如何将片段添加到列表

Question

我创建了以下包：

首页 -> HomeActivity.class,HomeFragment.class,SectionsPageAdapter.class

好友 -> Friends.class

消息 -> Messages.class

SectionsPageAdapter 扩展了 FragmentPagerAdapter 来管理片段， SectionsPageAdapter中写的代码是：

    package com.example.sk.voiceapplication.HomePage;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;

import java.util.ArrayList;
import java.util.List;

public class SectionsPageAdapter extends FragmentPagerAdapter {

    private final List<Fragment> fragment_hierarchy = new ArrayList<>();

    public SectionsPageAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        return fragment_hierarchy.get(position);
    }

    @Override
    public int getCount() {
        return fragment_hierarchy.size();
    }
    public void addFragment(Fragment fragment){
        fragment_hierarchy.add(fragment);
    }
}

Class 主页片段:

    package com.example.sk.voiceapplication.HomePage;

import android.app.Fragment;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.Toast;

import com.example.sk.voiceapplication.R;


public class HomeFragment extends Fragment {
    private static final String TAG = "HomeFragment";

    private Button btn_test;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.home_fragment,container,false);
        btn_test = (Button) view.findViewById(R.id.button2);
        btn_test.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {
                Toast.makeText(getActivity(),"Testing Button Click 2", Toast.LENGTH_SHORT).show();
            }
        });
        return view;
    }
}

现在 Class Friends 和 Messages 与 HomeFragment 相同，但需要进行一些小改动在 class HomeActivity 我写了：

    package com.example.sk.voiceapplication.HomePage;

import android.content.Intent;
import android.support.annotation.NonNull;
import android.support.design.widget.TabLayout;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;

import com.example.sk.voiceapplication.Friends.Friends;
import com.example.sk.voiceapplication.Messages.Messages;
import com.example.sk.voiceapplication.Profile.MyProfile;
import com.example.sk.voiceapplication.R;

public class HomeActivity extends AppCompatActivity {

    private static final String TAG = "HomeActivity";

    private SectionsPageAdapter sectionsPagerAdapter;
    private ViewPager viewPager;

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

    private void setupFragments() {
        sectionsPagerAdapter = new SectionsPageAdapter(getSupportFragmentManager());
        viewPager = (ViewPager) findViewById(R.id.container);
        setupViewPager(viewPager);
        TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(viewPager);
        tabLayout.getTabAt(0);
        tabLayout.getTabAt(1);
        tabLayout.getTabAt(2);
    }

    private void setupViewPager(ViewPager viewPager) {
        SectionsPageAdapter adapter = new SectionsPageAdapter(getSupportFragmentManager());
        adapter.addFragment(new HomeFragment());
        adapter.addFragment(new Messages());
        adapter.addFragment(new Friends());
        viewPager.setAdapter(adapter);
    }
}

在 HomeActivity 中，当我创建 Fragments 对象并使用 Line

将它们添加到 SectionsPageAdapter 时

adapter.addFragment(new HomeFragment());

显示错误：

SectionsPageAdapter 中的

addFragment(android.support.v4.app.Fragment) 无法应用于 (com.example.sk.voiceapplication.HomePage.HomeFragment)

与

类似

adapter.addFragment(新消息());

SectionsPageAdapter 中的

addFragment(android.support.v4.app.Fragment) 无法应用于 (com.example.sk.voiceapplication.Messages.Messages)

adapter.addFragment(新朋友());

SectionsPageAdapter 中的

addFragment(android.support.v4.app.Fragment) 无法应用于 (com.example.sk.voiceapplication.Friends.Friends)

我做错了什么？解决方法是什么？

Answer 1

您缺少导入 import android.support.v4.app.Fragment;。您必须使用 V4 片段而不是 android.app.Fragment.

替换-:

import android.app.Fragment;

收件人-:

import android.support.v4.app.Fragment; 在你所有的片段中。

Answer 2

将此更改为-：

public class HomeFragment extends Fragment

{

}

至-:

public class HomeFragment extends android.support.v4.app.Fragment

{


}

在你所有的三个片段中

如何将片段添加到列表

How to add a Fragment to List

android

fragment

android-fragments

fragmentpageradapter