Как onBackPressed() для андроидных фрагментов

Question

У меня есть 11 фрагментов, размещенных в MainActivity.class, эти фрагменты используют RecyclerView для отображения элементов. Элементы можно щелкнуть, когда они щелкнули элементы анализа данных в DetailActivity.class. MainActivity - это родительская активность. Я хочу реализовать onBackPressed(); таким образом, что, когда пользователь нажимает на кнопку homeBack в детали деятельности они будут возвращены к предыдущему фрагменту (прежнее положение в MianActivity)

MainActivity.class

public class MainActivity extends AppCompatActivity implements MaterialTabListener, View.OnClickListener, FragmentManager.OnBackStackChangedListener { 

    private static final int JOB_ID = 100; 
    private Toolbar toolbar; 
    private ViewPager mPager; 
    private MaterialTabHost mTabHost; 
    private SlidingTabLayout mTabs; 
    private ViewPagerAdapter adapter; 

    public static final int MOVIES_SEARCH_RESULTS = 1; 
    public static final int MOVIEE_HITS = 0; 
    public static final int MOVIES_UPCOMING = 2; 
    public static final int NEWS_OPINION = 3; 
    public static final int NEWS_CULTURE = 4; 
    public static final int NEWS_BUSINESS = 5; 
    public static final int NEWS_LIFESTYLE = 6; 
    public static final int NEWS_FASHION = 7; 
    public static final int NEWS_ENVIRONMENT = 8; 
    public static final int NEWS_TECH = 9; 
    public static final int NEWS_TRAVEL = 10; 


    public static final int TAB_COUNT = 11; 
    private JobScheduler mJobScheduler; 
    Realm mRealm; 
    FragmentManager mFragmentManager; 
    private static final String TAG_SORT_NAME = "sortName"; 
    private static final String TAG_SORT_DATE = "sortDate"; 
    private static final String TAG_SORT_RATINGS = "sortRatings"; 


    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     mJobScheduler = JobScheduler.getInstance(this); 
     mRealm = Realm.getDefaultInstance(); 
     toolbar = (Toolbar) findViewById(R.id.app_bar); 
     setSupportActionBar(toolbar); 
     getSupportActionBar().setDisplayHomeAsUpEnabled(true); 
     NavigationDrawerFragment drawerFragment = (NavigationDrawerFragment) 
       getSupportFragmentManager().findFragmentById(R.id.fragment_navigation_drawer); 
     drawerFragment.setUp(R.id.fragment_navigation_drawer, (DrawerLayout) findViewById(R.id.drawer_layout), toolbar); 
     mPager = (ViewPager) findViewById(R.id.pager); 
     mPager.setAdapter(new ViewPagerAdapter(getSupportFragmentManager())); 
     mTabs = (SlidingTabLayout) findViewById(R.id.tabs); 
     /*mTabHost = (MaterialTabHost) findViewById(R.id.materialTabHost);*/ 
     adapter = new ViewPagerAdapter(getSupportFragmentManager()); 
     mPager.setAdapter(adapter); 
     mTabs.setViewPager(mPager); 
     mFragmentManager=getSupportFragmentManager(); 
     mFragmentManager.addOnBackStackChangedListener(this); 
     Fragment fragment = new Business(); 
     // if you don't run on prior to Android 3.0 use getFragmentManager(); 
     mFragmentManager.beginTransaction().replace(R.id.businessFragment, fragment).addToBackStack(null).commit(); 
     // R.id.frame_container is the id of FrameLayout in activity_main.xml 





    } 

    @Override 
    public void onBackPressed() { 
     if(mFragmentManager.getBackStackEntryCount() == 0){ 
      finish(); 
     }else{ 
      super.onBackPressed(); 
     } 
    } 

    public void constructJob() { 
     JobInfo.Builder builder = new JobInfo.Builder(JOB_ID, new ComponentName(this, MyService.class)); 
    } 

    private void buildFAB() { 
     // in Activity Context 
     ImageView icon = new ImageView(this); // Create an icon 
     icon.setImageResource(R.drawable.ic_action_new); 
     FloatingActionButton actionButton = new FloatingActionButton.Builder(this) 
       .setContentView(icon) 
       .setBackgroundDrawable(R.drawable.selector_button_red) 
       .build(); 

