Android ViewPager2 + Fragment + BottomNavigationView 联动

本篇主要介绍一下 ViewPager2 + Fragment + BottomNavigationView , 上篇中把ViewPager2和Fragment 联动起来了, 本篇主要把 BottomNavigationView集成进去 。

概述

BottomNavigationView 是一个底部导航控件, 现在要实现的效果就是 滑动ViewPager2 中的Fragment 并且底部BottomNavigationView 菜单部分跟着联动 同理反过来 点击BottomNavigationView 的时候 ViewPager2中的Fragment 也对应滑动, 下面来看看如何实现的吧 。

实现思路

1.Activity 布局文件中引入 ViewPager2 控件

2. 编写menu文件 提供给BottomNavigationView 用于展示

3.Activity 布局文件中引入BottomNavigationView 控件

4.编写 Fragment 用于填充到ViewPager2中

5. 编写Adapter 实现 FragmentStateAdapter

6.BottomNavigationView添加 setOnItemSelectedListener 联动ViewPager2

7.ViewPager2 添加 registerOnPageChangeCallback 联动 BottomNavigationView

代码实现

下面就来按照上面的思路一步步实现代码啦.

1.Activity 布局文件中引入 ViewPager2 控件

                        
                          <?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ViewPager2BottomActivity">


    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/viewpager2bottom"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toTopOf="@id/bootomnav2"
        />


</androidx.constraintlayout.widget.ConstraintLayout>

                        
                      

2.编写menu文件 提供给BottomNavigationView 用于展示

图标icon 自己配置吧 。

                        
                          <?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">

    <item
        android:title="首页"
        android:id="@+id/home_item"
        android:icon="@drawable/ic_baseline_home_24"
        />

    <item
        android:title="类型"
        android:id="@+id/type_item"
        android:icon="@drawable/ic_baseline_merge_type_24"
        />

    <item
        android:title="添加"
        android:id="@+id/add_item"
        android:icon="@drawable/ic_baseline_add_24"
        />

    <item
        android:title="设置"
        android:id="@+id/setting_item"
        android:icon="@drawable/ic_baseline_settings_24"
        />
</menu>

                        
                      

3.Activity 布局文件中引入BottomNavigationView 控件

                        
                          package com.johnny.slzzing;

import android.os.Bundle;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import org.w3c.dom.Text;

/**
 * A simple {@link Fragment} subclass.
 * Use the {@link Bottom2Fragment#newInstance} factory method to
 * create an instance of this fragment.
 */
public class Bottom2Fragment extends Fragment {

    // TODO: Rename parameter arguments, choose names that match
    // the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
    private static final String ARG_PARAM1 = "param1";
    private static final String ARG_PARAM2 = "param2";

    // TODO: Rename and change types of parameters
    private String mParam1;
    private String mParam2;

    public Bottom2Fragment() {
        // Required empty public constructor
    }

    /**
     * Use this factory method to create a new instance of
     * this fragment using the provided parameters.
     *
     * @param param1 Parameter 1.
     * @param param2 Parameter 2.
     * @return A new instance of fragment Bottom2Fragment.
     */
    // TODO: Rename and change types and number of parameters
    public static Bottom2Fragment newInstance(String param1, String param2) {
        Bottom2Fragment fragment = new Bottom2Fragment();
        Bundle args = new Bundle();
        args.putString(ARG_PARAM1, param1);
        args.putString(ARG_PARAM2, param2);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_PARAM1);
            mParam2 = getArguments().getString(ARG_PARAM2);
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_bottom2, container, false);
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        TextView textView = view.findViewById(R.id.textview2);
        //把动态传入的参数设置到 textView上
        textView.setText(mParam1);
    }
}

                        
                      

fragment_bottom2.xml 。

                        
                          <?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ViewPager2BottomActivity">


    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/viewpager2bottom"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toTopOf="@id/bootomnav2"
        />

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/bootomnav2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintTop_toBottomOf="@id/viewpager2bottom"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:menu="@menu/bottom_item_menu"                                        
        app:labelVisibilityMode="labeled" 
        />
<!-- 这个要设置 app:labelVisibilityMode="labeled"  才能显示图标文字 因为我这里超过了3个-->        
</androidx.constraintlayout.widget.ConstraintLayout>

                        
                      

4.编写 Fragment 用于填充到ViewPager2中

                        
                          <?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    tools:context=".Bottom2Fragment">

