重置代码：准备采取 AsyncTask 和 Loader 的方案解决问题

Author: windwood-xmu

app/src/main/java/io/github/xmu_android_basics/pm25/MainActivity.java

@@ -33,28 +33,17 @@ protected void onCreate(Bundle savedInstanceState) {
     }
 
     public void onButtonClick(View view) {
-        new Thread(new Runnable() {
-            @Override
-            public void run() {
-                citiesResponse = queryData(PM25_CITIES_REQUEST_URL);
-
-                updateUi(citiesResponse);
-            }
-        }).start();
+        citiesResponse = queryData(PM25_CITIES_REQUEST_URL);
+        updateUi(citiesResponse);
     }
 
     /**
      * Update the screen to display information from the given response.
      */
-    private void updateUi(final String response) {
-        final TextView responseTextView = (TextView) findViewById(R.id.response);
+    private void updateUi(String response) {
+        TextView responseTextView = (TextView) findViewById(R.id.response);
 
-        responseTextView.post(new Runnable() {
-            @Override
-            public void run() {
-                responseTextView.setText(response);
-            }
-        });
+        responseTextView.setText(response);
     }
 
     private String queryData(String queryString) {