how to parse php (json) response in android.? : I am having json response like this..

    {"Fullname":" Prasad","vault_no":"12745"}.
How to convert this to string in android.This is my android class file.

**Register.class**

    package com.example.test;
    
    import android.app.Activity;
    import android.app.ProgressDialog;
    import android.content.Intent;
    import android.os.AsyncTask;
    import android.os.Bundle;
    import android.text.TextUtils;
    import android.view.View;
    import android.widget.ArrayAdapter;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.Spinner;
    import android.widget.TextView;
    import android.widget.Toast;
    
    import org.json.JSONObject;
    
    import java.util.HashMap;
    
    
    public class Register extends Activity implements View.OnClickListener{
    
    	
    	private static final int[] CategoryCode = new int[]{0,1,2,3}; // array to save Salutation code
    	private static final String[] Category = new String[]{"Cartegory","Male","Female","Company"}; // array to show Salutation
    
        private static final int[] SalutationCode = new int[]{0,1,2,3,4,5,6,7,8,9,0}; // array to save Salutation code
        private static final String[] Salutation = new String[]{"Salutation","Mr","Ms","SME(small scale)",
                "SU(start-up's)","SB(service based)","CA(charted accountant)","DR(doctor)",
        "LC(large scale)","Others", "None"};
    
    	private static final int[] CountryCode = new int[]{0,91}; // array to save Country code
    	private static final String[] Country = new String[]{"Country","India"}; // array to show Country name.
    	
    	private static final int[] CityCode = new int[]{0,1}; // array to save City code
    	private static final String[] City = new String[]{"City","Bangalore"}; // array to show City list
    
    	private static final int[] StateCode = new int[]{0,1}; // array to save State code
    	private static final String[] State = new String[]{"State","Karnataka"}; // array to show State list
    	
    	int selectedAreaCode;
    	private Spinner spin;
        private Spinner spin0;
    	private Spinner spin1;
    	private Spinner spin2;
    	private Spinner spin3;
        private EditText editTextFname;
        private EditText editTextLname;
        private EditText editTextDob;
        private EditText editTextPob;
        private EditText editTextMobile;
        private EditText editTextEmail;
        private EditText editTextPin;
        private Button register;
        private Button login;
    
        private static final String REGISTER_URL = "http://oursite/insert-db(1).php";
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            getActionBar().setDisplayShowTitleEnabled(false);
            setContentView(R.layout.activity_register_page);
    
            spin = (Spinner)findViewById(R.id.spinner1);
            spin0 = (Spinner)findViewById(R.id.spinner01);
            spin1 = (Spinner)findViewById(R.id.spinner2);
            spin2 = (Spinner)findViewById(R.id.spinner3);
            spin3 = (Spinner)findViewById(R.id.spinner4);
            editTextFname = (EditText) findViewById(R.id.editTextFname);
            editTextLname = (EditText) findViewById(R.id.editTextLname);
            editTextDob = (EditText)findViewById(R.id.editTextDob);
            editTextPob = (EditText)findViewById(R.id.editTextPob);
            editTextMobile = (EditText) findViewById(R.id.editTextMobile);
            editTextEmail = (EditText)findViewById(R.id.editTextEmail);
            editTextPin = (EditText) findViewById(R.id.editTextPin);
            
            register = (Button) findViewById(R.id.button);
            login = (Button) findViewById(R.id.button2);
            register.setOnClickListener(this);
    
            login.setOnClickListener(this);
            
            ArrayAdapter<String> adpt_area = new ArrayAdapter<String>(this,
                    android.R.layout.simple_spinner_item, Category);
            adpt_area.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
            spin.setAdapter(adpt_area);
    
            ArrayAdapter<String> cat = new ArrayAdapter<String>(this,
                    android.R.layout.simple_spinner_item, Salutation);
            cat.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
            spin0.setAdapter(cat);
    
            ArrayAdapter<String> adpt_country = new ArrayAdapter<String>(this,
                    android.R.layout.simple_spinner_item, Country);
            adpt_country.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
            spin1.setAdapter(adpt_country);
            
            ArrayAdapter<String> adpt_city = new ArrayAdapter<String>(this,
                    android.R.layout.simple_spinner_item, City);
            adpt_city.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
            spin2.setAdapter(adpt_city);
            
            ArrayAdapter<String> adpt_state = new ArrayAdapter<String>(this,
                    android.R.layout.simple_spinner_item, State);
            adpt_state.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
            spin3.setAdapter(adpt_state);
            
            
        }
    
        @Override
        public void onClick(View v) {
            if(v == register){
                registerUser();
            }
            if(v == login){
                startActivity(new Intent(this,LoginPage.class));
            }
        }
    
        private void registerUser() {
    
        	
        	String fname = editTextFname.getText().toString();
            
            if(TextUtils.isEmpty(fname)) {
            	editTextFname.setError("please enter first name");
                return;
             }
            
            String lname = editTextLname.getText().toString();
            
            if(TextUtils.isEmpty(lname)) {
            	editTextLname.setError("please enter last name");
                return;
             }
            
            String dob = editTextDob.getText().toString();
            
            if(TextUtils.isEmpty(dob)) {
            	editTextDob.setError("enter date of birth");
                return;
             }
            
            String pob = editTextPob.getText().toString();
            
            if(TextUtils.isEmpty(pob))	{
            	editTextPob.setError("enter the place of birth");
            	return;
            }
            
            String mobile = editTextMobile.getText().toString();
            
            if(TextUtils.isEmpty(mobile)) {
            	editTextMobile.setError("please enter mobile no");
                return;
             }
            
