我正在處理帶有兩個(gè)不同片段的導(dǎo)航抽屜。不起作用的是下面的java文件中的“ first”和“ second”fragmentManager.beginTransaction().replace(R.id.fragment, first).commit();以及另一行中的“ ”和“ ” 。它引發(fā)的錯(cuò)誤是：Wrong 2nd argument type. Found: 'com.example.name_of_app.First', required: 'android.support.v4.app.Fragment' replace(int,android.support.v4.app.Fragment)in FragmentTransaction cannot be appliedto(int,com.example.name_of_app.First) 引發(fā)問題的 MainActivity.java 文件部分：public boolean onNavigationItemSelected(MenuItem item) {        // Handle navigation view item clicks here.        int id = item.getItemId();        if (id == R.id.nav_camera) {            setTitle("First Fragment");            First first = new First();            FragmentManager fragmentManager = getSupportFragmentManager();            fragmentManager.beginTransaction().replace(R.id.fragment, first).commit();        } else if (id == R.id.nav_gallery) {            setTitle("Second Fragment");            Second second = new Second();            FragmentManager fragmentManager = getSupportFragmentManager();            fragmentManager.beginTransaction().replace(R.id.fragment, second).commit();        } 這是 First.java 片段import android.os.Bundle;import android.app.Fragment;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;/** * A simple {@link Fragment} subclass. */public class First extends Fragment {    public First() {        // Required empty public constructor    }    @Override    public View onCreateView(LayoutInflater inflater, ViewGroup container,                             Bundle savedInstanceState) {        // Inflate the layout for this fragment        return inflater.inflate(R.layout.fragment_first, container, false);    }}