Question

textview没有显示我需要的值。我正在尝试在其中显示天气预报。但是，当我尝试这样做时，该应用程序根本不显示任何内容。

<TextView
    android:id="@+id/degree"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Loading..."
    android:textSize="60sp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

下来是我的主要活动java类

public class MainActivity extends AppCompatActivity {

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

    TextView tv = findViewById(R.id.degree);

    WeatherTask task = new WeatherTask(tv);
    task.execute("moscow");
   }
}

这是获取选定城市的天气预报的主要Java类

public class WeatherTask extends AsyncTask<String, Void, String> {

private static final String API_KEY = "06c7d6512a914b3029937dd444283ff0";
private final TextView textView;


public WeatherTask(TextView tv){
    this.textView = tv;
}

@Override
protected String doInBackground(String... cities) {
    String weather = "";

    try {
        String urlString = String.format(
                "http://api.openweathermap.org/data/2.5/weather?q=%s,uz&units=%s&appid=%s",
                cities[0], "metric", API_KEY
        );

        URL url = new URL(urlString);
        HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();

        urlConnection.connect();

        InputStream stream = new BufferedInputStream(urlConnection.getInputStream());
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(stream));

        StringBuilder builder = new StringBuilder();
        String inputString;

        while ((inputString = bufferedReader.readLine()) != null) {
            builder.append(inputString);
        }

        String response = builder.toString();

        JSONObject topLevel = new JSONObject(response);

        JSONObject main = topLevel.getJSONObject("main");
        weather = String.valueOf(main.getDouble("temp"));
        urlConnection.disconnect();

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

    return weather;
}

@Override
protected void onPostExecute(String weather)
{
    this.textView.setText(weather);
   }
}

有人可以解释为什么在主活动中不显示textview吗？

谢谢

Answer 1

我尝试了您的URL，它返回的JSON响应具有不同的结构-表示未知城市。也许您想从查询中删除,uz：

"http://api.openweathermap.org/data/2.5/weather?q=%s&units=%s&appid=%s"

您还应该检查日志，e.printStacktrace会提供明确的错误消息。我还检查了uz是乌兹别克斯坦的国家/地区代码，但我确定莫斯科在俄罗斯，所以也许这是失败的原因，并解释了为什么您的TextView没有收到任何东西。

Answer 2

   A.A         A.B        A.C         B.A B.B        B.C        C.A        C.B C.C
1    1  0.38056317  0.4701251   2.6276847   1  1.2353406  2.1270933  0.8094934   1
2    1 -1.07851585 -1.0793270  -0.9272001   1  1.0007521 -0.9265032  0.9992484   1
3    1 -2.44512434 -4.7467554  -0.4089772   1  1.9413145 -0.2106702  0.5151149   1
4    1 -1.41765991 -2.3908820  -0.7053878   1  1.6864990 -0.4182557  0.5929443   1
5    1 -0.10640354  0.2382367  -9.3981837   1 -2.2389920  4.1975066 -0.4466296   1
6    1  2.32474492  0.3879095   0.4301547   1  0.1668611  2.5779212  5.9930092   1
7    1  0.95122898  1.6102188   1.0512716   1  1.6927773  0.6210336  0.5907452   1
8    1 -0.15996970 -0.1422422  -6.2511840   1  0.8891823 -7.0302611  1.1246287   1
9    1 -0.04431519  0.2121086 -22.5656275   1 -4.7863640  4.7145657 -0.2089269   1
10   1  0.26662240 -0.3524232   3.7506226   1 -1.3218065 -2.8374974 -0.7565404   1

应为：

http://api.openweathermap.org/data/2.5/weather?q=%s,uz&units=%s&appid=%s"

如果您使用第一个请求，应该有以下响应：

http://api.openweathermap.org/data/2.5/weather?q=%s&units=%s&appid=%s"

因为它将{ "cod": "404", "message": "city not found" }和'cities[0]'连接为第一个参数。

Textview没有显示

2 个答案: