Develop Reference

Android App not responding after music service has started

I have an android app in which I have an activity and a service.
The service is supposed to play music and switch between four songs (depends on what button you press)
The problem is that a few minutes/seconds (it's not always at the same time) after you start the service by playing a song a notification pop ups which claims that the 'app has stopped responding' (with the option to wait and the option to exit). If you press the wait button the notification just goes away and the app and music continues the same. The notification will keep coming back though and unfortunately I am not sure why.
Should probably mention that this only happens to me when the service is on. I have tested this app many times. Never have a notification like that. Only when music is played.
My service:
package com.example.project25112021;
import android.app.Service;
import android.content.Intent;
import android.graphics.drawable.Drawable;
import android.media.MediaPlayer;
import android.os.IBinder;
import android.widget.Toast;
import androidx.annotation.Nullable;
public class MyService extends Service {
MediaPlayer mediaPlayer;
MediaPlayer mediaPlayer2;
MediaPlayer mediaPlayer3;
MediaPlayer mediaPlayer4;
#Nullable
#Override
public IBinder onBind(Intent intent) {
return null;
}
#Override
public void onCreate() {
super.onCreate();
mediaPlayer = MediaPlayer.create(this, R.raw.stronger);
mediaPlayer.setLooping(true); // Set looping
mediaPlayer.setVolume(100, 100);
mediaPlayer2 = MediaPlayer.create(this, R.raw.silksonic);
mediaPlayer2.setLooping(true); // Set looping
mediaPlayer2.setVolume(100, 100);
mediaPlayer3 = MediaPlayer.create(this, R.raw.davidguetta);
mediaPlayer3.setLooping(true); // Set looping
mediaPlayer3.setVolume(100, 100);
mediaPlayer4 = MediaPlayer.create(this, R.raw.beatit);
mediaPlayer4.setLooping(true); // Set looping
mediaPlayer4.setVolume(100, 100);
}
public int onStartCommand(Intent intent, int flags, int startId) {
int number = intent.getIntExtra("key", 0);
mediaPlayer.start();
mediaPlayer2.start();
mediaPlayer3.start();
mediaPlayer4.start();
mediaPlayer.seekTo(0);
mediaPlayer2.seekTo(0);
mediaPlayer3.seekTo(0);
mediaPlayer4.seekTo(0);
mediaPlayer.pause();
mediaPlayer2.pause();
mediaPlayer3.pause();
mediaPlayer4.pause();
if (number == 0){
mediaPlayer.start();
}
if (number == 1){
mediaPlayer2.start();
}
if (number == 2){
mediaPlayer3.start();
}
if (number == 3){
mediaPlayer4.start();
}
return startId;
}
//public void onStart(Intent intent, int startId) { }
#Override
public void onDestroy() {
mediaPlayer.stop();
mediaPlayer.release();
}
#Override
public void onLowMemory() {
}
}
The activity in which you choose what song to play:
package com.example.project25112021;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.graphics.drawable.Drawable;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.LinearLayout;
public class SettingsMain extends AppCompatActivity {
Button button;
Button song1;
Button song2;
Button song3;
Button song4;
ImageView album1;
ImageView album2;
ImageView album3;
ImageView album4;
Drawable drawable;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_settings_main);
drawable = CameraBackground.getInstance().getBitmap();
LinearLayout relative = (LinearLayout) findViewById(R.id.ButtonFinBack);
if(drawable!= null) {
relative.setBackgroundDrawable(drawable);
}
else
relative.setBackgroundResource(R.drawable.bacckga1);
button = findViewById(R.id.button2);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(SettingsMain.this, MainActivity.class);
startActivity(intent);
}
});
song1 = findViewById(R.id.song1);
song2 = findViewById(R.id.song2);
song3 = findViewById(R.id.song3);
song4 = findViewById(R.id.song4);
album1 = findViewById(R.id.album1);
album2 = findViewById(R.id.album2);
album3 = findViewById(R.id.album3);
album4 = findViewById(R.id.album4);
album1.setImageResource(R.drawable.kanye);
album2.setImageResource(R.drawable.silksonic);
album3.setImageResource(R.drawable.davidguetta);
album4.setImageResource(R.drawable.mjthriller);
song1.setText("Play");
song2.setText("Play");
song3.setText("Play");
song4.setText("Play");
song1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(SettingsMain.this, MyService.class);
intent.putExtra("key",0);
startService(intent);
}
});
song2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(SettingsMain.this, MyService.class);
intent.putExtra("key",1);
startService(intent);
}
});
song3.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(SettingsMain.this, MyService.class);
intent.putExtra("key",2);
startService(intent);
}
});
song4.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(SettingsMain.this, MyService.class);
intent.putExtra("key",3);
startService(intent);
}
});
}
}
Thanks

