一次又一次停止重建片段

Question

在我的应用程序中，我通过这些代码行提供导航抽屉

 switch (menuItem.getItemId()) {
                        case R.id.home:
                            menuItem.setChecked(true);
                            drawerLayout.closeDrawer(GravityCompat.START);
                                fragment = new HomeFragment();
                                fragmentManager.beginTransaction().replace(R.id.list_view_container, fragment).commit();
                            return true;
                        case R.id.current_event:
                            menuItem.setChecked(true);
                            drawerLayout.closeDrawer(GravityCompat.START);
                            return true;
                        case R.id.college_events:
                            menuItem.setChecked(true);
                            drawerLayout.closeDrawer(GravityCompat.START);
                            return true;
                        case R.id.national_events:
                            menuItem.setChecked(true);
                            drawerLayout.closeDrawer(GravityCompat.START);
                            return true;
                        case R.id.workshops:
                            menuItem.setChecked(true);
                            drawerLayout.closeDrawer(GravityCompat.START);
                            return true;
                        case R.id.trainings:
                            menuItem.setChecked(true);
                            Toast.makeText(MainActivity.this, "Launching " + menuItem.getTitle().toString(), Toast.LENGTH_SHORT).show();
                            drawerLayout.closeDrawer(GravityCompat.START);
                            return true;
                        case R.id.companies:
                            menuItem.setChecked(true);
                            Toast.makeText(MainActivity.this, menuItem.getTitle().toString(), Toast.LENGTH_SHORT).show();
                            drawerLayout.closeDrawer(GravityCompat.START);
                            return true;
                        case R.id.talents:
                            menuItem.setChecked(true);
                            Toast.makeText(MainActivity.this, menuItem.getTitle().toString(), Toast.LENGTH_SHORT).show();
                            drawerLayout.closeDrawer(GravityCompat.START);
                            return true;
                        case R.id.games:
                            menuItem.setChecked(true);
                            Toast.makeText(MainActivity.this, menuItem.getTitle().toString(), Toast.LENGTH_SHORT).show();
                            drawerLayout.closeDrawer(GravityCompat.START);
                            return true;
                        case R.id.submission:
                                menuItem.setChecked(true);
                                Toast.makeText(MainActivity.this, menuItem.getTitle().toString(), Toast.LENGTH_SHORT).show();
                                drawerLayout.closeDrawer(GravityCompat.START);
                                return true;
                        case R.id.about:
                                menuItem.setChecked(true);
                                Toast.makeText(MainActivity.this, menuItem.getTitle().toString(), Toast.LENGTH_SHORT).show();
                                drawerLayout.closeDrawer(GravityCompat.START);
                                return true;
                }

每次新选择进行时，片段会一次又一次地重建我只想暂停每个片段的最后状态并唤醒他们的选择而不重建。

Answer 1

你应该使用这样的东西：

               case 1:
                    if(getSupportFragmentManager().findFragmentByTag("ranking")==null) {
                        getSupportFragmentManager().beginTransaction().add(R.id.fragment_holder,
                                new RankingFragment(), "ranking").
                                addToBackStack("ranking").
                                setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN)
                                .commit();

                    } else {
                        getSupportFragmentManager().popBackStack("ranking", 0);
                    }
                    break;