标签：java android android-studio android-spinner android-volley
我一直在研究注册表单应用程序,其中使用了很少的微调器小部件.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(下面的代码将显示我是如何尝试实现的).
表格代码：
fragment_register.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,你可以在java文件中找到它们;我没有将它们包含在上面的代码中,因为它会使它太长.
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 one rrorResponse(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,它根据url返回Country,State或City的json.例如：
http://www.example.com/location_api/api.php?type=getCountries
http://www.example.com/location_api/api.php?type=getStates\u0026amp;countryId=12
http://www.example.com/location_api/api.php?type=getCities\u0026amp;stateId=1
在onItemSelected中,我试图相对于前一个微调器动态设置微调器.例如,每当选择country spinner项时,我都会设置状态微调器.我正在通过if-else块检查这个;如果条件检查是否选择了奥地利(列表中的一个国家;随机选择),则设置状态微调器,否则也设置状态微调器.这样我最终根据country spinner元素设置状态微调器.
要向API指定正在选择的国家/地区,我正在使用itemId,其中包含国家/地区微调器中所选项目的ID.
long itemId = country_spinner.getSelectedItemId();
然后当我有Id我调用getData方法设置结果ArraryList并将其分配给微调器状态.
的getData( “的getStates”, “countryId” 的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(我认为其中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”
解决方法:
在您的代码中,您将不得不更改微调器的适配器,该适配器依赖于其他微调器.
City微调器适配器根据State微调器适配器更改
那也是
Statespinner适配器更改取决于Countryspinner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,我编写了一个通用代码,其他人可以在阅读答案时理解,随意建议并根据您的要求进行更改.
代码也可以在Github上获得,另一个例子可以帮助您从它使用的网络下载JSON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
}
}
}
该代码使用三个数据模型类Country,State和City,它们都实现了Comparable< T>因此,他们的实例可以根据列表中的ID进行排序,您可能希望使用Comprator< T>这里按字母顺序排序.
我使用了AdapterView.OnItemSelectedListener来跟踪Spinner小部件中可以更改后续微调器适配器的更改.
我添加了一些测试数据来演示代码的工作原理
Country Country1 Country2
______|_____ _____|_________
| | | |
State state1 state2 state3 state4
__|___ ___|___ __|___ __|____
| | | | | | | |
City city1 city2 city3 city4 city5 city6 city7 city8
标签：java,android,android-studio,android-spinner,android-volley 来源： https://codeday.me/bug/20190611/1219948.html
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