Android TCP Socket Client

A minimal Android app (Java) that opens a TCP socket to a server on the local network, sends a line of text, and shows the server's one-line reply in a toast. Written as the client side of a networking course milestone (project name mileston0).

Features

• Connect button opens a java.net.Socket to a hard-coded host and port (192.168.43.226:8888).
• Send button writes the text from the input field followed by a newline (DataOutputStream.writeBytes), then reads one line back (BufferedReader.readLine) and displays it as FROM SERVER: <reply>.

The server is not part of this repository; any TCP server that reads a line and answers with a line will work.

Known Limitations

• Socket connect, send and receive run on the UI thread. Android blocks network calls on the main thread by default (NetworkOnMainThreadException), so they would need to move to a background thread for the app to work on current Android versions.
• Host and port are hard-coded in client.java.

Tech Stack

• Java, Android SDK (compileSdk/targetSdk 32, minSdk 28)
• Android Support Library (appcompat-v7, constraint-layout)
• java.net.Socket (TCP)

Repository Contents

app/
├── build.gradle
└── src/main/
    ├── AndroidManifest.xml                     # INTERNET + ACCESS_NETWORK_STATE permissions
    ├── java/com/example/mileston0/client.java  # the only activity
    └── res/layout/activity_main.xml            # text field, "connect" and "send" buttons

How to Run

1. Start a line-based TCP server on a machine in the same network.
2. Change hostName and portNumber in client.java to match it.
3. Open the project in Android Studio and run it on a device on that network; tap connect, type a message, tap send.

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Developed by Khaled Walid