Code doesn't work

I'm trying to make an APK that saves passwords with the site using two different ArrayLists. This way, I can get the right indexnumber of the site and get the password based on this indexnumber. In the beginning of MainActivity, I add two random Strings to the ArrayLists, so that I don't have to work with empty ArrayLists, but this is utterly useless I think.
The problem is I can only view the last site-password I have put in. Previous combinations are "lost."
code:
MainActivity.java
package com.example.prive.passwordsafe;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
public ArrayList<String> passwordList = new ArrayList<>();
public ArrayList<String> siteList = new ArrayList<>();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
passwordList.add("ejifjejfijeifjeijfiejifjeijfiejfijefie");
siteList.add("iejfijeifjiejfiejidvjijijeijivjiejvijeivjejv");
Button addButton = (Button) findViewById(R.id.addButton);
Button showButton = (Button) findViewById(R.id.showButton);
addButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
firstIntent();
}
});
showButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
secondIntent();
}
});
}
#Override
public void onResume(){
super.onResume();
add();
}
private void firstIntent() {
Intent intent = new Intent(MainActivity.this, addActivity.class);
intent.putStringArrayListExtra("passwordList", passwordList);
intent.putStringArrayListExtra("siteList", siteList);
startActivity(intent);
}
private void secondIntent() {
Intent intent = new Intent(MainActivity.this, showActivity.class);
intent.putStringArrayListExtra("passwordList", passwordList);
intent.putStringArrayListExtra("siteList", siteList);
startActivity(intent);
}
public void add(){
Bundle pickupData = getIntent().getExtras();
if(pickupData == null){
return;
}
String receivedPassword = pickupData.getString("Password");
String receivedSite;
receivedSite = pickupData.getString("Site");
passwordList.add(receivedPassword);
siteList.add(receivedSite);
}
}
addActivity.java
package com.example.prive.passwordsafe;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class addActivity extends AppCompatActivity {
public EditText siteInsert, passwordInsert;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_toevoeg);
siteInsert = (EditText) findViewById(R.id.siteInsert);
passwordInsert = (EditText) findViewById(R.id.passwordInsert);
siteInsert.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Toast msg = Toast.makeText(getBaseContext(), "site", Toast.LENGTH_LONG);
msg.show();
}
});
passwordInsert.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Toast msg = Toast.makeText(getBaseContext(), "password", Toast.LENGTH_LONG);
msg.show();
}
});
Button button = (Button) findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
String password = passwordInsert.getText().toString();
String site = siteInsert.getText().toString();
Intent intent = new Intent(addActivity.this, MainActivity.class);
intent.putExtra("Password", password);
intent.putExtra("Site", site);
startActivity(intent);
}
});
}
}
showActivity.java
package com.example.prive.passwordsafe;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import java.util.ArrayList;
public class showActivity extends AppCompatActivity {
public EditText editText;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_toon);
Button showButton = (Button) findViewById(R.id.showButton);
Button backButton = (Button) findViewById(R.id.backButton);
editText = (EditText) findViewById(R.id.editText);
final TextView textView = (TextView) findViewById(R.id.textView);
Bundle pickupData = getIntent().getExtras();
final ArrayList<String> passwordList = pickupData.getStringArrayList("passwordList");
final ArrayList<String> siteList = pickupData.getStringArrayList("siteList");
editText.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Toast msg = Toast.makeText(getBaseContext(), "site", Toast.LENGTH_LONG);
msg.show();
}
});
if (passwordenList != null && siteList != null) {
showButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
int numberOfPasswords = passwordenList.size();
for (int i = 0; i <= numberOfPasswords; i++) {
String password;
String temporary = editText.getText().toString();
if (temporary.equals(siteList.get(i))) {
password = passwordList.get(i);
textView.setText(password);
}else{
password = "wrong input";
textView.setText(password);
}
}
}
});
}else{
return;
}
backButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
finish();
}
});
}
}

When you exit an Activity, all the data on it is lost. You have to persist your ArrayList in SQLite or use SharedPreferences instead.
SharedPreferences: https://developer.android.com/reference/android/content/SharedPreferences.html
SQLite: https://developer.android.com/training/basics/data-storage/databases.html

