Java 数据未显示在spinner中使用截击-真实设备问题

在中测试时，代码运行良好，但在spinner中测试相同代码时，代码未显示。甚至没有错误消息

Config.java

public class Config {

public static String mLocation ="http://towncitycards.com/webservice_action.php?action=";
//http://towncitycards.com/webservice_action.php?action=filter_location
public static final String DATA_URL = mLocation+"filter_location";

//Tags used in the JSON String
public static final String TAG_USERNAME = "name";
public static final String TAG_NAME = "slug";
public static final String TAG_COURSE = "name";
public static final String TAG_SESSION = "slug";

//JSON array name
public static final String JSON_ARRAY = "location";
}

public class DemoSpinner extends AppCompatActivity implements Spinner.OnItemSelectedListener{

//Declaring an Spinner
private Spinner spinner;

//An ArrayList for Spinner Items
private ArrayList<String> students;

//JSON Array
private JSONArray result;

//TextViews to display details
private TextView textViewName;
private TextView textViewCourse;
private TextView textViewSession;

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

    //Initializing the ArrayList
    students = new ArrayList<String>();

    //Initializing Spinner
    spinner = (Spinner) findViewById(R.id.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
    spinner.setOnItemSelectedListener(this);

    //Initializing TextViews
    textViewName = (TextView) findViewById(R.id.textViewName);
    textViewCourse = (TextView) findViewById(R.id.textViewCourse);
    textViewSession = (TextView) findViewById(R.id.textViewSession);

    //This method will fetch the data from the URL
    getData();
}

private void getData(){
    //Creating a string request
    StringRequest stringRequest = new StringRequest(Config.DATA_URL,
            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
                        result = j.getJSONArray(Config.JSON_ARRAY);

                        //Calling method getStudents to get the students from the JSON Array
                        getStudents(result);
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {

                }
            });

    //Creating a request queue
    RequestQueue requestQueue = Volley.newRequestQueue(this);

    //Adding request to the queue
    requestQueue.add(stringRequest);
}

private void getStudents(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
            students.add(json.getString(Config.TAG_USERNAME));
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

    //Setting adapter to show the items in the spinner
    spinner.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item, students));
}

//Method to get student name of a particular position
private String getName(int position){
    String name="";
    try {
        //Getting object of given index
        JSONObject json = result.getJSONObject(position);

        //Fetching name from that object
        name = json.getString(Config.TAG_NAME);
    } catch (JSONException e) {
        e.printStackTrace();
    }
    //Returning the name
    return name;
}

//Doing the same with this method as we did with getName()
private String getCourse(int position){
    String course="";
    try {
        JSONObject json = result.getJSONObject(position);
        course = json.getString(Config.TAG_COURSE);
    } catch (JSONException e) {
        e.printStackTrace();
    }
    return course;
}

//Doing the same with this method as we did with getName()
private String getSession(int position){
    String session="";
    try {
        JSONObject json = result.getJSONObject(position);
        session = json.getString(Config.TAG_SESSION);
    } catch (JSONException e) {
        e.printStackTrace();
    }
    return session;
}


//this method will execute when we pic an item from the spinner
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
    //Setting the values to textviews for a selected item
    textViewName.setText(getName(position));
    textViewCourse.setText(getCourse(position));
    textViewSession.setText(getSession(position));
}

//When no item is selected this method would execute
@Override
public void onNothingSelected(AdapterView<?> parent) {
    textViewName.setText("");
    textViewCourse.setText("");
    textViewSession.setText("");
}
}

DemoSpinner.java

public class Config {

public static String mLocation ="http://towncitycards.com/webservice_action.php?action=";
//http://towncitycards.com/webservice_action.php?action=filter_location
public static final String DATA_URL = mLocation+"filter_location";

//Tags used in the JSON String
public static final String TAG_USERNAME = "name";
public static final String TAG_NAME = "slug";
public static final String TAG_COURSE = "name";
public static final String TAG_SESSION = "slug";

//JSON array name
public static final String JSON_ARRAY = "location";
}

public class DemoSpinner extends AppCompatActivity implements Spinner.OnItemSelectedListener{

//Declaring an Spinner
private Spinner spinner;

//An ArrayList for Spinner Items
private ArrayList<String> students;

//JSON Array
private JSONArray result;

//TextViews to display details
private TextView textViewName;
private TextView textViewCourse;
private TextView textViewSession;

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

    //Initializing the ArrayList
    students = new ArrayList<String>();

    //Initializing Spinner
    spinner = (Spinner) findViewById(R.id.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
    spinner.setOnItemSelectedListener(this);

    //Initializing TextViews
    textViewName = (TextView) findViewById(R.id.textViewName);
    textViewCourse = (TextView) findViewById(R.id.textViewCourse);
    textViewSession = (TextView) findViewById(R.id.textViewSession);

    //This method will fetch the data from the URL
    getData();
}

private void getData(){
    //Creating a string request
    StringRequest stringRequest = new StringRequest(Config.DATA_URL,
            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
                        result = j.getJSONArray(Config.JSON_ARRAY);

                        //Calling method getStudents to get the students from the JSON Array
                        getStudents(result);
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {

