Android Postcodes.io HTTP 请求

Question

我正在使用 AsyncHttpClient class，但我无法将结果保存为 OnSuccess 函数中的字符串。下面是我要解析的结果示例，我正在尝试检索 "lsoa" 值。

{
"status" : 200,
"result" : {
    "postcode" : "NW2 1SJ",
    "quality" : 1,
    "eastings" : 524332,
    "northings" : 186558,
    "country" : "England",
    "nhs_ha" : "London",
    "longitude" : -0.207661046004569,
    "latitude" : 51.5642021415348,
    "parliamentary_constituency" : "Finchley and Golders Green",
    "european_electoral_region" : "London",
    "primary_care_trust" : "Barnet",
    "region" : "London",
    "lsoa" : "Barnet 040A",
    "msoa" : "Barnet 040",
    "incode" : "1SJ",
    "outcode" : "NW2",
    "admin_district" : "Barnet",
    "parish" : "Barnet, unparished area",
    "admin_county" : null,
    "admin_ward" : "Childs Hill",
    "ccg" : "NHS Barnet",
    "nuts" : "Barnet",
    "codes" : {
        "admin_district" : "E09000003",
        "admin_county" : "E99999999",
        "admin_ward" : "E05000045",
        "parish" : "E43000193",
        "ccg" : "E38000005",
        "nuts" : "UKI71"
    }
}

我想做的就是将 API 中的 "lsoa" 存储到一个字符串中，但我什至无法将整个输出分配给一个字符串，因为我得到了 " 从内部 class 中访问变量 's'，需要声明为最终的”错误。

private void queryPostcodes(String searchString){

        String s;
        // Create a client to perform API request
        AsyncHttpClient client = new AsyncHttpClient();

        mDialog.show();

        // Output the link being checked
        Log.d("Gentrification: ", QUERY_URL + searchString);

        // Have the client get a JSONArray of data and define how to respond
        client.get(QUERY_URL + searchString, new JsonHttpResponseHandler(){

            @Override
            public void onSuccess(JSONObject jsonObject){
                mDialog.dismiss();
                Log.d("X: ", jsonObject.toString());
                s = jsonObject.toString(); //<-- DOESN'T WORK :(
            }

            @Override
            public void onFailure(int statusCode, Throwable throwable, JSONObject error){
                mDialog.dismiss();
                Toast.makeText(getApplicationContext(), "Error: " + statusCode + " " + throwable.getMessage() + " - Postcode not found", Toast.LENGTH_LONG).show();
                Log.e("X", statusCode + " " + throwable.getMessage());

            }
        });
    }

如有任何帮助，我们将不胜感激。

Answer 1

如果您尝试在 AndroidStudio 中按 Alt+Enter，您将看到一个快速修复选项：“将 's' 转换为一个元素数组”。单击并瞧瞧。

您的问题的原因是 new JsonHttpResponseHandler() 创建了匿名内部 class 的新实例。您要从内部访问的所有内容都应声明为父 class 的字段或包含方法中的最终变量。另一方面，您不能将 String 设为 final，因为 final 变量只会被赋值一次。您可以使用单个 String 参数创建包装器 class 或使 's' 成为父字段 class 或使用 String[] 作为包装器。

字符串包装器选项：

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final StringBuffer stringBuffer = new StringBuffer();
        Button updateButton = (Button) findViewById(R.id.update);
        updateButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                stringBuffer
                        .delete(0, stringBuffer.length())
                        .append(System.currentTimeMillis());
            }
        });
    }
}

父选项字段：

public class MainActivity extends AppCompatActivity {

    private String s;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button updateButton = (Button) findViewById(R.id.update);
        updateButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                s = String.valueOf(System.currentTimeMillis());
            }
        });
    }
}

字符串[]选项：

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final String[] s = new String[1];
        Button updateButton = (Button) findViewById(R.id.update);
        updateButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                s[0] = String.valueOf(System.currentTimeMillis());
            }
        });
    }
}

Android Postcodes.io HTTP 请求

Android Postcodes.io HTTP Request

java

android

android-async-http