我的导航底部栏不能处于其他活动中

Question

我想了解如何在另一个活动中获取导航底部栏。

我尝试了此方法，但仍然无法使用：

MainActivity：

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        BottomNavigationView navView = findViewById(R.id.nav_view);
        mTextMessage = findViewById(R.id.message);
        navView.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
    }

}

这是我的其他活动：

    private TextView mTextMessage;

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

        BottomNavigationView navView = findViewById(R.id.nav_view);
        mTextMessage = findViewById(R.id.message);
        navView.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener); // not working actually...
    }
}

我的日志：

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.design.widget.BottomNavigationView.setOnNavigationItemSelectedListener(android.support.design.widget.BottomNavigationView$OnNavigationItemSelectedListener)