                }
            });

    //Creating a request queue
    RequestQueue requestQueue = Volley.newRequestQueue(this);

    //Adding request to the queue
    requestQueue.add(stringRequest);
}

private void getStudents(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
            students.add(json.getString(Config.TAG_USERNAME));
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

    //Setting adapter to show the items in the spinner
    spinner.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item, students));
}

//Method to get student name of a particular position
private String getName(int position){
    String name="";
    try {
        //Getting object of given index
        JSONObject json = result.getJSONObject(position);

        //Fetching name from that object
        name = json.getString(Config.TAG_NAME);
    } catch (JSONException e) {
        e.printStackTrace();
    }
    //Returning the name
    return name;
}

//Doing the same with this method as we did with getName()
private String getCourse(int position){
    String course="";
    try {
        JSONObject json = result.getJSONObject(position);
        course = json.getString(Config.TAG_COURSE);
    } catch (JSONException e) {
        e.printStackTrace();
    }
    return course;
}

//Doing the same with this method as we did with getName()
private String getSession(int position){
    String session="";
    try {
        JSONObject json = result.getJSONObject(position);
        session = json.getString(Config.TAG_SESSION);
    } catch (JSONException e) {
        e.printStackTrace();
    }
    return session;
}


//this method will execute when we pic an item from the spinner
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
    //Setting the values to textviews for a selected item
    textViewName.setText(getName(position));
    textViewCourse.setText(getCourse(position));
    textViewSession.setText(getSession(position));
}

//When no item is selected this method would execute
@Override
public void onNothingSelected(AdapterView<?> parent) {
    textViewName.setText("");
    textViewCourse.setText("");
    textViewSession.setText("");
}
}

公共类DemoSpinner扩展AppCompative实现Spinner.OnItemSelectedListener{
//宣布成为纺纱工
私人纺纱机；
//微调器项的ArrayList
私立ArrayList学生；
//JSON数组
私人JSONArray结果；
//文本视图以显示详细信息
私有文本视图文本视图名称；
私人TextView TextView课程；
私有文本视图文本视图会话；
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.demo）；
//初始化ArrayList
学生=新数组列表（）；
//初始化微调器
微调器=（微调器）findViewById（R.id.spinner）；
//向微调器添加选定项侦听器
//由于我们已经将类Spinner.OnItemSelectedListener实现到这个类本身，我们将把它传递给setOnItemSelectedListener
spinner.setOnItemSelectedListener（此）；
//初始化文本视图
textViewName=（TextView）findViewById（R.id.textViewName）；
textViewCourse=（TextView）findViewById（R.id.textViewCourse）；
textViewSession=（TextView）findViewById（R.id.textViewSession）；
//此方法将从URL获取数据
getData（）；
}
私有void getData（）{
//创建字符串请求
StringRequest StringRequest=新的StringRequest（Config.DATA\u URL，
新的Response.Listener（）{
@凌驾
公共void onResponse（字符串响应）{
JSONObject j=null；
试一试{
//将获取的Json字符串解析为Json对象
j=新的JSONObject（响应）；
//将JSON字符串数组存储到我们的JSON数组中
result=j.getJSONArray（Config.JSON_数组）；
//调用getStudents方法从JSON数组中获取学生
获取学生（结果）；
}捕获（JSONException e）{
e、 printStackTrace（）；
}
}
},
新的Response.ErrorListener（）{
@凌驾
公共无效onErrorResponse（截击错误）{
}
});
//创建请求队列
RequestQueue RequestQueue=Volley.newRequestQueue（this）；
//将请求添加到队列
添加（stringRequest）；
}
私人学生（JSONArray j）{
//遍历json数组中的所有项
对于（int i=0；i父级）{
textViewName.setText（“”）；
textViewCourse.setText（“”）；
textViewSession.setText（“”）；
}
}

StringRequest-StringRequest=new-StringRequest（Request.Method.GET，Config.DATA\u URL，new-Response.Listener（）

在getData（）中使用它，因为未指定Request.Method.GET

：：或： 您可以这样使用：

new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {

        }
    }) {
        @Override
        protected Map<String, String> getParams() throws AuthFailureError {
            Map<String, String> params = new HashMap<String, String>();
            params.put("action", "filter_location");
            return params;
        }
    };

newresponse.ErrorListener（）{
@凌驾
公共无效onErrorResponse（截击错误）{
}
}) {
@凌驾
受保护的映射getParams（）引发AuthFailureError{
Map params=新的HashMap（）；
参数put（“动作”、“过滤器位置”）；
返回参数；
}
};

---

然后从url中删除参数“action=filter\u location”。

StringRequest StringRequest=new StringRequest（Request.Method.GET，Config.DATA\u url，new Response.Listener（）

在getData（）中使用它，因为未指定Request.Method.GET

：：或： 您可以这样使用：

new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {

        }
    }) {
        @Override
        protected Map<String, String> getParams() throws AuthFailureError {
            Map<String, String> params = new HashMap<String, String>();
            params.put("action", "filter_location");
            return params;
        }
    };

newresponse.ErrorListener（）{
@凌驾
公共无效onErrorResponse（截击错误）{
}
}) {
@凌驾
受保护的映射getParams（）引发AuthFailureError{
Map params=新的HashMap（）；
参数put（“动作”、“过滤器位置”）；
返回参数；
}
};

