在片段中制作 onBackPressed

Question

How to change code below of activity to the code in Fragment? This is Android Studio code. My page now is Fragment, I want use this code and i want modified to fragment code. If who know, tell me, thanks. And I also put my current code in fragment and the activity connect with fragment.

Fragment Code:

public class Tab1Fragment extends Fragment {
Context mContext;

public WebView webView;


@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.tab1_fragment, container, false);
     mContext = view.getContext();                                             
    webView = (WebView) view.findViewById(R.id.webview);
    WebSettings webSettings = webView.getSettings();
    webSettings.setJavaScriptEnabled(true);
    webView.setInitialScale(1);
    webView.getSettings().setLoadWithOverviewMode(true);
    webView.getSettings().setUseWideViewPort(true);
    webView.setScrollBarStyle(WebView.SCROLLBARS_OUTSIDE_OVERLAY);
    webView.setScrollbarFadingEnabled(false);
    webView.getSettings().setBuiltInZoomControls(true);
    webView.loadUrl("https://www.facebook.com/");
    webView.setWebViewClient(new WebViewClient());

    return view;

}
}

Activity code:

public class Schedule extends AppCompatActivity {

private static final String TAG = "Schedule";
private SectionsPagerAdapter mSectionsPagerAdapter;

/**
 * The {@link ViewPager} that will host the section contents.
 */
private ViewPager mViewPager;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.schedule);
    Log.d(TAG, "onCreate: Starting.");
    initialiseView();
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    TextView mTitle = (TextView) toolbar.findViewById(R.id.toolbar_title);
    setSupportActionBar(toolbar);
    toolbar.setTitle("SCHEDULE");
    mTitle.setText(toolbar.getTitle());
    getSupportActionBar().setDisplayShowTitleEnabled(false);
    if(getSupportActionBar() !=null){
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setDisplayShowHomeEnabled(true);
    }


    // Create the adapter that will return a fragment for each of the three
    // primary sections of the activity.
    mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

    // Set up the ViewPager with the sections adapter.
    mViewPager = (ViewPager) findViewById(R.id.container);
    mViewPager.setAdapter(mSectionsPagerAdapter);
    setupViewPager(mViewPager);
    TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
    tabLayout.setupWithViewPager(mViewPager);

}
private void setupViewPager(ViewPager viewPager){
    SectionPageAdapter adapter = new SectionPageAdapter(getSupportFragmentManager());
    adapter.addFragment(new Tab1Fragment(), "4 Sept 2018");
    adapter.addFragment(new Tab2Fragment(), "5 Sept 2018");
    adapter.addFragment(new Tab3Fragment(), "6 Sept 2018");
    viewPager.setAdapter(adapter);
}
 private void initialiseView() {

mTab1Fragment = new Tab1Fragment();

FragmentManager mFragmentManager = getSupportFragmentManager();

FragmentTransaction mFragmentTransaction = mFragmentManager.beginTransaction();

mFragmentTransaction.replace(R.id.container, mTab1Fragment, "TAB 1 FRAGMENT");

mFragmentTransaction.commit();

 }

@Override
public void onBackPressed() {

//Toast.makeText(this, "Calling back pressed", Toast.LENGTH_SHORT).show();

if (mTab1Fragment != null) {

    if (mTab1Fragment.webView.canGoBack()) {

        mTab1Fragment.webView.goBack();

    }

} else {

    super.onBackPressed();

}
}
}

Answer 1

This is your onCreateView method as per your need

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.tab1_fragment, container, false);

    webView = (WebView) view.findViewById(R.id.webview);

    WebSettings webSettings = webView.getSettings();
    webSettings.setJavaScriptEnabled(true);
    webView.setInitialScale(1);
    
    webView.getSettings().setLoadWithOverviewMode(true);
    webView.getSettings().setUseWideViewPort(true);
    
    webView.setScrollBarStyle(WebView.SCROLLBARS_OUTSIDE_OVERLAY);
    webView.setScrollbarFadingEnabled(false);
    webView.getSettings().setBuiltInZoomControls(true);
    webView.loadUrl("https://www.facebook.com/");
    webView.setWebViewClient(new WebViewClient());

    view.setFocusableInTouchMode(true);
    view.requestFocus();
    view.setOnKeyListener(new View.OnKeyListener() {
        @Override
        public boolean onKey(View view, int code, KeyEvent keyEvent) {

            if (code == KeyEvent.KEYCODE_BACK && keyEvent.getAction() == KeyEvent.ACTION_UP) {

                //Here is logic to handle back press event
                
                return true;

            }


            return false;
        }
    });

    return view;
}

Update to load previous page inside webview

Your onCreateView is same as you put in question. I made some simple change in Fragment.

Tab1 fragment will be like

public class Tab1Fragment extends Fragment {

Context mContext;

public WebView webView;

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.tab1_fragment, container, false);

    mContext = view.getContext();

    webView = (WebView) view.findViewById(R.id.webview);

    WebSettings webSettings = webView.getSettings();
    webSettings.setJavaScriptEnabled(true);
    webView.setInitialScale(1);
    webView.getSettings().setLoadWithOverviewMode(true);
    webView.getSettings().setUseWideViewPort(true);
    webView.setScrollBarStyle(WebView.SCROLLBARS_OUTSIDE_OVERLAY);
    webView.getSettings().setCacheMode(WebSettings.LOAD_CACHE_ELSE_NETWORK);
    webView.setScrollbarFadingEnabled(false);
    webView.getSettings().setBuiltInZoomControls(true);
    webView.loadUrl("https://www.facebook.com/");
    webView.setWebViewClient(new WebViewClient());

    return view;
}


}

Now your Activity will be

public class SampleActivity extends AppCompatActivity {

Tab1Fragment mTab1Fragment;

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


    initialiseView();

}

private void initialiseView() {

    mTab1Fragment = new Tab1Fragment();

    FragmentManager mFragmentManager = getSupportFragmentManager();

    FragmentTransaction mFragmentTransaction = mFragmentManager.beginTransaction();

    mFragmentTransaction.replace(R.id.container, mTab1Fragment, "TAB 1 FRAGMENT");

    mFragmentTransaction.commit();

}

@Override
public void onBackPressed() {

    //Toast.makeText(this, "Calling back pressed", Toast.LENGTH_SHORT).show();

    if (mTab1Fragment != null) {

        if (mTab1Fragment.webView.canGoBack()) {

            mTab1Fragment.webView.goBack();

        }

    } else {

        super.onBackPressed();
        
    }
}
}

NOTE: Here I kept webview public just for simplicity. Keep it private and use getter to access it. If you want to use more fragments then add TAG for each fragment and identify which fragment is visible.

Answer 2

The official solution from android

override fun onAttach(context: Context) {
    super.onAttach(context)
    val callback: OnBackPressedCallback = object : OnBackPressedCallback(
        true
    ) {
        override fun handleOnBackPressed() {
            // Leave empty do disable back press.
        }
    }
    requireActivity().onBackPressedDispatcher.addCallback(
        this,
        callback
    )
}

Alternate Solution 1

override fun onResume() {
    super.onResume()
    requireView().isFocusableInTouchMode = true
    requireView().requestFocus()
    requireView().setOnKeyListener { v, keyCode, event ->
        if (event.action === KeyEvent.ACTION_UP && keyCode == KeyEvent.KEYCODE_BACK) {
            // Add your code here
            true
        } else false
    }
}