【android】recycleview小整理

RecyclerView

我梦想着打造一个不需要新建类的recycleviewqwq
compile ‘com.android.support:recyclerview-v7:24.2.1’

• 我们先看这个之前的网站吧。
  https://github.com/newcaoguo/booksource/blob/master/chapter3/RecyclerViewTest/app/src/main/java/com/example/recyclerviewtest/MainActivity.java 源码（FruitAdpter
• 这个封装思想会好一些，fruit类里面是name imageid
• 我们自定义了适配器，是一个新的类。FruitAdapter 类，继承自RecyclerView.Adapter ，泛型 就是括号里面 是FruitAdapter.ViewHolder
• 这个泛型 在后面它是个内部类。这个ViewHolder内部类也继承了 RecyclerView.ViewHolder

1 代码解析

① ViewHolder 的构造函数中要传入一个View 参数，这个参数通常就是RecyclerView子项的最外层布局 通过从最外层布局入手找到里面那俩~ qwq 所以①处的代码先是继承，然后找到了其他两
② 这个类本身的构造函数 用于把要展示的数据源传进来，并赋值给一个全局变量mFruitList ，我们后续的操作都将在这个数据源的基础上进行。类型为List 还封装的挺好qwq
③ 由于是继承的之前的adapter， 所以剩下三个都是在重写了饿
onCreateViewHolder() 方法是用于创建ViewHolder 实例的，我们在这个方法中将fruit_item 布局加载进来，然后创建一个ViewHolder 实例，并把加载出来的布局传入到构造函数当中，最后将ViewHolder 的实例返回
onBindViewHolder() 方法是用于对RecyclerView子项的数据进行赋值的，会在每个子项被滚动到屏幕内的时候执行，这里我们通过position 参数得到当前项的Fruit 实例，然后再将数据设置到ViewHolder 的ImageView和TextView当中即可。
getItemCount()是有多少子项

2 再看主类

private List fruitList = new ArrayList<>();
....
initFruits(); // 初始化水果数据
        RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        recyclerView.setLayoutManager(layoutManager);
        FruitAdapter adapter = new FruitAdapter(fruitList);
        recyclerView.setAdapter(adapter);

或者 StaggeredGridLayoutManager layoutManager = new
StaggeredGridLayoutManager(3, StaggeredGridLayoutManager.VERTICAL);
recyclerView.setLayoutManager(layoutManager);

3 子项点击事件

onCreateViewHolder里面
之前是把holder实例化并加载了布局，现在可以进一步搞这个holder。给它注册点击事件，然后判断你点了啥。这里，是分开设置点击事件的，也就是说

• 先 在内部类里写了 View fruitView;
  ImageView fruitImage;
  TextView fruitName;
• 随后holder.fruitVieiw.seton… holder.fruitname.seton… 分别写各自的监听事件就好啦.

4 进行实战

我真傻，我单知道…… 那是因为没有图片地址啊啊

最后的 适配器代码

package com.example.mol74.recycleviewdemo;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import java.util.List;

public class FruitAdapter extends RecyclerView.Adapter{

    private List mFruitList;

    static class ViewHolder extends RecyclerView.ViewHolder {
        View fruitView;
        ImageView fruitImage;
        TextView fruitName;

        public ViewHolder(View view) {
            super(view);
            fruitView = view;
            fruitImage = (ImageView) view.findViewById(R.id.fruit_image);
            fruitName = (TextView) view.findViewById(R.id.fruit_name);
        }
    }

    public FruitAdapter(List fruitList) {
        mFruitList = fruitList;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.fruit_item, parent, false);
        final ViewHolder holder = new ViewHolder(view);
        holder.fruitView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int position = holder.getAdapterPosition();
                Fruit fruit = mFruitList.get(position);
                Toast.makeText(v.getContext(), "you clicked view " + fruit.getName(), Toast.LENGTH_SHORT).show();
            }
        });
        holder.fruitImage.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int position = holder.getAdapterPosition();
                Fruit fruit = mFruitList.get(position);
                Toast.makeText(v.getContext(), "you clicked image " + fruit.getName(), Toast.LENGTH_SHORT).show();
            }
        });
        return holder;
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        Fruit fruit = mFruitList.get(position);
        holder.fruitImage.setImageResource(fruit.getImageId());
        holder.fruitName.setText(fruit.getName());
    }

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

}

Main函数 … 这个下面好多是没用的

package com.example.mol74.recycleviewdemo;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;

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

public class MainActivity extends AppCompatActivity {

    private List fruitList = new ArrayList();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initFruits();
        RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
        StaggeredGridLayoutManager layoutManager = new
                StaggeredGridLayoutManager(3, StaggeredGridLayoutManager.VERTICAL);
        recyclerView.setLayoutManager(layoutManager);
        FruitAdapter adapter = new FruitAdapter(fruitList);
        recyclerView.setAdapter(adapter);
    }

    private void initFruits() {
        for (int i = 0; i < 2; i++) {
            Fruit apple = new Fruit(getRandomLengthName("Apple"), R.drawable.ic_launcher_background);
            fruitList.add(apple);
            Fruit banana = new Fruit(getRandomLengthName("Banana"), R.drawable.ic_launcher_foreground);
            fruitList.add(banana);
            Fruit orange = new Fruit(getRandomLengthName("Orange"), R.drawable.ic_launcher_foreground);
            fruitList.add(orange);
            Fruit watermelon = new Fruit(getRandomLengthName("Watermelon"), R.drawable.ic_launcher_foreground);
            fruitList.add(watermelon);
            Fruit pear = new Fruit(getRandomLengthName("Pear"), R.drawable.ic_launcher_foreground);
            fruitList.add(pear);
            Fruit grape = new Fruit(getRandomLengthName("Grape"), R.drawable.ic_launcher_foreground);
            fruitList.add(grape);
            Fruit pineapple = new Fruit(getRandomLengthName("Pineapple"), R.drawable.ic_launcher_foreground);
            fruitList.add(pineapple);
            Fruit strawberry = new Fruit(getRandomLengthName("Strawberry"), R.drawable.ic_launcher_foreground);
            fruitList.add(strawberry);
            Fruit cherry = new Fruit(getRandomLengthName("Cherry"), R.drawable.ic_launcher_foreground);
            fruitList.add(cherry);
            Fruit mango = new Fruit(getRandomLengthName("Mango"), R.drawable.ic_launcher_foreground);
            fruitList.add(mango);
        }
    }

    private String getRandomLengthName(String name) {
        Random random = new Random();
        int length = random.nextInt(20) + 1;
        StringBuilder builder = new StringBuilder();
        for (int i = 0; i < length; i++) {
            builder.append(name);
        }
        return builder.toString();
    }

}

fruit只有类和 get方法-.-不写了

https://www.jianshu.com/p/cde0b4d19f64 在这里。子项的监听不能用于启动活动，需要写个接口，因为adapter不是活动嘛，，，他只是个类，用接口在main里用