// repeat many times: 
     ImageView iconSortName = new ImageView(this); 
     iconSortName.setImageResource(R.drawable.ic_action_alphabets); 
     ImageView iconSortDate = new ImageView(this); 
     iconSortDate.setImageResource(R.drawable.ic_action_calendar); 
     ImageView iconSortRatings = new ImageView(this); 
     iconSortRatings.setImageResource(R.drawable.ic_action_important); 

     // set background for all the buttons 
     SubActionButton.Builder itemBuilder = new SubActionButton.Builder(this); 
     itemBuilder.setBackgroundDrawable(getResources().getDrawable(R.drawable.selector_sub_button_gray)); 

     // build the sub buttons 
     SubActionButton buttonSortName = itemBuilder.setContentView(iconSortName).build(); 
     SubActionButton buttonSortDate = itemBuilder.setContentView(iconSortDate).build(); 
     SubActionButton buttonSortRatings = itemBuilder.setContentView(iconSortRatings).build(); 

     buttonSortName.setTag(TAG_SORT_NAME); 
     buttonSortDate.setTag(TAG_SORT_DATE); 
     buttonSortRatings.setTag(TAG_SORT_RATINGS); 

     buttonSortName.setOnClickListener(this); 
     buttonSortDate.setOnClickListener(this); 
     buttonSortRatings.setOnClickListener(this); 
     //Add the sub buttons to the main floating action button 
     FloatingActionMenu actionMenu = new FloatingActionMenu.Builder(this) 
       .addSubActionView(buttonSortName) 
       .addSubActionView(buttonSortDate) 
       .addSubActionView(buttonSortRatings) 

         // ... 
       .attachTo(actionButton) 
       .build(); 
    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     getMenuInflater().inflate(R.menu.menu_main, menu); 
     return true; 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     switch (item.getItemId()) { 

      case R.id.action_settings: 
       Toast.makeText(this, "Hey you just hit " + item.getTitle(), Toast.LENGTH_SHORT).show(); 
       return true; 
      case android.R.id.home: 
       getSupportFragmentManager().popBackStack(); 
       return true; 

     } 



     return onOptionsItemSelected(item); 
    } 

    @Override 
    public void onTabSelected(MaterialTab tab) { 
     mPager.setCurrentItem(tab.getPosition()); 

    } 

    @Override 
    public void onTabReselected(MaterialTab tab) { 

    } 

    @Override 
    public void onTabUnselected(MaterialTab tab) { 

    } 

    @Override 
    public void onClick(View v) { 
     //call instantiate item since getItem may return null depending on whether the PagerAdapter is of type FragmentPagerAdapter or FragmentStatePagerAdapter 
     Fragment fragment = (Fragment) adapter.instantiateItem(mPager, mPager.getCurrentItem()); 
     if (fragment instanceof SortListener) { 

      if (v.getTag().equals(TAG_SORT_NAME)) { 
       //call the sort by name method on any Fragment that implements sortlistener 
       ((SortListener) fragment).onSortByName(); 
      } 
      if (v.getTag().equals(TAG_SORT_DATE)) { 
       //call the sort by date method on any Fragment that implements sortlistener 
       ((SortListener) fragment).onSortByDate(); 
      } 
      if (v.getTag().equals(TAG_SORT_RATINGS)) { 
       //call the sort by ratings method on any Fragment that implements sortlistener 
       ((SortListener) fragment).onSortByRatings(); 
      } 
     } 
    } 

    @Override 
    public void onBackStackChanged() { 
    /* if (getSupportFragmentManager().getBackStackEntryCount()==1){ 
      finish(); 
     }else { 
      super.onBackPressed(); 
     }*/ 