Android studio use same integer in 2 activities

i was making an android app and i need to use one integer value in 2 activities. I tried using this code but it didn't work.
//Integer Sender
Intent myIntent = new Intent(A.this, B.class);
myIntent.putExtra("MyIntNameGoesHere", intValue);
startActivity(myIntent);
//Integer receiver
Intent mIntent = getIntent();
int intValue = mIntent.getIntExtra("intVariableName", 0);
It says Cannot resolve symbol intValue and Cannot resolve symbol A and the same for B.
Here's the whole code.
MainActivity:
import android.content.Intent;
import android.content.SharedPreferences;
import android.preference.PreferenceManager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
int balance;
private SharedPreferences preferences;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Hide notification bar
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
//Click counter
final TextView text = (TextView) findViewById(R.id.balance_text);
assert text != null;
// to retreuve the values from the shared preference
preferences = PreferenceManager.getDefaultSharedPreferences(this);
balance = preferences.getInt("balance", 0);
text.setText(balance + " $");
final ImageButton button = (ImageButton) findViewById(R.id.click_button);
assert button != null;
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
balance++;
text.setText("" + balance + " $");
SharedPreferences.Editor editor = preferences.edit();
editor.putInt("balance", balance);
editor.apply();
}
});
final Button UpgradesButton = (Button) findViewById(R.id.upgrades_button);
assert UpgradesButton != null;
UpgradesButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(MainActivity.this, UpgradesActivity.class));
}
});
//Balance Integer Sender
}
}
UpgradesActivity:
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
public class UpgradesActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_upgrades);
//Hide notification bar
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
final Button e2u_button = (Button) findViewById(R.id.e2u_button);
assert e2u_button != null;
e2u_button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
}
});
final Button back_button = (Button) findViewById(R.id.back_button);
assert back_button != null;
back_button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(UpgradesActivity.this, MainActivity.class));
}
});
//TODO: Pass balance integer from MainActivity to here.
}
}
Error code:
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
public class UpgradesActivity extends AppCompatActivity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_upgrades);
//Receive balance from MainActivity
Intent mIntent = getIntent();
int intValue = mIntent.getIntExtra("key_int", 0);
//Hide notification bar
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
final Button e2u_button = (Button) findViewById(R.id.e2u_button);
assert e2u_button != null;
e2u_button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(balance >= 300){ //ERROR ON THIS LINE
}
}
});
final Button back_button = (Button) findViewById(R.id.back_button);
assert back_button != null;
back_button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(UpgradesActivity.this, MainActivity.class));
}
});
//TODO: Pass balance integer from MainActivity to here.
}
}
ALL ABOVE IS ANSWERED! ---------------------------------------------------------
Now i have problems with this part of the code:
#Override
public void onClick(View v) {
if(balance >= 300){
balance -= 300;
}
if(balance < 300){
final TextView text = (TextView) findViewById(R.id.not_enough_money_text);
assert text != null;
text.setText("You do not have enough money.");
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
#Override
public void run() {
text.setText("");
}
}, 2000);
}
}
When i click the button it says i do not have enough money but i have over 300. Please help me.
I found out what the problem was but I'm not sure how to fix it. I need to send balance back to MainActivity. Can anyone help with that?

Send the data like this -
UpgradesButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(MainActivity.this, UpgradesActivity.class);
intent.putExtra("key_int", balance);
startActivity(intent);
}
});
And fetch it in onCreate() of UpgradesActivity -
Intent mIntent = getIntent();
int intValue = mIntent.getIntExtra("key_int", 0);

You're using different key when sending and receiving the Int.
Change this line:
int intValue = mIntent.getIntExtra("intVariableName", 0);
To this:
int intValue = mIntent.getIntExtra("MyIntNameGoesHere", 0);

Android Eclipse - Buttons only open one after the other

I'm having a rather strange issue that I just can't solve.
I'm teaching myself Android Eclipse and I've created a very simple looking app with three buttons, 1)Facebook 2)LinkedIn and 3)Favourite Band. However, when I open the app on my phone, I can only press the buttons in order 1) --> 2) --> 3). For example, I can't open 2) unless i've already opened 1) and I can't open 3) unless I've already opened 2) etc. How can I change it so that I can open 3) first for example?
I've posted my java script below, any ideas would be great!
package tabletop.app4asli;
import android.app.Activity;
import android.content.Intent;
import android.media.MediaPlayer;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
public class MainActivity extends Activity {
MediaPlayer thesong;
Button main;
Button main2;
Button main3;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
main = (Button) findViewById(R.id.btn_go);
main.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String url = "https://www.facebook.com/asli.akidil?fref=ts";
Intent i = new Intent(Intent.ACTION_VIEW);
i.setData(Uri.parse(url));
startActivity(i);
main2 = (Button) findViewById(R.id.button2);
main2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String url = "https://www.linkedin.com/pub/asli-akidil/8a/719/55a.";
Intent i = new Intent(Intent.ACTION_VIEW);
i.setData(Uri.parse(url));
startActivity(i);
main3 = (Button) findViewById(R.id.button3);
main3.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String url = "http://www.biffyclyro.com";
Intent i = new Intent(Intent.ACTION_VIEW);
i.setData(Uri.parse(url));
startActivity(i);
}

