MainActivity.java

package com.iot.climateedge.connection;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;

public class MainActivity extends AppCompatActivity {

    Button button;
    TextView textView;
    String server_url = "http://129.31.178.216/greetings.php"; //change url and php filename here

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button = (Button)findViewById(R.id.bn);
        textView = (TextView)findViewById(R.id.txt);
        button.setOnClickListener(new View.OnClickListener() {

            public void onClick(View v){

                final RequestQueue requestQueue = Volley.newRequestQueue(MainActivity.this);

                StringRequest stringRequest = new StringRequest(Request.Method.POST, server_url,
                        new Response.Listener<String>() {
                            @Override
                            public void onResponse(String response) {

                                textView.setText(response);
                                requestQueue.stop();

                            }
                        }, new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {

                        textView.setText("Something went wrong...");
                        error.printStackTrace();
                        requestQueue.stop();

                    }
                });
                requestQueue.add(stringRequest);
            }
        });
    }
}