How can i make this java working

IDE
2

try this code,

package jsr.tvdiscovery;

import com.google.appinventor.components.annotations.DesignerComponent;
import com.google.appinventor.components.runtime.AndroidNonvisibleComponent;
import com.google.appinventor.components.runtime.ComponentContainer;
import com.google.appinventor.components.annotations.SimpleFunction;

import android.os.Handler;
import android.os.Looper;

import com.google.appinventor.components.annotations.*;
import com.google.appinventor.components.common.ComponentCategory;
import com.google.appinventor.components.runtime.*;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketTimeoutException;

@DesignerComponent(
version = 1,
description = “Discover Smart TVs using SSDP”,
category = ComponentCategory.EXTENSION,
nonVisible = true,
iconName = “”
)
@SimpleObject(external = true)
public class TVDiscovery extends AndroidNonvisibleComponent {

private Handler uiHandler;

public TVDiscovery(ComponentContainer container) {
    super(container.$form());
    uiHandler = new Handler(Looper.getMainLooper());
}

@SimpleFunction(description = "Start searching for TVs on the network")
public void SearchTVs() {

    new Thread(new Runnable() {
        @Override
        public void run() {

            try {
                DatagramSocket socket = new DatagramSocket();
                socket.setSoTimeout(4000);

                String search =
                        "M-SEARCH * HTTP/1.1\r\n" +
                        "HOST: 239.255.255.250:1900\r\n" +
                        "MAN: \"ssdp:discover\"\r\n" +
                        "MX: 2\r\n" +
                        "ST: ssdp:all\r\n\r\n";

                DatagramPacket requestPacket = new DatagramPacket(
                        search.getBytes(),
                        search.length(),
                        InetAddress.getByName("239.255.255.250"),
                        1900
                );

                socket.send(requestPacket);

                byte[] buffer = new byte[2048];
                DatagramPacket responsePacket = new DatagramPacket(buffer, buffer.length);

                while (true) {
                    try {
                        socket.receive(responsePacket);

                        final String response = new String(
                                responsePacket.getData(),
                                0,
                                responsePacket.getLength()
                        );

                        final String ip = responsePacket.getAddress().getHostAddress();

                        // Simple filter for TVs
                        if (response.toLowerCase().contains("tv") ||
                            response.toLowerCase().contains("mediarenderer")) {

                            uiHandler.post(new Runnable() {
                                @Override
                                public void run() {
                                    TVFound(ip, ExtractName(response));
                                }
                            });
                        }

                    } catch (SocketTimeoutException e) {
                        break;
                    }
                }

                socket.close();

                uiHandler.post(new Runnable() {
                    @Override
                    public void run() {
                        SearchFinished();
                    }
                });

            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }).start();
}

// Extract friendly name from response (basic)
private String ExtractName(String response) {
    try {
        String lower = response.toLowerCase();

        if (lower.contains("server:")) {
            int start = lower.indexOf("server:");
            int end = response.indexOf("\n", start);
            return response.substring(start + 7, end).trim();
        }

    } catch (Exception ignored) {}

    return "Smart TV";
}

@SimpleEvent(description = "Triggered when a TV is found")
public void TVFound(String tvIP, String tvName) {
    EventDispatcher.dispatchEvent(this, "TVFound", tvIP, tvName);
}

@SimpleEvent(description = "Triggered when search is finished")
public void SearchFinished() {
    EventDispatcher.dispatchEvent(this, "SearchFinished");
}

}

jsr.tvdiscovery.aix (6.5 KB)

this was compiled by FAST-CLI and credit to @JEWEL