It's because the code for the layout of button 2 is included in the onClick event of your button 1, and the layout of button 3 is included in the onClicked event of your button 2.
The code of onCreated() function should be looked like follows:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
main = (Button) findViewById(R.id.btn_go);
main.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String url = "https://www.facebook.com/asli.akidil?fref=ts";
Intent i = new Intent(Intent.ACTION_VIEW);
i.setData(Uri.parse(url));
startActivity(i);
}
});
main2 = (Button) findViewById(R.id.button2);
main2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String url = "https://www.linkedin.com/pub/asliakidil/8a/719/55a.";
Intent i = new Intent(Intent.ACTION_VIEW);
i.setData(Uri.parse(url));
startActivity(i);
}
});
main3 = (Button) findViewById(R.id.button3);
main3.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String url = "http://www.biffyclyro.com";
Intent i = new Intent(Intent.ACTION_VIEW);
i.setData(Uri.parse(url));
startActivity(i);
}
});
}

You are setting ClickListener for button 3 in the ClickListener of button 2 and ClickListener for button 2 in the ClickListener of button 1. So, button 2 and 3 won't initialize until button 1 and 2 are clicked respectively. You can set OnClickListener to all Buttons in a for loop like this:
ArrayList<Button> buttonList = new ArrayList<Button>();
buttonList.add((Button) findViewById(R.id.button1));
buttonList.add((Button) findViewById(R.id.button2));
buttonList.add((Button) findViewById(R.id.button3));
ArrayList<String> urlList = new ArrayList<String>();
urlList.add("https://www.facebook.com/asli.akidil?fref=ts");
urlList.add("https://www.linkedin.com/pub/asli-akidil/8a/719/55a.");
urlList.add("http://www.biffyclyro.com");
for (int i = 0; i < buttonList.size(); i++) {
final int index = i;
final Button button = buttonList.get(index);
final String url = urlList.get(index);
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
Intent i = new Intent(Intent.ACTION_VIEW);
i.setData(Uri.parse(url));
startActivity(i);
}
});
}

On button click switch to new layout xml file, using buttons now but how do I use fragments?

I am creating a Bluetooth app that requires a log in and/or sign up. I use a button click to switch to new layout xml file, but I need to not use buttons and figure out how to use fragments! When I have a button on the second page that gets clicked it crashes the app. Help :(
MainActivity.java
package com.example.chirp;
import android.app.Activity;
import android.app.FragmentTransaction;
import android.bluetooth.BluetoothAdapter;
import android.content.res.Configuration;
import android.os.Bundle;
import android.support.v4.app.FragmentManager;
import android.view.KeyEvent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
BluetoothAdapter bluetooth = BluetoothAdapter.getDefaultAdapter() ;
bluetooth.setName("Chirp Bluetooth");
String status; {
if (bluetooth != null)
{
if (bluetooth.isEnabled())
{
String mydeviceaddress = bluetooth.getAddress();
String mydevicename = bluetooth.getName();
// String state = bluetooth.getState();
// status = mydevicename + ":" + mydeviceaddress + ":" + state;
}
else
{
status = "Bluetooth is not Enabled.";
}
}
// Toast.makeText(this, status, Toast.LENGTH_LONG).show();
}
// Configuration config = getResources().getConfiguration();
//
// FragmentManager fragmentManager = getFragmentManager();
// FragmentTransaction fragmentTransaction =
// fragmentManager.beginTransaction();
//
Button quickfindbutton = (Button) findViewById(R.id.qfbutton);
quickfindbutton.setOnClickListener(new OnClickListener(){
public void onClick(View v){
}
});
Button loginbutton = (Button) findViewById(R.id.button1);
loginbutton.setOnClickListener(new OnClickListener(){
public void onClick(View v){
setContentView(R.layout.loginscreen);
};
});
Button signupbutton = (Button) findViewById(R.id.button2);
signupbutton.setOnClickListener(new OnClickListener(){
public void onClick(View v){
setContentView(R.layout.signupscreen);
}
});
// Button login = (Button) findViewById(R.id.login);
// login.setOnClickListener(new OnClickListener(){
// public void onClick(View v){
// setContentView(R.layout.devicepage);
// }
// });
}
public void showToast(String message) {
Toast toast = Toast.makeText(getApplicationContext(), message,
Toast.LENGTH_SHORT);
toast.show();
}
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {
setContentView(R.layout.activity_main);
return true;
}
return super.onKeyDown(keyCode, event);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
// public void newMessage(View v){
// Intent intent = new Intent(this,loginscreen.class);
// startActivity(intent);
// }
}

setContentView() should be in onCreate() method within first few lines. Otherwise it will not work. If you need to change the layout after click on the button what you can do is, use SharedPreferences.
Check the saved item in shared Preferences before and then use setContentView() method in onCreate(). Inside the button onClick () method save the wanted layout in SharedPreferences. Then write the code to restart the application.

Check out this link:
http://developer.android.com/guide/components/fragments.html
And also check if your second activity is registered in the manifest.xml.