Join SwipeRefreshLayout; Post compiled program. Open error flashing. Here is my source code

Question

<LinearLayout

xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:app="http://schemas.android.com/apk/res-auto"

android:layout_width="match_parent"



android:layout_height="match_parent"

android:orientation="vertical">



<WebView

    android:id="@+id/webview"

    

    android:layout_width="match_parent"

    

    android:layout_height="match_parent"/>

package guidong.dengyaoping;

import android.os.Bundle;

import androidx.appcompat.app.AppCompatActivity;

import androidx.appcompat.widget.Toolbar;

import android.os.Bundle;

import android.app.Activity;

import android.os.Bundle;

import android.view.View;

import android.webkit.JavascriptInterface;

import android.view.View.OnClickListener;

import android.webkit.WebSettings;

import android.webkit.WebView;

import android.webkit.WebViewClient;

import android.widget.Button;

import android.widget.EditText;

import android.widget.LinearLayout;

import android.app.*;

import android.os.*;

import android.view.*;

import android.content.*;

import androidx.swiperefreshlayout.widget.SwipeRefreshLayout;

public class MainActivity extends Activity {

private WebView webView;

SwipeRefreshLayout swipeRefreshLayout;

@Override

protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_main);



    webView = findViewById(R.id.webview);



    webView.getSettings().setJavaScriptEnabled(true);//让WebView支持JavaScript脚本



    

  

    webView.setWebViewClient(new WebViewClient(){



            public void onReceivedError(WebView view, int errorCode,

                                        String description, String failingUrl) {

                //用javascript自定义错误界面

                String data = "无网络，捐赠加开发者;邓耀平。微信13662869825";

                view.loadUrl("javascript:document.body.innerHTML=\"" + data + "\"");

            }



            @Override

            public boolean shouldOverrideUrlLoading(WebView view, String url) {

                https://hhk.9a07q.com/

                view.loadUrl(url);//根据传入的参数去加载新网页

                return true;//表示当前WebView可以处理新打开的网页，不用借助系统浏览器



            }



        });



    webView.loadUrl(" http://124.70.8.80:8730/" );

    this.webView.setInitialScale(166);

swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {

@Override

public void onRefresh() {

    //这里获取数据的逻辑

    swipeRefreshLayout.setRefreshing(true);

}

});

}

}