getSupportFragmentManager().findFragmentByTag() 返回 null？答案

【问题标题】：getSupportFragmentManager().findFragmentByTag() returns null?getSupportFragmentManager().findFragmentByTag() 返回 null？
【发布时间】：2018-07-14 08:42:16
【问题描述】：

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_home_screen_bottombar);
        BottomNavigationView bottomNavigationView = findViewById(R.id.navigation);
        BottomNavigationViewHelper.disableShiftMode(bottomNavigationView);
        initBottomBar(bottomNavigationView);}
    private void initBottomBar(BottomNavigationView bottomNavigationView) {
        bottomNavigationView.setOnNavigationItemSelectedListener
                (new BottomNavigationView.OnNavigationItemSelectedListener() {
                    @Override
                    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                        switch (item.getItemId()) {
                            case R.id.home:
                                fragmentTag = "home";
                                savedFragment = getSupportFragmentManager().findFragmentByTag(fragmentTag);
                                if (savedFragment == null)
                                    savedFragment = NeedyFeedyHomeTabFragment.getInstance();
                                break;
                            case R.id.search:
                                fragmentTag = "search";
                                savedFragment = getSupportFragmentManager().findFragmentByTag(fragmentTag);
                                if (savedFragment == null) {
                                    savedFragment = SearchResultFragment.getInstance();
                                }
                                break;
                            case R.id.profile:
                                fragmentTag = "profile";
                                savedFragment = getSupportFragmentManager().findFragmentByTag(fragmentTag);
                                if (savedFragment == null) {
                                    savedFragment = FragmentProfileDetails.getInstance();
                                }
                                break;
                            case R.id.favourite:
                                fragmentTag = "favourite";
                                savedFragment = getSupportFragmentManager().findFragmentByTag(fragmentTag);
                                if (savedFragment == null) {
                                    savedFragment = FavouriteListFragment.getInstance();
                                }
                                break;
                        }
                        fragmentTransactionExecution(savedFragment, fragmentTag);
                        return true;
                    }
                });
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
        transaction.replace(R.id.frame_layout, NeedyFeedyHomeTabFragment.getInstance(), "home");
        transaction.commit();
        getSupportFragmentManager().executePendingTransactions();
    }
private void fragmentTransactionExecution(Fragment selectedFragment, String fragmentTag) {
        if (selectedFragment != null) {
            FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.frame_layout, selectedFragment, fragmentTag);
            transaction.commit();
            getSupportFragmentManager().executePendingTransactions();
        }
    }

【问题讨论】：

大家好，请建议我如何避免在单击选项卡时重新创建片段
您好，请正确格式化您的代码。事实上，人们很难看到它并帮助您解决问题。
标签是你在创建片段时设置的，请发布你的代码来解释你是如何创建片段实例的。

标签： android fragment bottomnavigationview bottombar

【解决方案1】：

在onCreateView的每个片段中添加view.setTag(this);。

【讨论】：