片段OnBackPressed？

Question

I have a doubt i have one activity inside that there are three fragments namely a,b,c transaction will be like a->b->. my doubt is when i enter back button from b it must go to fragment a and frag b should return to its default state how can i achieve it ? am really confused as am new to android i hope you guys are here to help

Here is my Fragment A code:

  import android.app.Fragment;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.ListView;

import java.util.ArrayList;

public class Leads extends Fragment implements View.OnClickListener {

    public Leads(){}

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

        View rootView = inflater.inflate(R.layout.fragment_one, container, false);

        ArrayList<NewsItem> listContact = GetlistContact();
        ListView lv = (ListView) rootView.findViewById(R.id.listView);
        lv.setAdapter(new CustomListAdapter(getActivity(), listContact));


        return rootView;

    }

    private ArrayList<NewsItem> GetlistContact(){
        ArrayList<NewsItem> contactlist = new ArrayList<NewsItem>();

        NewsItem contact = new NewsItem();
        for(int i=1;i<=30;i++) {
            contact = new NewsItem();
            contact.setHeadline("Yoge " +i);
            contact.setReporterName("Yogeshwaran" + i);
            contact.setLeadsource("Yogan" + i);
            contact.setLeadStatus("open" + i);
            contact.setLeadType("Business"+i);
            contactlist.add(contact);

        }

        return contactlist;
    }
    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        Fragment fragment=null;
        Button add = (Button) getActivity().findViewById(R.id.btnadd);
        add.setOnClickListener(this);
        ImageButton   filter = (ImageButton) getActivity().findViewById(R.id.btnfilter);
        filter.setOnClickListener(this);

    }
    String str="";
    @Override

    public void onClick(View v) {
        switch (v.getId()){
            case R.id.btnadd:
                Fragment newFragment = new Add();
                str="add";
                // consider using Java coding conventions (upper first char class names!!!)
                FragmentTransaction transaction = getFragmentManager().beginTransaction();

                // Replace whatever is in the fragment_container view with this fragment,
                // and add the transaction to the back stack
                transaction.replace(R.id.content_frame, newFragment,str);
                transaction.addToBackStack(null);

                // Commit the transaction
                transaction.commit();

        }
    }



}

Here is my frag b code:

    package first.service.precision.servicefirst;

/**
 * Created by 4264 on 23-11-2015.
 */
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Spinner;
import android.widget.TextView;

import java.util.ArrayList;

/**
 * Created by 4264 on 16-10-2015.
 */
public  class Add extends Fragment implements View.OnClickListener {
    public static ListView lv;
    static String sbu, sbuu, sc, ssc, req;
    static String bu;
    customListAdapterldrequirements customListAdapterldrequirements;

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        try {
            View rootView = inflater.inflate(R.layout.activity_btn_add, container, false);
            Spinner ldsource = (Spinner) rootView.findViewById(R.id.lead_source);
            ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(
                    getActivity().getBaseContext(), R.array.dropbox1, R.layout.spinnerlayout);


            adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
            ldsource.setAdapter(adapter);
            //   EditText editText=(EditText)rootView.findViewById(R.id.title);

            Spinner ldtype = (Spinner) rootView.findViewById(R.id.ldtype);
            ArrayAdapter<CharSequence> adapter1 = ArrayAdapter.createFromResource(
                    getActivity().getBaseContext(), R.array.dropbox2, R.layout.spinnerlayout);

            adapter1.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
            ldtype.setAdapter(adapter1);
            Spinner ldstatus = (Spinner) rootView.findViewById(R.id.ldstatus);
            TextView txt = (TextView) rootView.findViewById(R.id.spinnerTarget);
            ArrayAdapter<CharSequence> adapter2 = ArrayAdapter.createFromResource(
                    getActivity().getBaseContext(), R.array.dropbox3, R.layout.spinnerlayout);

            adapter2.setDropDownViewResource(android.R.layout.simple_selectable_list_item);
            ldstatus.setAdapter(adapter2);
            //  Bundle bundle=getArguments();
            //  String good=bundle.getString("sbu");


            Bundle bundle = getArguments();

//            sbu = getArguments().getString("yes");
            ArrayList<LdNewsItem> listContact = GetlistContact();

            //    public boolean onTouch(View v, MotionEvent event) {
            //        return false;
            // }

