I'm working on a register page and i got this problems(as what is shown in the picture)[screenshot of the problem]: https://i.stack.imgur.com/q3rA0.jpg. I'm new to php and online database so i hope you can bear with me. I'm using xampp as my server.
Here's my android studio code:
public class MainActivity extends AppCompatActivity {
// Creating EditText.
EditText FirstName, LastName, Email ;
// Creating button;
Button InsertButton;
// Creating Volley RequestQueue.
RequestQueue requestQueue;
// Create string variable to hold the EditText Value.
String FirstNameHolder, LastNameHolder, EmailHolder ;
// Creating Progress dialog.
ProgressDialog progressDialog;
// Storing server url into String variable.
String HttpUrl = "http://192.168.254.254:81/connection/insert_record.php";
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    // Assigning ID's to EditText.
    FirstName = (EditText) findViewById(R.id.editTextFirstName);
    LastName = (EditText) findViewById(R.id.editTextLastName);
    Email = (EditText) findViewById(R.id.editTextEmail);
    // Assigning ID's to Button.
    InsertButton = (Button) findViewById(R.id.ButtonInsert);
    // Creating Volley newRequestQueue .
    requestQueue = Volley.newRequestQueue(MainActivity.this);
    progressDialog = new ProgressDialog(MainActivity.this);
    // Adding click listener to button.
    InsertButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            // Showing progress dialog at user registration time.
            progressDialog.setMessage("Please Wait, We are Inserting Your Data on Server");
            progressDialog.show();
            // Calling method to get value from EditText.
            GetValueFromEditText();
            // Creating string request with post method.
            StringRequest stringRequest = new StringRequest(Request.Method.POST, HttpUrl,
                    new Response.Listener<String>() {
                        @Override
                        public void onResponse(String ServerResponse) {
                            // Hiding the progress dialog after all task complete.
                            progressDialog.dismiss();
                            // Showing response message coming from server.
                            Toast.makeText(MainActivity.this, ServerResponse, Toast.LENGTH_LONG).show();
                        }
                    },
                    new Response.ErrorListener() {
                        @Override
                        public void onErrorResponse(VolleyError volleyError) {
                            // Hiding the progress dialog after all task complete.
                            progressDialog.dismiss();
                            // Showing error message if something goes wrong.
                            Toast.makeText(MainActivity.this, volleyError.toString(), Toast.LENGTH_LONG).show();
                        }
                    }) {
                @Override
                protected Map<String, String> getParams() {
                    // Creating Map String Params.
                    Map<String, String> params = new HashMap<String, String>();
                    // Adding All values to Params.
                    params.put("first_name", FirstNameHolder);
                    params.put("last_name", LastNameHolder);
                    params.put("email", EmailHolder);
                    return params;
                }
            };
            // Creating RequestQueue.
            RequestQueue requestQueue = Volley.newRequestQueue(MainActivity.this);
            // Adding the StringRequest object into requestQueue.
            requestQueue.add(stringRequest);
        }
    });
}
// Creating method to get value from EditText.
public void GetValueFromEditText(){
    FirstNameHolder = FirstName.getText().toString().trim();
    LastNameHolder = LastName.getText().toString().trim();
    EmailHolder = Email.getText().toString().trim();
}
And here's my php code:
Insert_record.php
<?php
include 'DatabaseConfig.php';
$con = mysqli_connect($HostName,$HostUser,$HostPass,$DatabaseName);
$f_name = $_POST['first_name'];
$l_name = $_POST['last_name'];
$email = $_POST['email'];
$Sql_Query = "insert into UserInfo (first_name,last_name,email) values 
('$f_name','$l_name','$email')";
if(mysqli_query($con,$Sql_Query)){
echo 'Data Inserted Successfully';
}
else{
echo 'Try Again';
}
mysqli_close($con);
?>
Dataconfig.php
<?php
$HostName = "localhost";
$HostUser = "root";
$HostPass = "root";
$DatabaseName = "users";
?>
 
    