.toString();
        }


        /// THIS METHOD ADDED
        @Override
        protected void onPostExecute(String result) {
            txt.setText(result);
        }
}