Problem in Android Studio, at the time of making the layout change with the raddio button the application closes on the cell phone

package com.example.marcelosegovia.servicioswebunid;

import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

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

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

/**
 * Created by Marcelo Segovia on 15/11/2017.
 */

public class AgregarContactoActivity extends AppCompatActivity implements View.OnClickListener{

    Intent ventana;
    String usuario;

    EditText nombre;
    EditText apodo;
    EditText movil;
    EditText casa;
    EditText email;
    Button guardar;

    String IP = "http://192.168.1.7/agenda";
    String INSERT = IP + "/insertar_contacto.php";

    ObtenerWebService hiloconexion;

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

        Bundle datos = getIntent().getExtras();
        usuario = datos.getString("nombre");

        nombre = (EditText)findViewById(R.id.nombre);
        apodo = (EditText)findViewById(R.id.apodo);
        movil = (EditText)findViewById(R.id.movil);
        casa = (EditText) findViewById(R.id.casa);
        email = (EditText) findViewById(R.id.email);
        guardar = (Button)findViewById(R.id.guardar);

        guardar.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {

        hiloconexion = new ObtenerWebService();
        hiloconexion.execute(INSERT,"5",nombre.getText().toString(),apodo.getText().toString(),
                movil.getText().toString(),casa.getText().toString(),email.getText().toString());



    }

    public class ObtenerWebService extends AsyncTask<String,Void,String> {

        @Override
        protected String doInBackground(String... params) {

            String cadena = params[0];
            URL url = null; // Url de donde queremos obtener información
            String devuelve ="";

            try {
                HttpURLConnection urlConn;

                DataOutputStream printout;
                DataInputStream input;
                url = new URL(cadena);
                urlConn = (HttpURLConnection) url.openConnection();
                urlConn.setDoInput(true);
                urlConn.setDoOutput(true);
                urlConn.setUseCaches(true);
                urlConn.setRequestProperty("Content-Type", "application/json");
                urlConn.setRequestProperty("Accept", "application/json");
                urlConn.connect();
                //Creo el Objeto JSON
                JSONObject jsonParam = new JSONObject();
                jsonParam.put("nombre", params[2]);
                jsonParam.put("apodo", params[3]);
                jsonParam.put("movil", params[4]);
                jsonParam.put("casa", params[5]);
                jsonParam.put("email", params[6]);
                // Envio los parámetros post.
                OutputStream os = urlConn.getOutputStream();
                BufferedWriter writer = new BufferedWriter(
                        new OutputStreamWriter(os, "UTF-8"));
                writer.write(jsonParam.toString());
                writer.flush();
                writer.close();

                int respuesta = urlConn.getResponseCode();

                StringBuilder result = new StringBuilder();

                if (respuesta == HttpURLConnection.HTTP_OK) {

                    String line;
                    BufferedReader br=new BufferedReader(new InputStreamReader(urlConn.getInputStream()));
                    while ((line=br.readLine()) != null) {
                        result.append(line);
                    }

                    //Creamos un objeto JSONObject para poder acceder a los atributos (campos) del objeto.
                    JSONObject respuestaJSON = new JSONObject(result.toString());   //Creo un JSONObject a partir del StringBuilder pasado a cadena
                    //Accedemos al vector de resultados

                    String resultJSON = respuestaJSON.getString("estado");   // estado es el nombre del campo en el JSON

                    if (resultJSON == "1") {
                        devuelve = "Contacto guardado correctamente";

                    } else if (resultJSON == "2") {
                        devuelve = "El contacto no pudo guardarse";
                    }

                }

            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } catch (JSONException e) {
                e.printStackTrace();
            }
            return devuelve;
        }

        @Override
        protected void onCancelled(String s) {
            super.onCancelled(s);
        }

        @Override
        protected void onPostExecute(String s) {
            verifica(s);
        }

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
        }

        @Override
        protected void onProgressUpdate(Void... values) {
            super.onProgressUpdate(values);
        }
    }

    public void verifica(String s){

        if (s.equals("Contacto guardado correctamente")  ){

            Toast.makeText(this, nombre.getText(), Toast.LENGTH_SHORT).show();
            Toast.makeText(this, "Ha sido registrado", Toast.LENGTH_SHORT).show();
            ventana = new Intent(AgregarContactoActivity.this, keyActivity.class);
            ventana.putExtra("nombre", usuario);
            startActivity(ventana);

        }else {
            Toast.makeText(this, "No se pudo completar el registro", Toast.LENGTH_SHORT).show();
            nombre.setText("");
            apodo.setText("");
            movil.setText("");
            casa.setText("");
            email.setText("");
        }
    }
}