我想开发浏览器应用程序，但出现错误

Question

I am new to Android I want to develop a browser app now I am trying to develop it, in this I am getting errors. I tried in another method also on that it's asking on which browser you have to open like that but for me I want to open in my app only.

WebviewActivity.java

package com.example.admin.fristapp;

import android.app.Activity;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.webkit.WebResourceRequest;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public class WebviewActivity extends Activity {
    WebView webview1;
   // String url = "http://www.google.com";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_webview);
        webview1 = (WebView) findViewById(R.id.webview1);
      //  webview1.loadUrl(url);

        //MyBrowser my ;

        new Background().execute();


    }

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




    public class Background extends AsyncTask<String,String,String>
    {
        @Override
        protected void onPostExecute(String s)
        {
            super.onPostExecute(s);
        }
        @Override
        protected void onPreExecute()
        {
            super.onPreExecute();
        }

        @Override
        protected String doInBackground(String... strings)
        {
            search();
            return null;
        }
    }
    public void search()
    {
        webview1.setWebViewClient(new WebviewActivity.MyBrowser());
        String url = "http://www.google.com";
        webview1.getSettings().setJavaScriptEnabled(true);
        webview1.loadUrl(url);
    }
}

logcat

java.lang.Throwable: A WebView method was called on thread 'AsyncTask #4'. All WebView methods must be called on the same thread. (Expected Looper Looper (main, tid 1) {180a245b} called on null, FYI main Looper is Looper (main, tid 1) {180a245b})
                                                                            at android.webkit.WebView.checkThread(WebView.java:2290)

Afteredit

import android.app.Activity;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.webkit.WebResourceRequest;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public class WebviewActivity extends Activity {
    WebView webview;
    String url = "http://www.google.com";

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

        webview =(WebView )findViewById(R.id.webview1);
                //WebView(WebviewActivity.this);
        webview.loadUrl(url);

        webview.setWebViewClient(new WebViewClient() {
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url) {
                view.loadUrl(url);
                return false;
            }

            @Override
            public void onPageFinished(WebView view, String url) {
                super.onPageFinished(view, url);

                // Do your code when page finished
            }
        });

Answer 1

Your are loading a url in WebView in doInBackground() method. You should do on the UI thread.

loadUrl() is already doing everything asynchronously. So no need to of AsyncTask . Move your code in onCreate() method.

If you want to display a loading indicator, you need to use as below :

WebView webview = new WebView(MainActivity.this);

webview.setWebViewClient(new WebViewClient() {
    @Override
    public boolean shouldOverrideUrlLoading(WebView view, String url) {    
        view.loadUrl(url);    
         return false;
    }

    @Override
    public void onPageFinished(WebView view, String url) {
           super.onPageFinished(view, url);

           // Do your code when page finished
     }
});

webview.loadUrl(url);