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Sending and Receiving Data with Sockets in android

Android Apps/Applications Mobile Development

This example demonstrate about Sending and Receiving Data with Sockets in android

Need Server and Client Project

Server

Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.

Step 2 − Add the following code to res/layout/activity_main.xml.

Step 3 − Add the following code to src/MainActivity.java

package com.server.myapplication.server;
import android.annotation.SuppressLint;
import android.net.wifi.WifiInfo;
import android.net.wifi.WifiManager;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.UnknownHostException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;

@SuppressLint("SetTextI18n")
public class MainActivity extends AppCompatActivity {
   ServerSocket serverSocket;
   Thread Thread1 = null;
   TextView tvIP, tvPort;
   TextView tvMessages;
   EditText etMessage;
   Button btnSend;
   public static String SERVER_IP = "";
   public static final int SERVER_PORT = 8080;
   String message;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      tvIP = findViewById(R.id.tvIP);
      tvPort = findViewById(R.id.tvPort);
      tvMessages = findViewById(R.id.tvMessages);
      etMessage = findViewById(R.id.etMessage);
      btnSend = findViewById(R.id.btnSend);
      try {
         SERVER_IP = getLocalIpAddress();
      } catch (UnknownHostException e) {
         e.printStackTrace();
      }
      Thread1 = new Thread(new Thread1());
      Thread1.start();
      btnSend.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            message = etMessage.getText().toString().trim();
            if (!message.isEmpty()) {
               new Thread(new Thread3(message)).start();
            }
         }
      });
   }
   private String getLocalIpAddress() throws UnknownHostException {
      WifiManager wifiManager = (WifiManager) getApplicationContext().getSystemService(WIFI_SERVICE);
      assert wifiManager ! = null;
      WifiInfo wifiInfo = wifiManager.getConnectionInfo();
      int ipInt = wifiInfo.getIpAddress();
      return InetAddress.getByAddress(ByteBuffer.allocate(4).order(ByteOrder.LITTLE_ENDIAN).putInt(ipInt).array()).getHostAddress();
   }
   private PrintWriter output;
   private BufferedReader input;
   class Thread1 implements Runnable {
      @Override
      public void run() {
         Socket socket;
         try {
            serverSocket = new ServerSocket(SERVER_PORT);
            runOnUiThread(new Runnable() {
               @Override
               public void run() {
                  tvMessages.setText("Not connected");
                  tvIP.setText("IP: " + SERVER_IP);
                  tvPort.setText("Port: " + String.valueOf(SERVER_PORT));
               }
            });
            try {
               socket = serverSocket.accept();
               output = new PrintWriter(socket.getOutputStream());
               input = new BufferedReader(new InputStreamReader(socket.getInputStream()));
               runOnUiThread(new Runnable() {
                  @Override
                  public void run() {
                     tvMessages.setText("Connected
");
                  }
               });
               new Thread(new Thread2()).start();
            } catch (IOException e) {
               e.printStackTrace();
            }
         } catch (IOException e) {
            e.printStackTrace();
         }
      }
   }
   private class Thread2 implements Runnable {
      @Override
      public void run() {
         while (true) {
            try {
               final String message = input.readLine();
               if (message ! = null) {
                  runOnUiThread(new Runnable() {
                     @Override
                     public void run() {
                        tvMessages.append("client:" + message + "
");
                     }
                  });
               } else {
                  Thread1 = new Thread(new Thread1());
                  Thread1.start();
                  return;
               }
            } catch (IOException e) {
               e.printStackTrace();
            }
         }  
      }
   }
   class Thread3 implements Runnable {
      private String message;
      Thread3(String message) {
         this.message = message;
      }
      @Override
      public void run() {
         output.write(message);
         output.flush();
         runOnUiThread(new Runnable() {
            @Override
            public void run() {
               tvMessages.append("server: " + message + "
");
               etMessage.setText("");
            }
         });
      }
   }
}

Step 4 − Add the following code to androidManifest.xml

Client

Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.

Step 2 − Add the following code to res/layout/activity_main.xml.

Step 3 − Add the following code to res/layout/MainActivity.java.

package com.client.myapplication.client;
import android.annotation.SuppressLint;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;

@SuppressLint("SetTextI18n")
public class MainActivity extends AppCompatActivity {
   Thread Thread1 = null;
   EditText etIP, etPort;
   TextView tvMessages;
   EditText etMessage;
   Button btnSend;
   String SERVER_IP;
   int SERVER_PORT;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      etIP = findViewById(R.id.etIP);
      etPort = findViewById(R.id.etPort);
      tvMessages = findViewById(R.id.tvMessages);
      etMessage = findViewById(R.id.etMessage);
      btnSend = findViewById(R.id.btnSend);
      Button btnConnect = findViewById(R.id.btnConnect);
      btnConnect.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            tvMessages.setText("");
            SERVER_IP = etIP.getText().toString().trim();
            SERVER_PORT = Integer.parseInt(etPort.getText().toString().trim());
            Thread1 = new Thread(new Thread1());
            Thread1.start();
         }
      });
      btnSend.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            String message = etMessage.getText().toString().trim();
            if (!message.isEmpty()) {
               new Thread(new Thread3(message)).start();
            }
         }
      });
   }
   private PrintWriter output;
   private BufferedReader input;
   class Thread1 implements Runnable {
      public void run() {
         Socket socket;
         try {
            socket = new Socket(SERVER_IP, SERVER_PORT);
            output = new PrintWriter(socket.getOutputStream());
            input = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            runOnUiThread(new Runnable() {
               @Override
               public void run() {
                  tvMessages.setText("Connected
");
               }
            });
            new Thread(new Thread2()).start();
         } catch (IOException e) {
         e.printStackTrace();
         }
      }
   }
   class Thread2 implements Runnable {
      @Override
      public void run() {
         while (true) {
            try {
               final String message = input.readLine();
               if (message ! = null) {
                  runOnUiThread(new Runnable() {
                     @Override
                     public void run() {
                        tvMessages.append("server: " + message + "
");
                     }
                  });
               } else {
                  Thread1 = new Thread(new Thread1());
                  Thread1.start();
                  return;
               }
            } catch (IOException e) {
               e.printStackTrace();
            }
         }
      }
   }
   class Thread3 implements Runnable {
      private String message;
      Thread3(String message) {
         this.message = message;
      }
      @Override
      public void run() {
         output.write(message);
         output.flush();
         runOnUiThread(new Runnable() {  
            @Override
            public void run() {
               tvMessages.append("client: " + message + "
");
               etMessage.setText("");
            }
         });
      }
   }
}

Step 4 − Add the following code to androidManifest.xml

Let's try to run your both server and client application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click Run icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen –