Android. OS. NetworkOnMainThreadException

When I made a weather forecast widget, I referred to a source code, but always reported an error. I just pulled out the weather code from it and tried to get it. The result was always an error.

 

This is the exception. android. OS. NetworkOnMainThreadException

The Code is as follows:

MainActivity:

public class MainActivity extends Activity {MyWeather myWeather;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);myWeather = new MyWeather();System.out.println(myWeather.getCity());}}

MyWeather:

public class MyWeather {public String city;public String temp1;public String weather1;public String img1;public MyWeather(){getWeather();}public void getWeather(){try {URL url = new URL("http://m.weather.com.cn/data/101250101.html");InputStream is = url.openStream();int len = -1;byte[] buffer = new byte[1024];ByteArrayOutputStream bos = new ByteArrayOutputStream();while ((len = is.read(buffer)) != -1) {bos.write(buffer, 0, len);}String info = bos.toString("utf-8");JSONObject dataJson = new JSONObject(info);JSONObject json = dataJson.getJSONObject("weatherinfo");city = json.getString("city");temp1 = json.getString("temp1");weather1 = json.getString("weather1");img1 = json.getString("img1");bos.close();is.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}catch (JSONException e) {// TODO: handle exception}}public String getCity() {return city;}public void setCity(String city) {this.city = city;}public String getTemp1() {return temp1;}public void setTemp1(String temp1) {this.temp1 = temp1;}public String getWeather1() {return weather1;}public void setWeather1(String weather1) {this.weather1 = weather1;}public String getImg1() {return img1;}public void setImg1(String img1) {this.img1 = img1;}}

After checking the information, the general error should be like this,

So you can change the MainActivity code to the following, read the weather in the new thread, and load it asynchronously using handler:

public class MainActivity extends Activity {MyWeather myWeather;private Handler handler = new Handler() {public void handleMessage(Message msg) {switch (msg.what) {case 0:System.out.println("jason.com" + myWeather.getCity());break;}};};@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);new Thread() {@Overridepublic void run() {// TODO Auto-generated method stubsuper.run();myWeather = new MyWeather();Message msg = handler.obtainMessage();msg.what = 0;handler.sendMessage(msg);}}.start();}}