如何获取根据 JAVA 中的用户选择而变化的 JsonObjects？

Posted 2023-04-19

【中文标题】如何获取根据 JAVA 中的用户选择而变化的 JsonObjects？

【英文标题】：How can I fetch JsonObjects that change according to user selection in JAVA?

【发布时间】：2021-07-13 06:11:12

【问题描述】：

我正在使用免费货币转换器 API 开发货币转换器应用程序，我设法将 JSON 提取到 Logcat 中，但我需要从中获取 JSON 对象的值 这是 JSON：

  "USD_INR": 74.61395

印度卢比和美元会根据用户的选择而变化，所以我怎样才能将数据输入我的应用程序，如下所示： 示例：

weatherData.mCity = jsonObject.getString("name");

这是我的代码：

package com.example.currencyconverter;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.Spinner;

import com.loopj.android.http.AsyncHttpClient;
import com.loopj.android.http.JsonHttpResponseHandler;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import cz.msebera.android.httpclient.Header;

import static com.loopj.android.http.AsyncHttpClient.log;

public class MainActivity extends AppCompatActivity 
//    https://free.currconv.com/api/v7/convert?q=USD_INR&compact=ultra&apiKey=38b9f7e70c1b1eb6089e


    private String URL = "https://free.currconv.com/api/v7/convert?q=";
    private final String URL_BALANCE = "&compact=ultra&apiKey=38b9f7e70c1b1eb6089e";
    private final String API_KEY = "38b9f7e70c1b1eb6089e";
    String result;
    String[] currency1;
    String[] currency2;
    String name;

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

        Spinner spinner1 = findViewById(R.id.spinner1);
        Spinner spinner2 = findViewById(R.id.spinner2);
        Button myButton = findViewById(R.id.button);

        currency1 = new String[1];
        currency2 = new String[1];



        ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this, R.array.currency_array, R.layout.custom_spinner);

        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

        spinner1.setAdapter(adapter);
        spinner1.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() 
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) 
                currency1[0] = parent.getItemAtPosition(position).toString();
                Log.d("myApp", "currency:" + currency1[0]);
                name = '\u0022' + currency1[0] + "_" + currency2[0] + '\u0022';


            

            @Override
            public void onNothingSelected(AdapterView<?> parent) 

            
        );

        spinner2.setAdapter(adapter);
        spinner2.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() 
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) 
                currency2[0] = parent.getItemAtPosition(position).toString();
                Log.d("myApp", "currency:" + currency2[0]);
                name = '\u0022' + currency1[0] + "_" + currency2[0] + '\u0022';

            

            @Override
            public void onNothingSelected(AdapterView<?> parent) 

            
        );

        myButton.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View v) 



                String finalURL = URL + currency1[0] + "_" + currency2[0] + URL_BALANCE;

                log.d("myApp", "url:" + finalURL);
                Log.d("myApp", "json:" + name);


                networking(finalURL);


            
        );


    


    private void networking(String url) 
        AsyncHttpClient client = new AsyncHttpClient();
        client.get(url, new JsonHttpResponseHandler() 

            @Override
            public void onSuccess(int statusCode, Header[] headers, JSONObject response) 
                Log.d("myApp", "JSON" + response.toString());
                try 

                    

                    result = response.getString(name);
                    Log.d("myApp", "result" + result);


                 catch (JSONException e) 
                    e.printStackTrace();

                

            

            @Override
            public void onFailure(int statusCode, Header[] headers, Throwable throwable, JSONObject errorResponse) 
                Log.d("myApp", "Request Failed:" + statusCode);
                Log.d("myApp", "Response Fail:" + errorResponse);
                Log.d("myApp", "Error:" + throwable.toString());

            
        );
    

这是我得到的输出：

2021-04-19 08:17:00.803 16457-16457/com.example.currencyconverter D/myApp: currency:USD
2021-04-19 08:17:03.877 16457-16457/com.example.currencyconverter D/myApp: currency:INR
2021-04-19 08:17:04.962 16457-16457/com.example.currencyconverter V/myApp: url:https://free.currconv.com/api/v7/convert?q=USD_INR&compact=ultra&apiKey=38b9f7e70c1b1eb6089e
2021-04-19 08:17:04.962 16457-16457/com.example.currencyconverter D/myApp: json:"USD_INR"
2021-04-19 08:17:06.287 16457-16457/com.example.currencyconverter D/myApp: JSON"USD_INR":74.61395

【参考方案1】：

使用 jsonObject.keys() 获取 JSON 对象的所有键。然后您可以循环返回值并请求与该键关联的值。

【参考方案2】：

我找到了解决办法：

     Iterator<String> keys = response.keys();
     while (keys.hasNext()) 
            String keyValue = keys.next();
            String valueString = response.getString(keyValue);