java - 国家、州和城市微调器无法正常工作

Question

我一直在开发一个注册表单应用程序，其中使用了几个微调器小部件。微调器用于选择国家、州和城市。因此，这些微调器需要以某种方式相互连接(下面的代码将展示我如何尝试实现这一点)。

表单代码:

fragment 注册.xml

<?xml version="1.0" encoding="utf-8"?>

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:fillViewport="true">

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_marginLeft="40dp"
android:layout_marginRight="40dp"
android:gravity="center"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:nestedScrollingEnabled="true">


<TextView
    android:text="Student Registration Form"
    android:textSize="22sp"
    android:textAlignment="center"
    android:layout_marginBottom="20dp"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />

    <Spinner
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/country_spinner"
        android:foregroundTint="#222"
        android:background="#001c47"
        android:layout_marginBottom="20dp" />

    <Spinner
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/state_spinner"
        android:foregroundTint="#222"
        android:background="#001c47"
        android:layout_marginBottom="20dp" />

    <Spinner
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/city_spinner"
        android:foregroundTint="#222"
        android:background="#001c47"
        android:layout_marginBottom="20dp" />

</LinearLayout>
</ScrollView>

上面的代码有更多的小部件，您可能会在 java 文件中找到它们；我没有将它们包含在上面的代码中，因为它会变得太长。

RegisterFragement.java

import android.app.Fragment;
import android.app.FragmentTransaction;
import android.content.SharedPreferences;
import android.nfc.Tag;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;


import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.TextView;

import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;

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

import java.util.ArrayList;
import android.support.design.widget.Snackbar;
import android.support.v7.widget.AppCompatButton;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;


public class RegisterFragment extends Fragment  implements View.OnClickListener, Spinner.OnItemSelectedListener{

private AppCompatButton btn_register;
private EditText et_email,et_password,et_name;
private TextView tv_login;
private ProgressBar progress;
//Declaring the Spinners
private Spinner country_spinner;
private Spinner state_spinner;
private Spinner city_spinner;


//An ArrayList for Spinner Items
private ArrayList<String> results;
// countGetData: It will keep a count of how many times get data has been run and for 0 times
// it would set the spinners to default state
private int countGetData;
ArrayList student1 = new ArrayList();


//JSON Array
private JSONArray resultArray;


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.fragment_register,container,false);
    initViews(view);
    return view;

}

private void initViews(View view){

    btn_register = (AppCompatButton)view.findViewById(R.id.btn_register);
    tv_login = (TextView)view.findViewById(R.id.tv_login);
    et_name = (EditText)view.findViewById(R.id.et_name);
    et_email = (EditText)view.findViewById(R.id.et_email);
    et_password = (EditText)view.findViewById(R.id.et_password);

    progress = (ProgressBar)view.findViewById(R.id.progress);

    btn_register.setOnClickListener(this);
    tv_login.setOnClickListener(this);
    //Initializing the ArrayList
    results = new ArrayList<String>();
    // Initializing countGetData
    countGetData = 0;

    //Initializing Spinner
    country_spinner = (Spinner) view.findViewById(R.id.country_spinner);
    state_spinner = (Spinner) view.findViewById(R.id.state_spinner);
    city_spinner = (Spinner) view.findViewById(R.id.city_spinner);


    //Adding an Item Selected Listener to our Spinner
    //As we have implemented the class Spinner.OnItemSelectedListener to this class iteself we are passing this to setOnItemSelectedListener
    country_spinner.setOnItemSelectedListener(this);
    state_spinner.setOnItemSelectedListener(this);
    city_spinner.setOnItemSelectedListener(this);
    university_spinner.setOnItemSelectedListener(this);
    college_spinner.setOnItemSelectedListener(this);
    ca_spinner.setOnItemSelectedListener(this);


    getData("getCountries", "", 0);
}


@Override
public void onClick(View v) {

    switch (v.getId()){
        case R.id.tv_login:
            goToLogin();
            break;

        case R.id.btn_register:

            String name = et_name.getText().toString();
            String email = et_email.getText().toString();
            String password = et_password.getText().toString();

            if(!name.isEmpty() && !email.isEmpty() && !password.isEmpty()) {

                progress.setVisibility(View.VISIBLE);
                registerProcess(name,email,password);

            } else {

                Snackbar.make(getView(), "Fields are empty !", Snackbar.LENGTH_LONG).show();
            }
            break;

