怎样用android制作一个天气预报APP及代码实现

要制作一个天气预报APP，你需要掌握以下技能：

1. 掌握 Android Studio 的基本使用方法
2. 了解 Android 的基本布局和UI设计
3. 掌握网络请求与解析JSON数据
4. 掌握 Android 中的ListView、RecyclerView等控件
5. 掌握 Android 中的SharedPreferences存储

以下是一个简单的天气预报APP的代码实现，供你参考：

1. 布局文件（activity_main.xml）

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <TextView
        android:id="@+id/city_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="城市名称"
        android:textSize="24sp" />

    <TextView
        android:id="@+id/weather_info"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="天气信息"
        android:textSize="18sp" />

    <ListView
        android:id="@+id/list_view"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

2. Java 代码（MainActivity.java）

public class MainActivity extends AppCompatActivity {
    private TextView cityName;
    private TextView weatherInfo;
    private ListView listView;

    private List<String> forecastList = new ArrayList<>();
    private ArrayAdapter<String> adapter;

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

        cityName = findViewById(R.id.city_name);
        weatherInfo = findViewById(R.id.weather_info);
        listView = findViewById(R.id.list_view);

        adapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, forecastList);
        listView.setAdapter(adapter);

        String city = "北京"; // 待查询的城市名称
        queryWeather(city);
    }

    private void queryWeather(String city) {
        String url = "http://wthrcdn.etouch.cn/weather_mini?city=" + city;
        OkHttpClient client = new OkHttpClient();
        Request request = new Request.Builder()
                .url(url)
                .build();

        client.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                e.printStackTrace();
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                String responseData = response.body().string();
                try {
                    JSONObject jsonObject = new JSONObject(responseData);
                    JSONObject data = jsonObject.getJSONObject("data");

                    final String city = data.getString("city");
                    final String weather = data.getString("wendu") + "℃ " + data.getString("ganmao");

                    JSONArray forecast = data.getJSONArray("forecast");

                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            cityName.setText(city);
                            weatherInfo.setText(weather);
                        }
                    });

                    for (int i = 0; i < forecast.length(); i++) {
                        JSONObject item = forecast.getJSONObject(i);
                        String date = item.getString("date");
                        String high = item.getString("high");
                        String low = item.getString("low");
                        String type = item.getString("type");

                        final String forecastStr = date + "  " + type + "  " + low + "~" + high;

                        runOnUiThread(new Runnable() {
                            @Override
                            public void run() {
                                forecastList.add(forecastStr);
                                adapter.notifyDataSetChanged();
                            }
                        });
                    }
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }
        });
    }
}

以上代码只是一个简单的示例，实际制作中还需要考虑到错误处理、用户交互等方面。