            // Setting on Touch Listener for handling the touch inside ScrollView


            //});
            lv = (ListView) rootView.findViewById(R.id.ldrequirements);
            customListAdapterldrequirements = new customListAdapterldrequirements(getActivity(), listContact);
            lv.setAdapter(customListAdapterldrequirements);
            // customListAdapterldrequirements customListAdapterldrequirements=new customListAdapterldrequirements(getActivity(),listContact);

            lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> parent, View view, int position,
                                        long id) {
                    NewRequirements newRequirements = new NewRequirements();
                    FragmentManager fm = getFragmentManager();
                    FragmentTransaction ft = fm.beginTransaction();
                    ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);

                    //  lv.deferNotifyDataSetChanged();
                    ft.replace(R.id.content_frame, newRequirements, "hi");
                    ft.addToBackStack(null);
                    ft.commit();

                }
            });
      /*  lv.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                return false;
            }


            // Setting on Touch Listener for handling the touch inside ScrollView
      //      @Override
        //    public boolean onTouch(View v, MotionEvent event) {
                // Disallow the touch request for parent scroll on touch of child view

          //      v.getParent().requestDisallowInterceptTouchEvent(true);
//
  //              return false;
    //        }
        });*/
            return rootView;

        } catch (Exception e) {
            throw e;
        }
    }

    public void updateListView() {
        customListAdapterldrequirements.notifyDataSetChanged();
    }

    private ArrayList<LdNewsItem> GetlistContact() {
        ArrayList<LdNewsItem> contactlist = new ArrayList<LdNewsItem>();
        //    String str=getArguments().getString("yes");

        sbu = Main2Activity.sbu;
        bu = Main2Activity.bu;
        sbuu = Main2Activity.sbuu;
        sc = Main2Activity.sc;
        ssc = Main2Activity.ssc;
        req = Main2Activity.req;
        for (int i = 1; i <= 5; i++) {
            LdNewsItem contact = new LdNewsItem();
            contact.setSbu(sbu);
            contact.setBu(bu);
            contact.setSbuu(sbuu);
            contact.setSc(sc);
            contact.setSsc(ssc);
            contact.setReq(req);
            // contact.setReporterName("No matter how big your house is, how recent your car is, or how big your bank account is — our graves will always be the same size. Stay humble." + i);
            contactlist.add(contact);
//lv.setAdapter((ListAdapter) contactlist);

        }

        return contactlist;
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        Fragment fragment = null;
        setHasOptionsMenu(true);
        Button btnrequirements = (Button) getActivity().findViewById(R.id.btnrequirements);
        btnrequirements.setOnClickListener(this);
        Button btnactnt = (Button) getActivity().findViewById(R.id.btnacnt);
        btnactnt.setOnClickListener(this);
        Button btnprimary = (Button) getActivity().findViewById(R.id.btnprimary);
        btnprimary.setOnClickListener(this);
        Button btnsecondary = (Button) getActivity().findViewById(R.id.btnsecondary);
        btnsecondary.setOnClickListener(this);

    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.btnrequirements:
                Fragment newFragment = new NewRequirements();
                // consider using Java coding conventions (upper first char class names!!!)
                FragmentTransaction transaction = getFragmentManager().beginTransaction();
                // Replace whatever is in the fragment_container view with this fragment,
                // and add the transaction to the back stack
                transaction.replace(R.id.content_frame, newFragment);
                transaction.addToBackStack(null);
                // Commit the transaction
                transaction.commit();
                break;

            case R.id.btnacnt:
                FragmentManager fm = getFragmentManager();
                //FragmentTransaction ft=fm.beginTransaction();
                SelectAccountDialog selectAccountDialog = new SelectAccountDialog();
                selectAccountDialog.setRetainInstance(true);
                selectAccountDialog.show(fm, "fragment_name");
                //ft.addToBackStack(null);

                break;
            case R.id.btnprimary:
                FragmentManager fmm = getFragmentManager();
                // FragmentTransaction ftt=fmm.beginTransaction();
                SelectAccountDialog selectAccountDialog1 = new SelectAccountDialog();
                selectAccountDialog1.setRetainInstance(true);
                selectAccountDialog1.show(fmm, "fragment_name");
                //   ftt.addToBackStack(null);
                break;
            case R.id.btnsecondary:
                FragmentManager fm2 = getFragmentManager();
                //     FragmentTransaction fttt=fm2.beginTransaction();
                SelectAccountDialog selectAccountDialog2 = new SelectAccountDialog();
                selectAccountDialog2.setRetainInstance(true);
                selectAccountDialog2.show(fm2, "fragment_name");
                //     fttt.addToBackStack(null);
                break;