    } 


    /* private void replaceFragment(Fragment fragment) { 
     String backStackName = fragment.getClass().getName(); 
     boolean fragmentPopped = mFragmentManager.popBackStackImmediate(backStackName, 0); 
     if (!fragmentPopped) { 
      fragmentTransaction.replace(R.id.container, fragment); 
      fragmentTransaction.addToBackStack(backStackName); 
      fragmentTransaction.commit(); 
     } 
    }*/ 

    class ViewPagerAdapter extends FragmentStatePagerAdapter { 
     /*private String tabs[] = new String[]{"Tab 1 ", "Tab 2 ", " Tab 3"};*/ 
    /* int icons[] = {R.drawable.ic_home_black_24dp, 
       R.drawable.ic_library_books_black_24dp, 
       R.drawable.ic_person_black_24dp, 

     };*/ 

     String[] tabText; 
     FragmentManager fragmentManager; 

     public ViewPagerAdapter(FragmentManager fm) { 
      super(fm); 
      tabText = getResources().getStringArray(R.array.tabs); 
      fragmentManager = fm; 

     } 

     @Override 
     public Fragment getItem(int num) { 
      Fragment fragment = null; 
      switch (num) { 
       case MOVIES_SEARCH_RESULTS: 
        fragment = FragmentSearch.newInstance("", ""); 
        break; 
       case MOVIEE_HITS: 
        fragment = FragmentBoxOffice.newInstance("", ""); 

        break; 
       case MOVIES_UPCOMING: 
        fragment = FragmentUpcoming.newInstance("", ""); 

        break; 
       case NEWS_OPINION: 
        fragment = Opinion.newInstance("", ""); 
        break; 
       case NEWS_CULTURE: 
        fragment = Culture.newInstance("", ""); 
        break; 
       case NEWS_BUSINESS: 
        fragment = Business.newInstance("", ""); 
        break; 
       case NEWS_LIFESTYLE: 
        fragment = Lifestyle.newInstance("", ""); 
        break; 
       case NEWS_FASHION: 
        fragment = Fashion.newInstance("", ""); 
        break; 
       case NEWS_ENVIRONMENT: 
        fragment = Environment.newInstance("", ""); 
        break; 
       case NEWS_TECH: 
        fragment = Tech.newInstance("", ""); 
        break; 
       case NEWS_TRAVEL: 
        fragment = Travel.newInstance("", ""); 
        break; 
      } 
      return fragment; 
     } 


     @Override 
     public int getCount() { 
      return TAB_COUNT; 
     } 

     @Override 

     public CharSequence getPageTitle(int position) { 
      return tabText[position]; 
     } 

     /* private Drawable getIcon(int position) { 
      return getResources().getDrawable(icons[position]); 
     }*/ 
    } 

} 

DetailActivity.class

public class DetailActivity extends AppCompatActivity { 
    private Toolbar mToolbar; 
    private ViewPager mPager; 
    private ViewGroup mCointainerTooobar; 
    private VolleySingleton volleySingleton; 
    private ImageLoader imageLoader; 

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

     mToolbar = (Toolbar) findViewById(R.id.toolbarf); 
     setSupportActionBar(mToolbar); 
     final CollapsingToolbarLayout collapsingToolbarLayout = 
       (CollapsingToolbarLayout) findViewById(R.id.collapsing_toolbar_layout); 
     Bundle extra = getIntent().getExtras(); 
     String detailsSectionId = extra.getString("SectionId"); 
     collapsingToolbarLayout.setTitle(detailsSectionId.toString().trim()); 
     ImageView flexibleHeader = (ImageView) findViewById(R.id.ivProfileImage); 
     mCointainerTooobar = (ViewGroup) findViewById(R.id.container_app_bar); 
     volleySingleton = VolleySingleton.getsInstance(); 
     imageLoader = volleySingleton.getImageLoader(); 
     getSupportActionBar().setDisplayHomeAsUpEnabled(true); 
     getSupportActionBar().setHomeButtonEnabled(true); 
     displayingDetails(); 
    /*  Bitmap mBitmap= BitmapFactory.decodeResource(getResources(), R.id.ivProfileImage); 
     Palette.from(mBitmap).generate(new Palette.PaletteAsyncListener() { 

