android - 组织.json.JSONException : End of input at character 0 of

Question

我使用 JSONObject forecast = new JSONObject(response.body().string()) 来获取天气信息，但 android monitor 总是显示“org.json.JSONException: End of input at character 0 of”。

 import android.app.AlertDialog;
 import android.app.Dialog;
 import android.content.Context;
 import android.net.ConnectivityManager;
 import android.net.NetworkInfo;
 import android.os.Bundle;
 import android.os.Debug;
 import android.support.design.widget.FloatingActionButton;
 import android.support.design.widget.Snackbar;
 import android.support.v7.app.AppCompatActivity;
 import android.support.v7.widget.Toolbar;
 import android.util.Log;
 import android.view.View;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.widget.Toast;


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

 import java.io.IOException;

 import okhttp3.Call;
 import okhttp3.Callback;
 import okhttp3.OkHttpClient;
 import okhttp3.Request;
 import okhttp3.Response;

public class MainActivity extends AppCompatActivity {

private static final String TAG = MainActivity.class.getSimpleName();

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

    if(isconnected()){
        String url = "https://api.forecast.io/forecast/2d0f15adaeff2c8e1343201418843890/37.8267,-122.423";
        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) {

            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {

                if (response.isSuccessful()) {
                    Log.d(TAG, response.body().string());
                    String a=response.body().string();

                    try {
                        JSONObject forecast = new JSONObject(a);

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

                    }

                } else {
                    alertUserAboutError();

                }


            }
        });
    }

    else{
        Toast.makeText(MainActivity.this,"LOST CONNECTION",Toast.LENGTH_SHORT).show();
    }



    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    getSupportActionBar().hide();

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });
}

private boolean isconnected() {
    ConnectivityManager cm =
            (ConnectivityManager)MainActivity.this.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
    boolean isConnected = activeNetwork != null &&
            activeNetwork.isConnectedOrConnecting();
    return isConnected;

}

private void alertUserAboutError() {
    AlertDialogFragment alertDialogFragment = new AlertDialogFragment();
    alertDialogFragment.show(getSupportFragmentManager(), "error");

}

}

我使用 Log.d(TAG, response.body().string()) 来测试它是一个字符串，但是当在 JSONObject forecast = new JSONObject(response.body().string()) 中时，它将不起作用。

Answer 1

出于某种奇怪的原因，如果您使用 .string() >1 次，响应结果为空。在解析 Retrofit 响应时尽量只使用一次。

谁知道为什么会这样，请改进我的答案。