    <!-- TODO: Update blank fragment layout -->
    <TextView
        android:id="@+id/textview2"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="@string/hello_blank_fragment"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        android:gravity="center"
        android:textSize="25sp"
        android:textStyle="bold"
        android:textColor="@color/black"
        />

</androidx.constraintlayout.widget.ConstraintLayout>

                        
                      

5. 编写Adapter 实现 FragmentStateAdapter

上篇已经说过了 直接继承 FragmentStateAdapter 。

                        
                          class MyViewPager2BottomAdapter extends FragmentStateAdapter {

    List<Fragment> fragmentList;
    public MyViewPager2BottomAdapter(@NonNull FragmentActivity fragmentActivity, List<Fragment> list) {
        super(fragmentActivity);
        this.fragmentList = list;
    }

    @NonNull
    @Override
    public Fragment createFragment(int position) {
        return fragmentList.get(position);
    }

    @Override
    public int getItemCount() {
        return fragmentList.size();
    }
}

                        
                      

6.BottomNavigationView添加 setOnItemSelectedListener 联动ViewPager2

bottomNavigationView.setOnItemSelectedListener核心方法 。

Acitivity 中实现如下代码

                        
                            protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_view_pager2_bottom);

        viewPager2 = findViewById(R.id.viewpager2bottom);
        bottomNavigationView = findViewById(R.id.bootomnav2);
        MyViewPager2BottomAdapter myViewPager2BottomAdapter =
                new MyViewPager2BottomAdapter(this,initFragmentList());
        viewPager2.setAdapter(myViewPager2BottomAdapter);
        //重点 设置 bottomNavigationView 的item 的点击事件 设置viewPager2的联动
        bottomNavigationView.setOnItemSelectedListener(new NavigationBarView.OnItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                int itemId = item.getItemId();
                switch (itemId){
                    case R.id.home_item:
                        viewPager2.setCurrentItem(0);
                        break;
                    case R.id.type_item:
                        viewPager2.setCurrentItem(1);
                        break;
                    case R.id.add_item:
                        viewPager2.setCurrentItem(2);
                        break;
                    case R.id.setting_item:
                        viewPager2.setCurrentItem(3);
                        break;
                }
                return true;
            }
        });

    }

                        
                      

7.ViewPager2 添加 registerOnPageChangeCallback 联动 BottomNavigationView

                        
                          protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_view_pager2_bottom);

    viewPager2 = findViewById(R.id.viewpager2bottom);
    bottomNavigationView = findViewById(R.id.bootomnav2);
    MyViewPager2BottomAdapter myViewPager2BottomAdapter =
            new MyViewPager2BottomAdapter(this,initFragmentList());
    viewPager2.setAdapter(myViewPager2BottomAdapter);

    bottomNavigationView.setOnItemSelectedListener(new NavigationBarView.OnItemSelectedListener() {
        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem item) {
            int itemId = item.getItemId();
            switch (itemId){
                case R.id.home_item:
                    viewPager2.setCurrentItem(0);
                    break;
                case R.id.type_item:
                    viewPager2.setCurrentItem(1);
                    break;
                case R.id.add_item:
                    viewPager2.setCurrentItem(2);
                    break;
                case R.id.setting_item:
                    viewPager2.setCurrentItem(3);
                    break;
            }
            return true;
        }
    });
     //重点 实现滑动的时候 联动 bottomNavigationView的selectedItem
    viewPager2.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {
        @Override
        public void onPageSelected(int position) {
            super.onPageSelected(position);
            switch (position){
                case 0:
                    bottomNavigationView.setSelectedItemId(R.id.home_item);
                    break;
                case 1:
                    bottomNavigationView.setSelectedItemId(R.id.type_item);
                    break;
                case 2:
                    bottomNavigationView.setSelectedItemId(R.id.add_item);
                    break;
                case 3:
                    bottomNavigationView.setSelectedItemId(R.id.setting_item);
                    break;
            }
        }
    });

}

                        
                      

总结

本篇主要介绍了 如何把ViewPager2 + Fragment + BottomNavigationView 集成起来并且实现ViewPager2和BottomNavigationView的双向联动 。

ViewPager和ViewPager2 一些区别

• ViewPager 的 Adapter 继承 FragmentStatePagerAdapter 而 ViewPager2 的Adapter 继承 FragmentStateAdapter
• ViewPager 滑动监听是 viewPager.addOnPageChangeListener方法 而ViewPager2 滑动监听是 registerOnPageChangeCallback 方法

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