Android Studio Upload Multiple files

I am trying to make an upload file system I already made a single file upload, and I can’t turn it to multiple file upload help, please!

My MainActivity.java file

    package com.example.photodel;



    import java.util.concurrent.Executors;
    import java.util.concurrent.ScheduledExecutorService;
    import java.util.concurrent.TimeUnit;
    import android.Manifest;
    import android.app.Activity;
    import android.app.AlertDialog;
    import android.content.ActivityNotFoundException;
    import android.content.Context;
    import android.content.DialogInterface;
    import android.content.Intent;
    import android.net.Uri;
    import android.os.AsyncTask;
    import android.os.Build;
    import android.os.Bundle;
    import android.util.Log;
    import android.view.KeyEvent;
    import android.view.ViewGroup;
    import android.webkit.ValueCallback;
    import android.webkit.WebChromeClient;
    import android.webkit.WebView;
    import android.webkit.WebViewClient;
    import android.widget.FrameLayout;
    import android.view.View;
    import android.widget.Toast;


    import androidx.annotation.RequiresApi;
    import androidx.appcompat.app.AppCompatActivity;




    public class MainActivity extends AppCompatActivity {


        WebView webView;
        private ValueCallback<Uri> mUploadMessage;
        public ValueCallback<Uri[]> uploadMessage;
        public static final int REQUEST_SELECT_FILE = 100;
        private final static int FILECHOOSER_RESULTCODE = 1;

        public String url ="https://photodel.finalescaperobl.repl.co";


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



            webView = (WebView) findViewById(R.id.web_view);
            webView.getSettings().setJavaScriptEnabled(true);
            webView.loadUrl(url);









            webView.setWebViewClient(new xWebViewClient());
            webView.setWebChromeClient(new WebChromeClient() {

                public boolean onShowFileChooser(WebView mWebView, ValueCallback<Uri[]> filePathCallback, WebChromeClient.FileChooserParams fileChooserParams) {
                    uploadMessage = filePathCallback;

                    Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
                    intent.setType("*/*");
                    intent.putExtra(Intent.EXTRA_ALLOW_MULTIPLE, true);
                    intent.addCategory(Intent.CATEGORY_DEFAULT  );
                    startActivityForResult(Intent.createChooser(intent, "File Browser"), REQUEST_SELECT_FILE);
                    return true;
                }


            });







        }

        public class MyWebViewClient extends WebViewClient {
            private Context context;

            public MyWebViewClient(Context context) {
                this.context = context;
            }

            @Override
            public void onPageFinished(WebView view, String url) {
                String webUrl = webView.getUrl();
                if (webUrl.contains("alert")) {
                    System.out.println("Hello ");
                    Toast.makeText(context, "URL is AMOGASSAS123", Toast.LENGTH_LONG).show();
                }
            }
        }

        @Override
        protected void onActivityResult(int requestCode, int resultCode, Intent intent) {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                if (requestCode == REQUEST_SELECT_FILE) {
                    if (uploadMessage == null)
                        return;
                    uploadMessage.onReceiveValue(WebChromeClient.FileChooserParams.parseResult(resultCode, intent));
                    uploadMessage = null;
                }
            } else if (requestCode == FILECHOOSER_RESULTCODE) {
                if (null == mUploadMessage)
                    return;
                // Use MainActivity.RESULT_OK if you're implementing WebView inside Fragment
                // Use RESULT_OK only if you're implementing WebView inside an Activity
                Uri result = intent == null || resultCode != MainActivity.RESULT_OK ? null : intent.getData();
                mUploadMessage.onReceiveValue(result);
                mUploadMessage = null;
            }
            super.onActivityResult(requestCode, resultCode, intent);
        }




        private class xWebViewClient extends WebViewClient {
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url) {
                view.loadUrl(url);
                return true;
            }
        }


        @Override
        public boolean onKeyDown(int keyCode, KeyEvent event) {

            if (keyCode == KeyEvent.KEYCODE_BACK && webView.canGoBack()) {
                webView.goBack();
                return true;
            }

            return super.onKeyDown(keyCode, event);
        }






    }

I was trying to make an application that deletes multiple photos. Because I don’t know java I added a web view to display my node.js site. So i need to make a file chooser that chooses multiple files.