Comment combiner deux fonctions ensemble dans Java Android

Comment puis-je être capable de combiner ces deux fonctions en une seule et de pouvoir effectuer deux actions Invisible et invisible. Je ne veux pas simplement obtenir la déclaration if de la méthode buttonInVisible et simplement la mettre dans la commande buttonVisible.

Voici le code

Activité principale

import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends FragmentActivity {

    private WebViewFragment mWebViewFragment;
    public TextView textView;
    public Button buttons;

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

        buttons = (Button) findViewById(R.id.button);
        buttons.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                onBackPressed();
            }
        });
        textView = (TextView) findViewById(R.id.textViewId);
        FragmentManager fragmentManager = getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

        mWebViewFragment = new WebViewFragment();
        fragmentTransaction.replace(R.id.mainFragment, mWebViewFragment);
        fragmentTransaction.commit();
    }

    @Override
    public void onBackPressed() {

        if(mWebViewFragment != null && mWebViewFragment.canGoBack()) {
            mWebViewFragment.goBack();
        } else {
            super.onBackPressed();
        }
    }

    public void setTitle(String title) {
        if(textView != null){
            textView.setText(title);
        }
    }

    public void buttonVisible(int visibility) {
        if(buttons != null){
            buttons.setVisibility(visibility);
        }
    }

    @Override
    protected void onStart() {
        super.onStart();
        setVisible(true);
    }
}

Fragment

import android.app.Activity;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public class WebViewFragment extends Fragment {

    private WebView mWebView;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_main, container, false);
        mWebView = (WebView) view.findViewById(R.id.webView);
        WebSettings webSettings = mWebView.getSettings();
        webSettings.setJavaScriptEnabled(true);
        mWebView.loadUrl("https://www.google.co.uk/");
        mWebView.setWebViewClient(new WebViewClient() {
            @Override
            public void onPageStarted(WebView view, String url, Bitmap favicon) {
                super.onPageStarted(view, url, favicon);
                Log.v("WebView has started", url);
            }

            @Override
            public void onPageFinished(WebView view, String url) {
                String title = mWebView.getTitle();
                Log.v(getClass().getName(), "Title=" + title);
                /**if(mWebView.canGoBack()) {
                    buttonVisible();
                } else {
                    buttonInVisible();
                }**/
            }
        });

        mWebView.setWebChromeClient(new WebChromeClient() {
            @Override
            public void onReceivedTitle(WebView view, String title) {
                super.onReceivedTitle(view, title);
                    setTitle(title);
                Log.v(getClass().getName(), "Received Title" + title);
            }
        });
        return view;
    }

    public boolean canGoBack() {
        return mWebView.canGoBack();
    }

    public void goBack() {
        mWebView.goBack();
    }

    public void setTitle(String title) {

        if (title != null && title.length() > 0) {
            Activity activity = getActivity();
            if(activity != null && activity instanceof MainActivity){
                ((MainActivity) activity).setTitle(title);
            }
        }
    }

   public void SetVibility() {
       Activity activity = getActivity();
       if(activity != null && activity instanceof MainActivity) {
           ((MainActivity) activity).buttonVisible(View.VISIBLE);
       }
   }

    public void buttonInVisible() {
        Activity activity = getActivity();
        if(activity != null && activity instanceof MainActivity){
            ((MainActivity) activity).buttonVisible(View.INVISIBLE);
        }
    }
}