        }

    }


    /*@Override
    public void onDestroyView() {
        // TODO Auto-generated method stub
        super.onDestroyView();
        Leads leads=new Leads();
FragmentManager back=getFragmentManager();
        FragmentTransaction ft=back.beginTransaction();
        ft.replace(R.id.content_frame,leads);
        ft.addToBackStack(null);
        ft.commit();


    }*/
}

My activity as below:

package first.service.precision.servicefirst;

import android.annotation.SuppressLint;
import android.app.ActionBar;
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.os.Bundle;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.util.Log;
import android.view.Gravity;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;


public class Main2Activity extends Activity  {

    public static String sbu,bu,sbuu,sc,ssc,req;

    // Within which the entire activity is enclosed
    private DrawerLayout mDrawerLayout;

    // ListView represents Navigation Drawer
    private ListView mDrawerList;
    Button butonlead;
    // ActionBarDrawerToggle indicates the presence of Navigation Drawer in the action bar
    private ActionBarDrawerToggle mDrawerToggle;

    // Title of the action bar
    private String mTitle = "";


    @SuppressLint("NewApi")
    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);

        final ActionBar ab = getActionBar();
        ab.show();
        // Getting reference to the DrawerLayout
        mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
        ab.setTitle(mTitle);

        mDrawerList = (ListView) findViewById(R.id.drawer_list);

        // Getting reference to the ActionBarDrawerToggle
        mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,

                R.string.open_drawer,
                R.string.close_drawer) {

            /** Called when drawer is closed */
            public void onDrawerClosed(View view) {

                invalidateOptionsMenu();

            }

            /** Called when a drawer is opened */
            public void onDrawerOpened(View drawerView) {

                invalidateOptionsMenu();
            }


        };

        // Setting DrawerToggle on DrawerLayout
        mDrawerLayout.setDrawerListener(mDrawerToggle);

        // Creating an ArrayAdapter to add items to the listview mDrawerList
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(getApplication(),
                R.layout.drawer_list_item, R.id.title, getResources().getStringArray(R.array.option));

        // Setting the adapter on mDrawerList
        mDrawerList.setAdapter(adapter);

        // Enabling Home button
        ab.setHomeButtonEnabled(true);
        ab.setBackgroundDrawable(new ColorDrawable(Color.parseColor("#53A93F")));
        // Enabling Up navigation
        ab.show();
        ab.setDisplayHomeAsUpEnabled(true);

        // Setting item click listener for the listview mDrawerList
        mDrawerList.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                                    int position, long id) {

                // Getting an array of options
                String[] menuItems = getResources().getStringArray(R.array.option);

                // Currently selected option
                mTitle = menuItems[position];

                Fragment fragment = null;
                String tag="";
                switch (position) {
                    case 0:
                        fragment = new Leads();
                        tag="leads";
                        break;
                    case 1:
                        fragment = new Opportunities();
                        break;
                    case 2:
                        fragment = new Accounts();
                        break;
                    case 3:
                        fragment = new Contactss();
                        break;
                    case 4:
                        fragment = new Documents();
                        break;
                    case 5:
                        fragment = new Reports();
                    default:
                        break;
                }
                if (fragment != null) {
                    // Getting reference to the FragmentManager
                    FragmentManager fragmentManager = getFragmentManager();
                    fragmentManager.beginTransaction().replace(R.id.content_frame, fragment,tag).addToBackStack("fragback").commit();
                    // Creating a fragment transaction
                    FragmentTransaction ft = fragmentManager.beginTransaction();

                    // Adding a fragment to the fragment transaction
                    ft.replace(R.id.content_frame, fragment);

                    // Committing the transaction
                    ft.commit();

                    // Closing the drawer
                    mDrawerLayout.closeDrawer(mDrawerList);
                } else {
                    // error in creating fragment
                    Log.e("MainActivity", "Error in creating fragment");
                }

