webview back button stopped

Issue

In my webview app if I press the back button I get an error:

unfortunately app has stopped

I've tried 2 different ways of doing the back button. Am I missing something?

P.s. first app so please bear with me

package au.com.industryresponsetraining.mdt;

import android.content.Intent;
import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public class MainActivity extends AppCompatActivity {
    private WebView mwebview;

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

        String "http://www.google.com";
        WebView mwebview = (WebView) this.findViewById(R.id.webView);
        mwebview.getSettings().setJavaScriptEnabled(true);
        mwebview.loadUrl(url);
        mwebview.setWebViewClient(new WebViewClient());
    }

    private class MyWebviewClient extends WebViewClient {
        @Override
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            if (Uri.parse(url).getHost().equals("http://www.google.com")) {
                return false;
            } else {
                //here open external links in external browser or app
                Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
                startActivity(intent);
                return true;
            }

        }
    }
//back button function thats not working
    @Override
    public void onBackPressed() {
        if (mwebview.canGoBack()) {
            mwebview.goBack();
        } else {
            super.onBackPressed();
        }
    }
}

Solution

your onCreate method should be

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

    String "http://www.google.com";
    mwebview = (WebView) this.findViewById(R.id.webView);

}

instead of

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

    String "http://www.google.com";
    WebView mwebview = (WebView) this.findViewById(R.id.webView);

}

Answered By - curiousMind