    }

}

private void getData(String urlPart1,String urlPart2, long itemId) {
    //Creating a string request
    StringRequest stringRequest = new StringRequest(Config.DATA_URL+urlPart1+"&"+urlPart2+"="+itemId,
            new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    JSONObject j = null;
                    try {
                        //Parsing the fetched Json String to JSON Object
                        j = new JSONObject(response);

                        //Storing the Array of JSON String to our JSON Array
                        resultArray = j.getJSONArray(Config.JSON_ARRAY);

                        //Calling method getStudents to get the students from the JSON Array
                        getResults(resultArray);

                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {

                }
            });

//Creating a request queue
        RequestQueue requestQueue = Volley.newRequestQueue(getActivity().getApplicationContext());
    //Adding request to the queue
    requestQueue.add(stringRequest);

}

private void getResults(JSONArray j) {
    //Traversing through all the items in the json array
    for (int i = 0; i < j.length(); i++) {
        try {
            //Getting json object
            JSONObject json = j.getJSONObject(i);

            //Adding the name of the student to array list
            results.add(json.getString(Config.TAG_NAME));
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

    if(countGetData == 0) {
        student1.add("Select This");
        //Setting adapter to show the items in the spinner
        country_spinner.setAdapter(new ArrayAdapter<String>(getActivity().getApplicationContext(), android.R.layout.simple_spinner_dropdown_item, results));
        state_spinner.setAdapter(new ArrayAdapter<String>(getActivity().getApplicationContext(), android.R.layout.simple_spinner_dropdown_item, student1));
        city_spinner.setAdapter(new ArrayAdapter<String>(getActivity().getApplicationContext(), android.R.layout.simple_spinner_dropdown_item, student1));
        countGetData += 1;
    }
}



//this method will execute when we pic an item from the spinner
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

    if(country_spinner.getSelectedItem().toString().equals("Austria")){
        long itemId = country_spinner.getSelectedItemId();
        getData("getStates","countryId",itemId);
        state_spinner.setAdapter(new ArrayAdapter<String>(getActivity().getApplicationContext(), android.R.layout.simple_spinner_dropdown_item, results));
    }
    else{
        long itemId = country_spinner.getSelectedItemId();
        getData("getStates","countryId",itemId);
        state_spinner.setAdapter(new ArrayAdapter<String>(getActivity().getApplicationContext(), android.R.layout.simple_spinner_dropdown_item, results));
    }


}
}

有一个 PHP API 可以根据 url 返回国家、州或城市的 json。例如: http://www.example.com/location_api/api.php?type=getCountries
http://www.example.com/location_api/api.php?type=getStates&countryId=12
http://www.example.com/location_api/api.php?type=getCities&stateId=1

在 onItemSelected 中，我试图根据前一个微调器动态设置微调器。 For ex., I'm setting the state spinner whenever a country spinner item is selected.我正在通过一个 if-else block 来检查它；如果条件检查是否选择了奥地利(列表中的国家之一；随机选择)然后设置state微调器else也设置< strong>状态微调器。这样，我最终根据国家/地区微调器元素设置了状态微调器。

为了向 API 指定选择哪个国家/地区，我使用了 itemId，它包含国家/地区微调器中所选项目的 ID。 long itemId = country_spinner.getSelectedItemId();

然后，当我获得 Id 时，我调用 getData 方法来设置 result ArraryList，并将其分配给微调器 state。

getData("getStates","countryId",itemId);
state_spinner.setAdapter(new ArrayAdapter<String>(getActivity().getApplicationContext(), android.R.layout.simple_spinner_dropdown_item, results));

上面的代码使应用程序在运行时崩溃并出现以下错误(我认为只有一部分可能有用，完整的 Logcat 文件在这里:Link):

--------- beginning of crash 04-13 21:05:09.782 9288-9600/com.gouravchawla.loginregistration E/AndroidRuntime: FATAL EXCEPTION: Thread-503 Process: com.gouravchawla.loginregistration, PID: 9288 java.lang.NegativeArraySizeException: -110 at com.android.volley.toolbox.DiskBasedCache.streamToBytes(DiskBasedCache.java:316) at com.android.volley.toolbox.DiskBasedCache.get(DiskBasedCache.java:117) at com.android.volley.CacheDispatcher.run(CacheDispatcher.java:101)

Throwing OutOfMemoryError "Failed to allocate a 1667853436 byte allocation with 777786 free bytes and 381MB until OOM"