            }
        });
    }

    @Override
    public void onBackPressed() {
        if (mDrawerLayout.isDrawerOpen(Gravity.LEFT)) {
            mDrawerLayout.closeDrawer(mDrawerList);
        } else {
            FragmentManager manager = getFragmentManager();

            manager.popBackStack();
            super.onBackPressed();
        }

    }
    public void changeFragment(Fragment fragment, String tag, boolean shouldAddToBackStack) {

        try {
            FragmentTransaction ft = getFragmentManager().beginTransaction();
            if (shouldAddToBackStack)
                ft.addToBackStack(tag);
            else {
                getFragmentManager().popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
            }
            ft.replace(R.id.content_frame, fragment, tag)
                    .commit();
            getFragmentManager().executePendingTransactions();
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    @Override
    protected void onPostCreate(Bundle savedInstanceState) {
        super.onPostCreate(savedInstanceState);
        mDrawerToggle.syncState();
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (mDrawerToggle.onOptionsItemSelected(item)) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    /**
     * Called whenever we call invalidateOptionsMenu()
     */
    @Override
    public boolean onPrepareOptionsMenu(Menu menu) {
        // If the drawer is open, hide action items related to the content view
        boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList);


        return super.onPrepareOptionsMenu(menu);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.main2, menu);
        return super.onCreateOptionsMenu(menu);
    }



   /* @Override
    public void DataTransfer(String e) {


    }*/
//
    // @Override
    //  public void DataTransfer(ArrayList<String> e) {
    //     Add obj=(Add)getFragmentManager().findFragmentById(R.id.frag_1);
    //   obj.GetlistContact(e);
    // }
}
  /*  @Override
    public void selectedvalue(String s) {
            Add add=new Add();
            FragmentManager fm=getFragmentManager();
            FragmentTransaction ft=fm.beginTransaction();
            ft.replace(R.id.content_frame,add);
            ft.commit();}
    }
*/

Answer 1

There is only one backstack for your application.it is a stack and if we added our fragment to this stack, while pressing back button it will pop out. in your case you can add below code to switch your fragments .put this code both in your main activity as well as parent fragments. pass shouldAddToBackStack as true which fragments you want to add in backstack and it will automatically pop out once you press backbutton

you should replace all this

Fragment newFragment = new NewRequirements();
                // consider using Java coding conventions (upper first char class names!!!)
                FragmentTransaction transaction = getFragmentManager().beginTransaction();
                // Replace whatever is in the fragment_container view with this fragment,
                // and add the transaction to the back stack
                transaction.replace(R.id.content_frame, newFragment);
                transaction.addToBackStack(null);
                // Commit the transaction
                transaction.commit();

with this function

   public void changeFragment(Fragment fragment, String tag, boolean shouldAddToBackStack) {

            try {
                FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
                if (shouldAddToBackStack)
                    ft.addToBackStack(tag);
                else {
                    getActivity().getSupportFragmentManager().popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
                }
                ft.replace(R.id.container, fragment, tag)
                        .commit();
                getActivity().getSupportFragmentManager().executePendingTransactions();
            } catch (Exception ex) {
                ex.printStackTrace();
            }
       }

Answer 2

When you're adding the second fragment to the activity, add the first fragment to back stack:

fragmentTransaction.addToBackStack("fragmentATag");

also override the activity's onBackPressed() method:

@Override
public void onBackPressed() {
     FragmentManager manager = getSupportFragmentManager();
     if (manager.getBackStackEntryCount() > 0) 
         manager.popBackStack();

}

Answer 3

write getActivity().getFragmentManager().popBackStack(); in onBackPressedMethod()

Answer 4

You can do this way:

Replace Fragment by below code:

android.support.v4.app.FragmentManager fragmentManager = getSupportFragmentManager();
android.support.v4.app.FragmentTransaction ft = fragmentManager.beginTransaction();    
ft.replace(R.id.content_view, new FragmentB());
ft.addToBackStack(null);
ft.commit();   

No need to do code in Fragment B to come back to Fragment A , it will automatically handle, when you press hard back key , if you want to add custom button for coming back from Fragment B to Fragment A than you have to add getActivity.onBackPressed() .

Hope this will help you.