---

然后从url中删除参数“action=filter\u location”。

请使用此编辑的代码，这将适用于您：

public class DemoSpinner extends AppCompatActivity implements Spinner.OnItemSelectedListener{

//Declaring an Spinner
private Spinner spinner;

//An ArrayList for Spinner Items
private ArrayList<String> students;

//JSON Array
private JSONArray result;

//TextViews to display details
private TextView textViewName;
private TextView textViewCourse;
private TextView textViewSession;

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

    //Initializing the ArrayList
    students = new ArrayList<String>();

    //Initializing Spinner
    spinner = (Spinner) findViewById(R.id.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
    spinner.setOnItemSelectedListener(this);

    //Initializing TextViews
    textViewName = (TextView) findViewById(R.id.textViewName);
    textViewCourse = (TextView) findViewById(R.id.textViewCourse);
    textViewSession = (TextView) findViewById(R.id.textViewSession);

    //This method will fetch the data from the URL
    getData();
}

   private void getData(){


        //Creating a request queue

        JsonObjectRequest StringRequest = new JsonObjectRequest(Request.Method.GET, Config.DATA_URL, null,
                new Response.Listener<JSONObject>() {
                    @Override
                    public void onResponse(JSONObject response) {
                        if (response != null) {
                            JSONObject j = null;
                            try {
                                //Parsing the fetched Json String to JSON Object
                                j = response;

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

                                //Calling method getStudents to get the students from the JSON Array
                                getStudents(result);
                            } catch (JSONException e) {
                                e.printStackTrace();
                            }
                        }
                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        System.out.println("Volly error is this >>" + error);



                    }

                });

        RequestQueue requestQueue = Volley.newRequestQueue(this);
        requestQueue.add(StringRequest);
    }


    private void getStudents(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
                students.add(json.getString(Config.TAG_USERNAME));
            } catch (JSONException e) {
                e.printStackTrace();
            }
        }

        Log.e("student >>",students.toString());
        //Setting adapter to show the items in the spinner
        spinner.setAdapter(new ArrayAdapter<String>(this,  android.R.layout.simple_spinner_item, students));
    }


//Method to get student name of a particular position
private String getName(int position){
    String name="";
    try {
        //Getting object of given index
        JSONObject json = result.getJSONObject(position);

        //Fetching name from that object
        name = json.getString(Config.TAG_NAME);
    } catch (JSONException e) {
        e.printStackTrace();
    }
    //Returning the name
    return name;
}

//Doing the same with this method as we did with getName()
private String getCourse(int position){
    String course="";
    try {
        JSONObject json = result.getJSONObject(position);
        course = json.getString(Config.TAG_COURSE);
    } catch (JSONException e) {
        e.printStackTrace();
    }
    return course;
}

//Doing the same with this method as we did with getName()
private String getSession(int position){
    String session="";
    try {
        JSONObject json = result.getJSONObject(position);
        session = json.getString(Config.TAG_SESSION);
    } catch (JSONException e) {
        e.printStackTrace();
    }
    return session;
}


//this method will execute when we pic an item from the spinner
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
    //Setting the values to textviews for a selected item
    textViewName.setText(getName(position));
    textViewCourse.setText(getCourse(position));
    textViewSession.setText(getSession(position));
}

//When no item is selected this method would execute
@Override
public void onNothingSelected(AdapterView<?> parent) {
    textViewName.setText("");
    textViewCourse.setText("");
    textViewSession.setText("");
}
}

公共类DemoSpinner扩展AppCompative实现Spinner.OnItemSelectedListener{
//宣布成为纺纱工
私人纺纱机；
//微调器项的ArrayList
私立ArrayList学生；
//JSON数组
私人JSONArray结果；
//文本视图以显示详细信息
私有文本视图文本视图名称；
私人TextView TextView课程；
私有文本视图文本视图会话；
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.demo）；
//初始化ArrayList
学生=新数组列表（）；
//初始化微调器
微调器=（微调器）findViewById（R.id.spinner）；
//向微调器添加选定项侦听器
//由于我们已经将类Spinner.OnItemSelectedListener实现到这个类本身，我们将把它传递给setOnItemSelectedListener
spinner.setOnItemSelectedListener（此）；
//初始化文本视图
textViewName=（TextView）findViewById（R.id.textViewName）；
textViewCourse=（TextView）findViewById（R.id.textViewCourse）；
textViewSession=（TextView）findViewById（R.id.textViewSession）；
//此方法将从URL获取数据
getData（）；
}
私有void getData（）{
//创建请求队列
JsonObjectRequest StringRequest=新的JsonObjectRequest（Request.Method.GET，Config.DATA\u URL，null，
新的Response.Listener（）{
@凌驾
公共void onResponse（JSONObject响应）{
if（响应！=null）{
JSONObject j=null；
试一试{
//将获取的Json字符串解析为Json对象