Android SplashFragment无法使用FragmentManager

runSplash（）永远不会在代码中被调用

您可以通过

fragmentManager=getSupportFragmentManager（）修复
fragmentManager
行。从表面上看，它似乎并不存在。
public class MainActivity extends AppCompatActivity {
    FragmentManager fragmentManager;

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

        fragmentManager = getFragmentManager();
    }

    public void runSplash() {
        SplashFragment splashFragment = new SplashFragment();
        fragmentManager.beginTransaction()
                .replace(R.id.container, splashFragment)
                .addToBackStack(null)
                .commit();
    }
}