EditText Username, Password;
Button login;
String username, password;
String login_url = "http://abc/api/UserLoginctrl";
AlertDialog.Builder builder;

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

    builder = new AlertDialog.Builder(MainActivity.this);

    Username = (EditText)findViewById(R.id.editText);
    Password = (EditText)findViewById(R.id.editText2);
    login = (Button)findViewById(R.id.button);

    login.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            username = Username.getText().toString();
            password = Password.getText().toString();

            if(username.equals("") || password.equals(""))
            {

                builder.setTitle("Something went wrong...");
                displayAlert("Enter valid credentials");
            }
            else
            {
                StringRequest stringRequest = new StringRequest(Request.Method.POST, login_url,
                        new Response.Listener<String>() {
                            @Override
                            public void onResponse(String response) {

                                try {
                                    JSONArray jsonArray = new JSONArray(response);
                                    JSONObject jsonObject = jsonArray.getJSONObject(0);
                                    String code = jsonObject.getString("code");
                                    if (code.equals("Login failed"))
                                    {
                                        builder.setTitle("Login Error..");
                                        displayAlert(jsonObject.getString("message"));
                                    }
                                    else
                                    {
                                        Intent intent = new Intent(MainActivity.this,LoginSuccess.class);
                                        Bundle bundle = new Bundle();

                                        bundle.putString("name", jsonObject.getString("name"));
                                        bundle.putString("email", jsonObject.getString("email"));
                                        intent.putExtras(bundle);
                                        startActivity(intent);
                                    }

                                } catch (JSONException e) {
                                    e.printStackTrace();
                                }

                            }
                        }, new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        Toast.makeText(MainActivity.this,"Erorrrrrr....",Toast.LENGTH_LONG).show();
                        error.printStackTrace();

                    }
                })
                {
                    @Override
                    protected Map<String, String> getParams() throws AuthFailureError {
                        Map<String, String> params = new HashMap<String, String>();
                        params.put("user_name", username);
                        params.put("password", password);

                        return params;
                    }
                };
                RequestQueue requestQueue = Volley.newRequestQueue(MainActivity.this);
                requestQueue.add(stringRequest);

            }
        }
    });

}
public void displayAlert(String message)
{
    builder.setMessage(message);
    builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialogInterface, int i) {

            Username.setText("");
            Password.setText("");
        }
    });
    AlertDialog alertDialog = builder.create();
    alertDialog.show();

}

TextView name, email;

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

    name = (TextView)findViewById(R.id.name);
    email = (TextView)findViewById(R.id.email);

    Bundle bundle = getIntent().getExtras();
    name.setText("Welcome" + bundle.getString("name"));
    email.setText("Email" + bundle.getString("email"));

}

<application

    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity android:name=".LoginSuccess"></activity>
</application>