Android Can'；无法使用Bottomnavigationview正确加载片段

我遵循了下面的教程，但我一直无法从收藏夹片段（bottomnavigationview上的中间图标）开始加载它

我什么都试过了，到处都找遍了

我的应用程序将始终加载喜爱的文本，但在我选择图标之前，底部导航视图将始终突出显示主页图标

当收藏夹图标高亮显示且处于空状态时，如何使应用程序打开并显示收藏夹片段

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在MainActivity中，替换以下内容：

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

        BottomNavigationView bottomNav = findViewById(R.id.bottom_navigation);
        bottomNav.setOnNavigationItemSelectedListener(navListener);

        //I added this if statement to keep the selected fragment when rotating the device
        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
                    new HomeFragment()).commit();
        }
    }

为此：

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

        BottomNavigationView bottomNav = findViewById(R.id.bottom_navigation);
        bottomNav.setOnNavigationItemSelectedListener(navListener);

        //I added this if statement to keep the selected fragment when rotating the device
        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,
                    new HomeFragment()).commit();
        }

        bottomNav.setSelectedItemId(R.id.nav_favorites);
    }

我们基本上只是将这一行添加到onCreate（）函数的末尾：

bottomNav.setSelectedItemId(R.id.nav_favorites);