Android Studio: How to send data from Activity to Fragment | Method invocation 'getString' may produce 'NullPointerException' - android-studio

Question

I am having a problem where in the Fragment the "getString()" says "Method invocation 'getString' may produce 'NullPointerException'" that's the only problem. The Fragment is stored in MainActivity in Navigation Window.
LoginActivity (Where MainActivity is getting the Data):
private void LoginMethod(String email, String password) {
StringRequest stringRequest = new StringRequest(Request.Method.POST, URL, new Response.Listener() {
#Override
public void onResponse(String response) {
try {
JSONObject jsonObject = new JSONObject(response);
String result = jsonObject.getString("success");
JSONArray jsonArray = jsonObject.getJSONArray("login");
if (result.equals("1")){
for (int i = 0; i < jsonArray.length(); i++){
JSONObject object = jsonArray.getJSONObject(i);
String username = object.getString("Username").trim();
String email = object.getString("Email").trim();
Toast.makeText(Login.this, "Login Success: " + username, Toast.LENGTH_SHORT).show();
Intent intent = new Intent(Login.this, MainActivity.class);
intent.putExtra("username", username);
intent.putExtra("email", email);
startActivity(intent);
}
}
else if (result.equals("0")) {
Toast.makeText(Login.this, "Login Failed" + result + response, Toast.LENGTH_LONG).show(); Log.e("JSON Error", response);
Log.e("Login Error", result);
}
}
catch (JSONException e){
Toast.makeText(Login.this, e.getMessage(), Toast.LENGTH_LONG).show();
Log.e("JSON Error", response);
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(Login.this, error.getMessage(), Toast.LENGTH_SHORT).show();
}
})
{
#Override
protected Map<String, String> getParams() throws AuthFailureError {
Map<String, String> params = new HashMap<>();
params.put("Email", email);
params.put("Password", password);
return params;
}
};
RequestQueue requestQueue = Volley.newRequestQueue(this);
requestQueue.add(stringRequest);
}
**MainActivity:**
public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {
Toolbar toolbar;
TextView getemail, getusername;
DrawerLayout drawerLayout;
NavigationView navigationView;
View navheader;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.i("State","onCreate");
toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
drawerLayout = findViewById(R.id.drawerLayout);
navigationView = findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
navheader = navigationView.getHeaderView(0);
String getUsername = getIntent().getStringExtra("username");
String getEmail = getIntent().getStringExtra("email");
getusername = navheader.findViewById(R.id.getusername);
getemail = navheader.findViewById(R.id.getemail);
toolbar.setTitle(getUsername);
getusername.setText(getUsername);
getemail.setText(getEmail);
ActionBarDrawerToggle actionBarDrawerToggle = new ActionBarDrawerToggle(this, drawerLayout, toolbar,
R.string.nav_drawer_open, R.string.nav_drawer_close);
drawerLayout.addDrawerListener(actionBarDrawerToggle);
actionBarDrawerToggle.syncState();
if (savedInstanceState == null){
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
new Home()).commit();
navigationView.setCheckedItem(R.id.home);
}
}
public void getAccountFragmentData(){
String test = "akshdasjkdhsajkdasdas";
String test2 = "wadahawawaawaww";
Bundle bundle = new Bundle();
bundle.putString("username", test);
bundle.putString("email", test2);
Account account = new Account();
account.setArguments(bundle);
Toast.makeText(this, "Account", Toast.LENGTH_SHORT).show();
}
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
switch (item.getItemId()){
case R.id.home:
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
new Home()).commit();
break;
case R.id.orderfood:
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
new FoodOrder()).commit();
break;
case R.id.account:
getAccountFragmentData();
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
new Account()).commit();
break;
case R.id.settings:
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
new Settings()).commit();
break;
case R.id.email:
Toast.makeText(this, "Email", Toast.LENGTH_SHORT).show();
break;
case R.id.share:
Toast.makeText(this, "Share", Toast.LENGTH_SHORT).show();
break;
}
drawerLayout.closeDrawer(GravityCompat.START);
return true;
}
#Override
public void onBackPressed() {
if (drawerLayout.isDrawerOpen(GravityCompat.START)){
drawerLayout.closeDrawer(GravityCompat.START);
}
else {
super.onBackPressed();
}
}
#Override
protected void onStart() {
super.onStart();
Log.i("State","onStart");
}
#Override
protected void onResume() {
super.onResume();
Log.i("State","onResume");
}
#Override
protected void onPause() {
super.onPause();
Log.i("State","onPause");
}
#Override
protected void onStop() {
super.onStop();
Log.i("State","onStop");
}
#Override
protected void onRestart() {
super.onRestart();
Log.i("State","onRestart");
}
#Override
protected void onDestroy() {
super.onDestroy();
Log.i("State","onDestroy");
}
}
**Fragment:
**
public class Account extends Fragment {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View v = inflater.inflate(R.layout.fragment_account, container, false);
TextView getUsername = v.findViewById(R.id.username);
TextView getEmail = v.findViewById(R.id.email);
Bundle bundle = this.getArguments();
String setUsername = bundle.getString("username");
String setEmail = bundle.getString("email");
getUsername.setText(setUsername);
getEmail.setText(setEmail);
Log.i("Data Sent", "Sent");
return v;
}
I want the Fragment to get the data from MainActivity.