处理返回按钮去HomeFragment？

Question

抽屉式导航处理后退按钮去HomeFragment

这是SecurityFragment

 import android.app.FragmentTransaction; 
     import android.os.Bundle; 
     import android.app.Fragment; 
     import android.view.LayoutInflater; 
     import android.view.View; 
     import android.view.ViewGroup; 


     /** 
     * A simple {@link Fragment} subclass. 
     */ 
     public class SecurityFragment extends Fragment { 


      public SecurityFragment() { 
       // Required empty public constructor 
      } 



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

       // Inflate the layout for this fragment 
       return inflater.inflate(R.layout.fragment_security, container, false); 
      } 


     } 

这是HomeFragment（当onBackPressed我只是希望用户被引导到主页）目前的情况是，上onBackPressed运行的应用程序被破坏

 package sampleapp.razen.com.sampleapp; 

    import android.content.Intent; 
    import android.os.Bundle; 
    import android.support.design.widget.FloatingActionButton; 
    import android.support.design.widget.NavigationView; 
    import android.support.design.widget.Snackbar; 
    import android.support.v4.view.GravityCompat; 
    import android.support.v4.widget.DrawerLayout; 
    import android.support.v7.app.ActionBarDrawerToggle; 
    import android.support.v7.app.AppCompatActivity; 
    import android.support.v7.widget.Toolbar; 
    import android.view.MenuItem; 
    import android.view.View; 
    import android.app.Fragment; 
    import android.app.FragmentTransaction; 
    import android.widget.Toast; 

    public class Menu extends AppCompatActivity 
      implements NavigationView.OnNavigationItemSelectedListener { 


     @Override 
     protected void onCreate(Bundle savedInstanceState) { 
      super.onCreate(savedInstanceState); 
      setContentView(R.layout.activity_menu); 
      android.app.Fragment fragment = new MenuFragment(); // create a fragement object 
      FragmentTransaction ft = getFragmentManager().beginTransaction(); 
      ft.replace(R.id.mainFrame, fragment); 
      ft.commit(); 


      Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
      setSupportActionBar(toolbar); 

      FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab); 
      fab.setOnClickListener(new View.OnClickListener() { 

    //this the email icon on the home page 
       @Override 
       public void onClick(View view) { 
        String myEmail[]={"john@balloonventures.com"}; 
        Intent sendMail = new Intent(Intent.ACTION_SEND); 
        sendMail.putExtra(Intent.EXTRA_EMAIL,myEmail); 
        sendMail.putExtra(Intent.EXTRA_SUBJECT,"(Type your subject)"); 
        sendMail.setType("plain/text"); 
        //incase you have to add something else put here 
        sendMail.putExtra(Intent.EXTRA_TEXT,"Your phone:+2547"); 
        startActivity(sendMail); 


       } 

      }); 

      DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout); 
      ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
        this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close); 
      drawer.setDrawerListener(toggle); 
      toggle.syncState(); 

      NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view); 
      navigationView.setNavigationItemSelectedListener(this); 
     } 
    //taxi module 
     public void taxi_id(View view){ 
      Intent timer=new Intent(this,sampleapp.razen.com.sampleapp.Taxi.class); 
      startActivity(timer);} 
    //host home module 
     public void hosthome_id(View view){ 
      Intent timer=new Intent(this,sampleapp.razen.com.sampleapp.MainActivity.class); 
      startActivity(timer);} 
     //calling enterprenuers module 
     public void enter_id(View view){ 
      Intent timer=new Intent(this,sampleapp.razen.com.sampleapp.SectionListView.class); 
      startActivity(timer);} 
     //calling UKV/ICV 
     public void ukvicv_id(View view){ 
      Intent timer=new Intent(this,sampleapp.razen.com.sampleapp.UkvIcv_Home.class); 
      startActivity(timer);} 
     public void finacial_id(View view){ 
      Intent finacial=new Intent(this,sampleapp.razen.com.sampleapp.FinacialHomePage.class); 
      startActivity(finacial);} 


     @Override 
     public void onBackPressed() { 
      DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout); 
      if (drawer.isDrawerOpen(GravityCompat.START)) { 
       drawer.closeDrawer(GravityCompat.START); 
      } else { 
       super.onBackPressed(); 
      } 
     } 



     @Override 
     public boolean onOptionsItemSelected(MenuItem item) { 
      // Handle action bar item clicks here. The action bar will 
      // automatically handle clicks on the Home/Up button, so long 
      // as you specify a parent activity in AndroidManifest.xml. 
      int id = item.getItemId(); 

      //noinspection SimplifiableIfStatement 
      if (id == R.id.action_settings) { 
       return true; 
      } 

      return super.onOptionsItemSelected(item); 
     } 

     public void displayView(int viewId) { 

      Fragment fragment = null; 
      String title = getString(R.string.app_name); 

      switch (viewId) { 
       case R.id.nav_12wks_program: 
        Intent timer=new Intent(this,sampleapp.razen.com.sampleapp.ExpandableListMainActivity.class); 
        startActivity(timer); 

        break; 


       case R.id.nav_emergency_contact: 
        Intent flow=new Intent(this,sampleapp.razen.com.sampleapp.EmergencyContact.class); 
        startActivity(flow); 

        break; 


       case R.id.nav_survey: 
        fragment = new SurveyFragment(); 
        title = "Survey"; 
        break; 

       case R.id.nav_psld: 
        fragment = new PsldFragment(); 
        title = "Psld"; 

        break; 
       case R.id.nav_security: 
        fragment = new SecurityFragment(); 
        title = "All Volunteers Mu"; 

        break; 
       case R.id.nav_ukv: 
        fragment = new UkvKiswaFragment(); 
        title = "Ukv's kiswahili"; 

        break; 

       case R.id.nav_agreement: 
        fragment = new AgreementFragment(); 
        title = "Agreement "; 

        break; 
       case R.id.nav_njoro_geo: 
        fragment = new GeoNjoroFragment(); 
        title = "Njoro Geography "; 

        break; 




      } 

      if (fragment != null) { 
       FragmentTransaction ft = getFragmentManager().beginTransaction(); 
       ft.replace(R.id.mainFrame, fragment); 
       ft.commit(); 
      } 

      // set the toolbar title 
      if (getSupportActionBar() != null) { 
       getSupportActionBar().setTitle(title); 
      } 

      DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout); 
      drawer.closeDrawer(GravityCompat.START); 

     } @SuppressWarnings("StatementWithEmptyBody") 

     @Override 
     public boolean onNavigationItemSelected(MenuItem item) { 
      displayView(item.getItemId()); 
      return true; 
     } 
    } 

Answer 1

您的片段横断添加到碎片堆栈中befor提交

FragmentTransaction ft = getFragmentManager().beginTransaction(); 
     ft.replace(R.id.mainFrame, fragment); 
     ft.addToBackStack("tag"); 
     ft.commit();