片段管理器事务错误的参数类型

Question

我正在处理带有两个不同片段的导航抽屉。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“ ” 。它引发的错误是：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) 引发问题的 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();        } 这是 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);    }}

Answer 1

如果您查看错误，您会看到android.support.v4.app.Fragment. 但是，您的课程First具有import android.app.Fragment;导入功能。

他们不匹配。将导入更改为import android.support.v4.app.Fragment;