Android viewPager2 + fragment 模拟微信首页1(滑动翻页效果)

效果(半成品)

fragment + viewPager2模拟微信首页1(滑动翻页效果)

实现思路

总结:activity → viewPager → Adapter → fragment → TextView
activity里装viewPager,
viewPager里setAdapter
Adapter里放fragment
fragment里设不同的TextView

一 步骤

step1 导入viewPager2依赖
    implementation 'androidx.viewpager2:viewpager2:1.0.0'
step2 activity_main.xml里写viewpager2标签
step3 创建fragment,修改fragment.xml
step4 Fragment.java
    bundle绑定数据
    设置fragment里面TextView的数据为bundle绑定的数据
step5 新建一个Adapter 继承 FragmentStateAdapter
    实现方法
    创建构造函数
    添加属性List    
step6 MainActivity.java
    viewPager.setAdapter(new Adapter(XX,XX,fragmentList))

二 代码 

step1 导入viewPager2依赖

implementation 'androidx.viewpager2:viewpager2:1.0.0'

 step2 activity_main.xml里写viewpager2标签

step3 创建fragment,修改fragment.xml

 fragment_blank_fragment1.xml

step4 BlankFragment1.java

package com.example.viewpager2fragment;


import android.os.Bundle;
import androidx.fragment.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import java.util.zip.Inflater;


public class BlankFragment1 extends Fragment {


    //bundle 的 key
    private static final String ARG_TEXT = "param1";
    //bundle 的 value
    private String textString;
    View rootView;

    public BlankFragment1(){

    }

    //每次newInstance都会创建一个BlankFragment1
    public static BlankFragment1 newInstance(String param1){
        BlankFragment1 fragment = new BlankFragment1();
        Bundle bundle = new Bundle();
        bundle.putString(ARG_TEXT,param1);
        fragment.setArguments(bundle);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if(getArguments() != null){
            //获取绑定的数据
            textString = getArguments().getString(ARG_TEXT);
        }
    }


    //onCreateView : 创建fragment的UI
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        //防止重复解析,资源浪费
        if(rootView == null){
            rootView = inflater.inflate(R.layout.fragment_blank_fragment1, container, false);
        }
        initView();
        return rootView;
    }

    //设置fragment里面TextView的数据为bundle绑定的数据
    private void initView() {
        TextView textView = rootView.findViewById(R.id.text);
        textView.setText(textString);
    }



}

step5 新建一个Adapter 继承 FragmentStateAdapter

package com.example.viewpager2fragment;


import androidx.annotation.NonNull;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.lifecycle.Lifecycle;
import androidx.viewpager2.adapter.FragmentStateAdapter;

import java.util.List;

public class MyFragmentPagerAdapter extends FragmentStateAdapter {

    List fragmentList;
    public MyFragmentPagerAdapter(@NonNull FragmentManager fragmentManager, @NonNull Lifecycle lifecycle,List fragmentList) {
        super(fragmentManager, lifecycle);
        this.fragmentList = fragmentList;
    }

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

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

step6 MainActivity.java

package com.example.viewpager2fragment;

import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.viewpager2.widget.ViewPager2;

import android.os.Bundle;
import android.view.View;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {


    ViewPager2 viewPager;

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

    //初始化viewPager
    private void initPager() {
        viewPager = findViewById(R.id.viewpager);
        ArrayList fragments =new ArrayList<>();
        fragments.add(BlankFragment1.newInstance("微信聊天"));
        fragments.add(BlankFragment1.newInstance("通讯录"));
        fragments.add(BlankFragment1.newInstance("发现"));
        fragments.add(BlankFragment1.newInstance("我"));
        MyFragmentPagerAdapter myAdapter = new MyFragmentPagerAdapter(getSupportFragmentManager(),getLifecycle(),fragments);
        viewPager.setAdapter(myAdapter);
    }
}

滑动页面和标签的绑定请看这里