Android ViewPager2 load once when fast scroll many page，Java

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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"
    tools:context=".MainActivity">

    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</RelativeLayout>

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentActivity;
import androidx.viewpager2.adapter.FragmentStateAdapter;
import androidx.viewpager2.widget.ViewPager2;

import android.os.Bundle;
import android.util.Log;

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

public class MainActivity extends AppCompatActivity {
    private String TAG = "fly";

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

        ViewPager2 viewPager2 = findViewById(R.id.viewpager);

        final List<Fragment> fragments = new ArrayList<>();
        for (int i = 0; i < 999; i++) {
            Fragment fragment = new TestFrgment("fragment" + i);
            fragments.add(fragment);
        }

        MyFragmentAdapter adapter = new MyFragmentAdapter(this, fragments);
        viewPager2.setAdapter(adapter);

        viewPager2.registerOnPageChangeCallback(new LazyOnPageChangeCallback(){
            @Override
            public void selectedPage(int pos) {
                pageSelected(pos);
            }
        });
    }

    private void pageSelected(int pos) {
        Log.d(TAG, "-");
        Log.d(TAG, "选中:" + pos);
        Log.d(TAG, "--");
    }

    private class MyFragmentAdapter extends FragmentStateAdapter {
        private List<Fragment> fragments;

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

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

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

import android.os.Handler;
import android.os.Looper;
import android.os.Message;

import androidx.annotation.NonNull;
import androidx.viewpager2.widget.ViewPager2;

public class LazyOnPageChangeCallback extends ViewPager2.OnPageChangeCallback {
    private long DELAY_TIME = 400L;

    private int mCurPos = 0;

    private int CHANGE_MSG_WHAT = 0xff01;

    public void selectedPage(int pos) {

    }

    private Handler mLoad = new Handler(Looper.getMainLooper()) {
        @Override
        public void handleMessage(@NonNull Message msg) {
            if (msg.what == CHANGE_MSG_WHAT) {
                removeMessages(CHANGE_MSG_WHAT);
                selectedPage(mCurPos);
            }
        }
    };

    @Override
    public void onPageSelected(int position) {
        super.onPageSelected(position);
        mCurPos = position;
        //viewpager首次加载触发selectedPage()
        mLoad.sendEmptyMessageDelayed(CHANGE_MSG_WHAT, DELAY_TIME);
    }

    @Override
    public void onPageScrollStateChanged(int state) {
        super.onPageScrollStateChanged(state);
        if (state == ViewPager2.SCROLL_STATE_DRAGGING) {
            mLoad.removeMessages(CHANGE_MSG_WHAT);
        } else if (state == ViewPager2.SCROLL_STATE_IDLE) {
            mLoad.sendEmptyMessageDelayed(CHANGE_MSG_WHAT, DELAY_TIME);
        }
    }
}

import android.os.Bundle;
import android.util.Log;
import android.util.TypedValue;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.core.content.ContextCompat;
import androidx.fragment.app.Fragment;

public class TestFrgment extends Fragment {
    private String tag;

    private String LOG = "生命周期->";

    public TestFrgment(String tag) {
        this.tag = tag;
    }

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.d(LOG + tag, "onCreate");
    }

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        TextView text = new TextView(getContext());
        text.setText(tag);
        text.setTextSize(TypedValue.COMPLEX_UNIT_DIP, 80);
        text.setTextColor(ContextCompat.getColor(getContext(), android.R.color.holo_red_dark));
        return text;
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        Log.d(LOG + tag, "onViewCreated");
    }

    @Override
    public void onStart() {
        super.onStart();
        Log.d(LOG + tag, "onStart");
    }

    @Override
    public void onResume() {
        super.onResume();
        Log.d(LOG + tag, "onResume");
    }

    @Override
    public void onPause() {
        super.onPause();
        Log.d(LOG + tag, "onPause");
    }

    @Override
    public void onStop() {
        super.onStop();
        Log.d(LOG + tag, "onStop");
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        Log.d(LOG + tag, "onDestroy");
    }
}

ViewPager2和Fragment可见性及懒加载解决方案_zhangphil的博客-CSDN博客ViewPager2和Fragment新的可见性及懒加载解决方案，旨在解决ViewPager（ViewPager2）只有当前Fragment唯一可见时候网络刷新或绘图。注意：过去的setUserVisibleHint()已被废弃，开发者不要再使用基于setUserVisibleHint()解决Fragment可见性和懒加载（或延迟加载）的场景。新方案用最新的ViewPager2替代过去旧版的ViewPager，再结合Fragment的resume和pause生命周期实现。写一个demo例子，测试的主类Mhttps://blog.csdn.net/zhangphil/article/details/108893237