            String email = editTextEmail.getText().toString();
            if(TextUtils.isEmpty(email)) {
            	editTextEmail.setError("please enter the email id");
            	return;
            	
            }
            
            String pin = editTextPin.getText().toString();
    
            if(TextUtils.isEmpty(pin)) {
            	editTextPin.setError("please enter pin no");
                return;
             }
            
             int selectedPosition = spin.getSelectedItemPosition();
    	     // get area code based on value selected in spinner
    	     String category = String.valueOf(CategoryCode[selectedPosition]);
    
            int selectedPosition0 = spin0.getSelectedItemPosition();
            // get area code based on value selected in spinner
            String salutation = String.valueOf(SalutationCode[selectedPosition0]);
         
    	     int selectedPosition1 = spin1.getSelectedItemPosition();
    	     // get area code based on value selected in spinner
    	     String country = String.valueOf(CountryCode[selectedPosition1]);
         
    	     int selectedPosition2 = spin2.getSelectedItemPosition();
    	     // get area code based on value selected in spinner
    	     String state = String.valueOf(StateCode[selectedPosition2]);
    	     
    	     int selectedPosition3 = spin3.getSelectedItemPosition();
    	     // get area code based on value selected in spinner
    	     String city = String.valueOf(CityCode[selectedPosition3]);
    	    
    
            register(salutation,category,fname,lname,dob,pob,mobile,email,country,state,city,pin);
        }
    
        private void register(String salutation, String category, String fname, String lname,String dob,String pob,String mobile, String  email,String country, String state, String city, String pin) {
            class RegisterUser extends AsyncTask<String, Void, String>{
                ProgressDialog loading;
                //RegisterUserClass ruc = new RegisterUserClass();
                RequestHandler ruc = new RequestHandler();
    
                @Override
                protected void onPreExecute() {
                    super.onPreExecute();
                    loading = ProgressDialog.show(Register.this, "Please Wait",null, true, true);
                }
    
                @Override
                protected void onPostExecute(String s) {
                    super.onPostExecute(s);
                    loading.dismiss();
                    Toast.makeText(getApplicationContext(),"Successfully Registered..!!",Toast.LENGTH_LONG).show();
                    editTextFname.setText("");
                    editTextLname.setText("");
                    editTextDob.setText("");
                    editTextPob.setText("");
                    editTextMobile.setText("");
                    editTextEmail.setText("");
                    editTextPin.setText("");
    
                    Intent i = new Intent(Register.this,UserProfile.class);
                    i.putExtra("s", s);
                    startActivity(i);
                }
    
                @Override
                protected String doInBackground(String... params) {
    
                    HashMap<String, String> data = new HashMap<String,String>();
                    data.put("salutation",params[0]);
                    data.put("category",params[1]);
                    data.put("fname",params[2]);
                    data.put("lname",params[3]);
                    data.put("dob",params[4]);
                    data.put("pob",params[5]);
                    data.put("mobile",params[6]);
                    data.put("email", params[7]);
                    data.put("country",params[8]);
                    data.put("state",params[9]);
                    data.put("city",params[10]);
                    data.put("pin",params[11]);
    
    
                    String result = ruc.sendPostRequest(REGISTER_URL,data);
    
                    return  result;
                }
            }
    
            RegisterUser ru = new RegisterUser();
            ru.execute(salutation,category,fname,lname,dob,pob,mobile,email,country,state,city,pin);
        }
    }
The String "**s**" in **onPostExecute(String s)** will hold the json value..how to convert it to string and pass it to next page.


**RequestHandler.class**

    package com.example.test;
    
    import java.io.BufferedReader;
    import java.io.BufferedWriter;
    import java.io.InputStreamReader;
    import java.io.OutputStream;
    import java.io.OutputStreamWriter;
    import java.io.UnsupportedEncodingException;
    import java.net.HttpURLConnection;
    import java.net.URL;
    import java.net.URLEncoder;
    import java.util.HashMap;
    import java.util.Map;
    
    import javax.net.ssl.HttpsURLConnection;
    
    public class RequestHandler {
    
        public String sendPostRequest(String requestURL,
                                      HashMap<String, String> postDataParams) {
    
            URL url;
    
            StringBuilder sb = new StringBuilder();
            try {
                url = new URL(requestURL);
    
                HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                conn.setReadTimeout(15000);
                conn.setConnectTimeout(15000);
                conn.setRequestMethod("POST");
                conn.setDoInput(true);
                conn.setDoOutput(true);
    
    
                OutputStream os = conn.getOutputStream();
                BufferedWriter writer = new BufferedWriter(
                        new OutputStreamWriter(os, "UTF-8"));
                writer.write(getPostDataString(postDataParams));
    
                writer.flush();
                writer.close();
                os.close();
                int responseCode = conn.getResponseCode();
    
                if (responseCode == HttpsURLConnection.HTTP_OK) {
                    BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
                    sb = new StringBuilder();
                    String response;
                    while ((response = br.readLine()) != null){
                        sb.append(response);
                    }
                }
    
            } catch (Exception e) {
                e.printStackTrace();
            }
            return sb.toString();
        }
    
        private String getPostDataString(HashMap<String, String> params) throws UnsupportedEncodingException {
            StringBuilder result = new StringBuilder();
            boolean first = true;
            for (Map.Entry<String, String> entry : params.entrySet()) {
                if (first)
                    first = false;
                else
                    result.append("&");
    
                result.append(URLEncoder.encode(entry.getKey(), "UTF-8"));
                result.append("=");
                result.append(URLEncoder.encode(entry.getValue(), "UTF-8"));
            }
    
            return result.toString();
        }
    }