RegisterActivity.java

package zcode.learn.loginandregister;

import android.content.Intent;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.toolbox.JsonArrayRequest;
import com.android.volley.toolbox.Volley;

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

public class RegisterActivity extends AppCompatActivity {

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

        final AlertDialog.Builder builder = new AlertDialog.Builder(RegisterActivity.this);

        final EditText etName = (EditText) findViewById(R.id.etName);
        final EditText etAge = (EditText) findViewById(R.id.etAge);
        final EditText etUsername = (EditText) findViewById(R.id.etUsername);
        final EditText etPassword = (EditText) findViewById(R.id.etPassword);
        final Button bRegister = (Button) findViewById(R.id.bRegister);

        if (bRegister != null) {
            bRegister.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    final String name = etName.getText().toString();
                    final String age = etAge.getText().toString();
                    final String username = etUsername.getText().toString();
                    final String password = etPassword.getText().toString();

                    if (name != "" && age != "" && username != "" && password != "") {
                        Response.Listener<String> responseListener = new Response.Listener<String>() {
                            @Override
                            public void onResponse(String response) {
                                JSONObject jsonObject = null;
                                try {
                                    jsonObject = new JSONObject(response);
                                    boolean success = jsonObject.getBoolean("success");
                                    if (success) {
                                        Intent intent = new Intent(RegisterActivity.this, LoginActivity.class);
                                        RegisterActivity.this.startActivity(intent);
                                    } else {
                                        builder.setMessage("Something wrong, please try again")
                                                .setNegativeButton("Retry", null)
                                                .create()
                                                .show();
                                    }
                                }
                                catch (JSONException e) {
                                    e.printStackTrace();
                                }

                            }
                        };
                        RegisterRequest registerRequest = new RegisterRequest(name, age, username, password, responseListener);

                        RequestQueue requestQueue = Volley.newRequestQueue(RegisterActivity.this);
                        requestQueue.add(registerRequest);
                    } else {
                        builder.setMessage("Please fill the text field")
                                .setNegativeButton("Ok", null)
                                .create()
                                .show();
                    }
                }
            });
        }
    }
}