Answer 1

例如，在您的代码中，您必须更改依赖于其他微调器的微调器的适配器。

城市 spinner适配器因州而异 spinner适配器
状态spinner适配器因国家/地区而异 spinner适配器，

我已经编写了一个示例代码来演示如何实现这一点，我已经编写了一个其他人在阅读答案时可以理解的通用代码，请随意提出建议并根据您的要求进行更改。

代码也可在 Github 上获得，以及另一个可以帮助您下​​载的示例 JSON来自它使用的网络的数据，OkHttp , GSON和 apache-common-io , code

public class SpinnerCountryActivity extends AppCompatActivity {

    private Spinner country_Spinner;
    private Spinner state_Spinner;
    private Spinner city_Spinner;

    private ArrayAdapter<Country> countryArrayAdapter;
    private ArrayAdapter<State> stateArrayAdapter;
    private ArrayAdapter<City> cityArrayAdapter;

    private ArrayList<Country> countries;
    private ArrayList<State> states;
    private ArrayList<City> cities;

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

        initializeUI();
    }

    private void initializeUI() {
        country_Spinner = (Spinner) findViewById(R.id.SpinnerCountryActivity_country_spinner);
        state_Spinner = (Spinner) findViewById(R.id.SpinnerCountryActivity_state_spinner);
        city_Spinner = (Spinner) findViewById(R.id.SpinnerCountryActivity_city_spinner);

        countries = new ArrayList<>();
        states = new ArrayList<>();
        cities = new ArrayList<>();

        createLists();

        countryArrayAdapter = new ArrayAdapter<Country>(getApplicationContext(), R.layout.simple_spinner_dropdown_item, countries);
        countryArrayAdapter.setDropDownViewResource(R.layout.simple_spinner_dropdown_item);
        country_Spinner.setAdapter(countryArrayAdapter);

        stateArrayAdapter = new ArrayAdapter<State>(getApplicationContext(), R.layout.simple_spinner_dropdown_item, states);
        stateArrayAdapter.setDropDownViewResource(R.layout.simple_spinner_dropdown_item);
        state_Spinner.setAdapter(stateArrayAdapter);

        cityArrayAdapter = new ArrayAdapter<City>(getApplicationContext(), R.layout.simple_spinner_dropdown_item, cities);
        cityArrayAdapter.setDropDownViewResource(R.layout.simple_spinner_dropdown_item);
        city_Spinner.setAdapter(cityArrayAdapter);

        country_Spinner.setOnItemSelectedListener(country_listener);
        state_Spinner.setOnItemSelectedListener(state_listener);
        city_Spinner.setOnItemSelectedListener(city_listener);

    }

    private AdapterView.OnItemSelectedListener country_listener = new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
            if (position > 0) {
                final Country country = (Country) country_Spinner.getItemAtPosition(position);
                Log.d("SpinnerCountry", "onItemSelected: country: "+country.getCountryID());
                ArrayList<State> tempStates = new ArrayList<>();

                tempStates.add(new State(0, new Country(0, "Choose a Country"), "Choose a State"));

                for (State singleState : states) {
                    if (singleState.getCountry().getCountryID() == country.getCountryID()) {
                        tempStates.add(singleState);
                    }
                }

                stateArrayAdapter = new ArrayAdapter<State>(getApplicationContext(), R.layout.simple_spinner_dropdown_item, tempStates);
                stateArrayAdapter.setDropDownViewResource(R.layout.simple_spinner_dropdown_item);
                state_Spinner.setAdapter(stateArrayAdapter);
            }

            cityArrayAdapter = new ArrayAdapter<City>(getApplicationContext(), R.layout.simple_spinner_dropdown_item, new ArrayList<City>());
            cityArrayAdapter.setDropDownViewResource(R.layout.simple_spinner_dropdown_item);
            city_Spinner.setAdapter(cityArrayAdapter);
        }

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

        }
    };

    private AdapterView.OnItemSelectedListener state_listener = new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
            if (position > 0) {
                final State state = (State) state_Spinner.getItemAtPosition(position);
                Log.d("SpinnerCountry", "onItemSelected: state: "+state.getStateID());
                ArrayList<City> tempCities = new ArrayList<>();