      @Override 


      public void onGenerated(Palette palette) { 
       String mutecolor; 

       collapsingToolbarLayout.setContentScrim(Palette.g); 
      } 
     });*/ 


    } 

    @Override 
    public void onBackPressed() { 
     if (getFragmentManager().getBackStackEntryCount() > 0) { 
      getFragmentManager().popBackStack(); 
     } else { 
      super.onBackPressed(); 
     } 
    } 

    public void displayingDetails() { 
     // seactionId 
     Bundle extra = getIntent().getExtras(); 
     String detailsSectionId = extra.getString("SectionId"); 
     TextView sectionText = (TextView) findViewById(R.id.DetailsSectionId); 
     sectionText.setText(detailsSectionId); 
     // Title 
     Bundle titleText = getIntent().getExtras(); 
     String title = titleText.getString("title"); 
     TextView titleView = (TextView) findViewById(R.id.DetailNews_title); 
     titleView.setText(title); 
     // Thumbnail 
     Bundle mUrlThumbnail = getIntent().getExtras(); 
     String urlThumbnail = mUrlThumbnail.getString("UrlThumbnail"); 
     final ImageView urlThumbnailView = (ImageView) findViewById(R.id.ivProfileImage); 
     if (urlThumbnail != null) { 
      imageLoader.get(urlThumbnail, new ImageLoader.ImageListener() { 
       @Override 
       public void onErrorResponse(VolleyError error) { 

       } 

       @Override 
       public void onResponse(ImageLoader.ImageContainer response, boolean isImmediate) { 
        urlThumbnailView.setImageBitmap(response.getBitmap()); 
       } 
      }); 
      urlThumbnailView.setBackgroundDrawable(Drawable.createFromPath(urlThumbnail)); 
     } 
     // Body 
     Bundle mBody = getIntent().getExtras(); 
     /*String body= Html.fromHtml(mBody.getString("body"));*/ 
     String body = mBody.getString("body"); 
     TextView bodyView = (TextView) findViewById(R.id.DetailsNews_description); 
     bodyView.setText(Html.fromHtml(body)); 
     bodyView.setMaxLines(1000000); 


    } 

    /* @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     switch (item.getItemId()){ 
      case android.R.id.home: 
       L.t(DetailActivity.this, "this is the details activity"); 
       getFragmentManager().popBackStack(); 

       return true; 
     } 
     return super.onOptionsItemSelected(item); 
    }*/ 
} 

Как реализовать эту функциональность, Любое решение будет высоко оценено.

Answer 1

Когда вы вернетесь из своей активной деятельности, вы хотите вернуться MainActivity в том месте, где вы были в последний раз. Вы можете сохранить маркер вашего текущего фрагмента, а в своей функции OnResume вы можете заменить фрагмент фрагментом, который был ранее.

Если вы хотите реализовать кнопку «Назад», нажмите внутри фрагмента. Вот подходящий код для этого. Это очень актуально с вопросом, который вы задали. Но я поставил его здесь для заголовка вопроса.

Внутри вашего onCreateView установлено KeyListener вот так.

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
    View v = inflater.inflate(R.layout.your_fragment_layout, container, false); 

    // Handle back press action when action mode is on. 
    v.setFocusableInTouchMode(true); 
    v.requestFocus(); 
    v.setOnKeyListener(new View.OnKeyListener() { 
     @Override 
     public boolean onKey(View v, int keyCode, KeyEvent event) { 
      if (keyCode == KeyEvent.KEYCODE_BACK) { 

       if (haveToDoSomething) { 
        // Do something 
       } 
       else return false; 
      } 

      return true; 
     } 
    }); 
}