RecyclerView系列（四）固定條數中獎信息輪播切換

效果圖

實現原理

1、比如說一共10條數據，顯示的條目是5，所以在RecyclerView的adapter的getItemCount（）方法返回的數值就應該是5，其他的都不用更改。

2、要讓這些數據切換，需要寫一個定時任務ScheduledExecutorService每隔固定時間切換數據顯示。

3、數據的切換效果通過adapter的notifyItemRangeRemoved（）進行。

代碼一覽

Adapter代碼

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import com.example.zpf.animmenu.R;

import java.util.ArrayList;

/**
 * 中獎信息輪播切換的Adapter
 */

public class RvAdapterPrizeInfo extends RecyclerView.Adapter<RvAdapterPrizeInfo.PrizeInfoViewHolder> {

    private Context mContext;
    private ArrayList<String> prizeList = new ArrayList<>();

    public RvAdapterPrizeInfo(Context context) {

        this.mContext = context;
    }

    public void setList(ArrayList<String> list) {

        if (list != null && !list.isEmpty()) {

            this.prizeList = list;
            notifyDataSetChanged();
        }
    }

    public void updateList() {

        if (!prizeList.isEmpty()) {

            prizeList.add(prizeList.get(0));
            prizeList.remove(0);
            notifyItemRangeRemoved(0, 1);
        }
    }

    @Override
    public PrizeInfoViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {

        View view = LayoutInflater.from(viewGroup.getContext())
                .inflate(R.layout.item_prize_info, viewGroup, false);
        return new PrizeInfoViewHolder(view);
    }

    @Override
    public void onBindViewHolder(PrizeInfoViewHolder holder, int i) {

        String info = prizeList.get(i);
        holder.tv.setText(info);

    }

    @Override
    public int getItemCount() {
        return 5;
    }

    class PrizeInfoViewHolder extends RecyclerView.ViewHolder{

        private TextView tv;

        PrizeInfoViewHolder(View itemView) {
            super(itemView);

            tv = (TextView) itemView.findViewById(R.id.tv_prize_info);
        }
    }
}

ViewHolder佈局xml代碼

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <TextView
        android:id="@+id/tv_prize_info"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:lines="1"
        android:textSize="14sp"
        android:textColor="#565656"/>

</LinearLayout>

Activity實現代碼

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;

import java.util.ArrayList;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

import adapter.RvAdapterPrizeInfo;

public class RecyclerPrizeInfoActivity extends AppCompatActivity {

    private RvAdapterPrizeInfo adapter;

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

        initView();
    }

    private void initView() {

        RecyclerView recyclerView = (RecyclerView) findViewById(R.id.rv_prize_info);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setHasFixedSize(true);

        ArrayList<String> strings = new ArrayList<>();
        for (int i=0; i<10; i++) {

            strings.add("恭喜***抽中" + (i*2) + "元紅包！");
        }

        adapter = new RvAdapterPrizeInfo(this);
        recyclerView.setAdapter(adapter);
        adapter.setList(strings);

        ScheduledExecutorService ses = Executors.newSingleThreadScheduledExecutor();
        ses.scheduleAtFixedRate(new Runnable() {
            @Override
            public void run() {

                adapter.updateList();
            }
        }, 2000, 2000, TimeUnit.MILLISECONDS);
    }
}

Activity界面佈局xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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="com.example.zpf.animmenu.RecyclerPrizeInfoActivity">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/rv_prize_info"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:background="#FDE480"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

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That’s all ! Thank you ! 有興趣就去copy代碼試試吧