第二个参数类型错误。找到：'android.app.Fragment'，需要：'android.support.v4.app.Fragment'

Question

我正在 Youtube 上观看教程视频。我从一开始就做了 2 次完全相同的事情，但仍然停留在那里。我会不断收到此错误，但他没有收到错误。

代码在这里。错误在 private void DisplayFragment class.

下

    package com.example.kenpachi.navigation_drawer;

import android.app.Fragment;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.NavigationView;
import android.support.design.widget.Snackbar;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;


public class MainActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
    drawer.setDrawerListener(toggle);
    toggle.syncState();

    NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
    navigationView.setNavigationItemSelectedListener(this);
}

@Override
public void onBackPressed() {
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START);
    } else {
        super.onBackPressed();
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}


private void DisplayFragment(int id) {

    Fragment fragment = null;
    switch (id) {
        case R.id.nav_one:
            fragment = new FragmentOne();
            break;
        case R.id.nav_two:
            fragment = new FragmentTwo();
            break;
        case R.id.nav_three:
            fragment = new FragmentThree();
    }

    if (fragment != null) {

        android.support.v4.app.FragmentTransaction ft = getSupportFragmentManager().beginTransaction();

        ft.replace(R.id.MyFrameLayout, fragment); // "fragment" gives me this error.

        ft.commit();
    }
}


@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();

    if (id == R.id.nav_camera) {
        // Handle the camera action
    } else if (id == R.id.nav_gallery) {

    } else if (id == R.id.nav_slideshow) {

    } else if (id == R.id.nav_manage) {

    } else if (id == R.id.nav_share) {

    } else if (id == R.id.nav_send) {

    }

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}
}

这是给我错误的行（在 DisplayFragment 中）：

ft.replace(R.id.MyFrameLayout, fragment);

谢谢。如果这里有人感兴趣是我正在尝试做的视频指南：https://youtu.be/iZ8Y7W2jbv8?t=386

Answer 1

替换

import android.app.Fragment;

和

import android.support.v4.app.Fragment;

Answer 2

android 有两种片段

android.app.Fragment
android.support.v4.app.Fragment

因此您必须检查您的 FragmentOne、FragmentTwo.. 您使用的是哪种类型...

例如在 FragmentOne 中使用 import android.app.Fragment 那么您必须在 Activity.

中使用 import android.app.Fragment

或

在 FragmentOne 内部使用 import android.support.v4.app.Fragment 那么您必须在 Activity.

中使用 import android.support.v4.app.Fragment

片段创建和片段调用都必须是同一类型

Answer 3

谢谢大家。当我切换
"import android.app.Fragment;" 到 "android.support.v4.app.Fragment;"
对于 MainActivity 和 FragmentOne-Two-Three，问题消失了。
我之前只为 MainActivity 这样做过，所以我会收到新的错误。
再次感谢。

第二个参数类型错误。找到：'android.app.Fragment'，需要：'android.support.v4.app.Fragment'

Wrong 2nd argument type. Found: 'android.app.Fragment', required: 'android.support.v4.app.Fragment'

android

android-fragments

types

arguments

required