                Country country = new Country(0, "Choose a Country");
                State firstState = new State(0, country, "Choose a State");
                tempCities.add(new City(0, country, firstState, "Choose a City"));

                for (City singleCity : cities) {
                    if (singleCity.getState().getStateID() == state.getStateID()) {
                        tempCities.add(singleCity);
                    }
                }

                cityArrayAdapter = new ArrayAdapter<City>(getApplicationContext(), R.layout.simple_spinner_dropdown_item, tempCities);
                cityArrayAdapter.setDropDownViewResource(R.layout.simple_spinner_dropdown_item);
                city_Spinner.setAdapter(cityArrayAdapter);
            }
        }

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

        }
    };

    private AdapterView.OnItemSelectedListener city_listener = new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

        }

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

        }
    };

    private void createLists() {
        Country country0 = new Country(0, "Choose a Country");
        Country country1 = new Country(1, "Country1");
        Country country2 = new Country(2, "Country2");

        countries.add(new Country(0, "Choose a Country"));
        countries.add(new Country(1, "Country1"));
        countries.add(new Country(2, "Country2"));

        State state0 = new State(0, country0, "Choose a Country");
        State state1 = new State(1, country1, "state1");
        State state2 = new State(2, country1, "state2");
        State state3 = new State(3, country2, "state3");
        State state4 = new State(4, country2, "state4");

        states.add(state0);
        states.add(state1);
        states.add(state2);
        states.add(state3);
        states.add(state4);

        cities.add(new City(0, country0, state0, "Choose a City"));
        cities.add(new City(1, country1, state1, "City1"));
        cities.add(new City(2, country1, state1, "City2"));
        cities.add(new City(3, country1, state2, "City3"));
        cities.add(new City(4, country2, state2, "City4"));
        cities.add(new City(5, country2, state3, "City5"));
        cities.add(new City(6, country2, state3, "City6"));
        cities.add(new City(7, country2, state4, "City7"));
        cities.add(new City(8, country1, state4, "City8"));
    }

    private class Country implements Comparable<Country> {

        private int countryID;
        private String countryName;


        public Country(int countryID, String countryName) {
            this.countryID = countryID;
            this.countryName = countryName;
        }

        public int getCountryID() {
            return countryID;
        }

        public String getCountryName() {
            return countryName;
        }

        @Override
        public String toString() {
            return countryName;
        }


        @Override
        public int compareTo(Country another) {
            return this.getCountryID() - another.getCountryID();//ascending order
//            return another.getCountryID()-this.getCountryID();//descending  order
        }
    }

    private class State implements Comparable<State> {

        private int stateID;
        private Country country;
        private String stateName;

        public State(int stateID, Country country, String stateName) {
            this.stateID = stateID;
            this.country = country;
            this.stateName = stateName;
        }

        public int getStateID() {
            return stateID;
        }

        public Country getCountry() {
            return country;
        }

        public String getStateName() {
            return stateName;
        }

        @Override
        public String toString() {
            return stateName;
        }

        @Override
        public int compareTo(State another) {
            return this.getStateID() - another.getStateID();//ascending order
//            return another.getStateID()-this.getStateID();//descending order
        }
    }

    private class City implements Comparable<City> {

        private int cityID;
        private Country country;
        private State state;
        private String cityName;

        public City(int cityID, Country country, State state, String cityName) {
            this.cityID = cityID;
            this.country = country;
            this.state = state;
            this.cityName = cityName;
        }

        public int getCityID() {
            return cityID;
        }

        public Country getCountry() {
            return country;
        }

        public State getState() {
            return state;
        }

        public String getCityName() {
            return cityName;
        }

        @Override
        public String toString() {
            return cityName;
        }

        @Override
        public int compareTo(City another) {
            return this.cityID - another.getCityID();//ascending order
//            return another.getCityID() - this.cityID;//descending order
        }
    }
}

此代码使用三个数据模型类 Country , State和 City他们都实现了Comparable<T>这样它们的实例就可以在 List 中根据它们的 ID 进行排序。 , 你可能想使用 Comprator<T>这里按字母顺序排序。

我用过AdapterView.OnItemSelectedListener跟踪 Spinner 中的变化可以更改后续微调器适配器的小部件。

我添加了一些测试数据来演示代码是如何工作的

Country              Country1                   Country2  
                  ______|_____                 _____|_________
                  |           |               |               |
State          state1       state2         state3          state4
               __|___       ___|___        __|___          __|____
               |    |       |     |        |    |          |     |
City        city1 city2   city3 city4   city5 city6      city7 city8