《你的第一行Android代码》菜鸡的自学日记-第十天

ListView 进化！更加强大的 RecyclerView！

一、用 RecyclerView 做 ListView 做过的：

1.添加依赖

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:24.2.1'
    
    compile'com.android.support:recyclerview-v7:24.2.1'			//添加的依赖库
    
    testCompile 'junit:junit:4.12'
}

2.与 ListView 示例相同的图片、Fruit 类、fruit_item.xml。

新建 FruitAdapter 类，让这个适配器继承自 RecyclerView.Adapter ，指定泛型 FruitAdapter.ViewHolder 。ViewHolder 是在一个内部类。

public class FruitAdapter extends RecyclerView.Adapter<FruitAdapter.ViewHolder> {

    private List<Fruit>mFruitList;

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

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

    }


    public FruitAdapter(List<Fruit>fruitList){
        mFruitList = fruitList;
    }

    public ViewHolder onCreateViewHolder(ViewGroup parent,int viewType){
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.fruit_item,parent,false);
        ViewHolder holder = new ViewHolder(view);
        return holder;
    }

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

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


}

修改MainActivity中的代码：

private List<Fruit> 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);
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        recyclerView.setLayoutManager(layoutManager);
        FruitAdapter adapter = new FruitAdapter(fruitList);
        recyclerView.setAdapter(adapter);
    }

二、ListView 所实现不了的

横向滚动：

修改 fruit_item.xml 中的代码：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="100dp"
    android:layout_height="match_parent">

    <ImageView
        android:id="@+id/fruit_img"
        android:layout_width="60dip"
        android:layout_height="60dip"
        android:layout_gravity="center_horizontal"/>
    <TextView
        android:id="@+id/fruit_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:layout_marginTop="10dp"
        />

</LinearLayout>

修改 MainActivity 中的代码：

 protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initFruits();
        RecyclerView recyclerView = (RecyclerView)findViewById(R.id.recycler_view);
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);

        layoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);	//让布局横行排列

        recyclerView.setLayoutManager(layoutManager);
        FruitAdapter adapter = new FruitAdapter(fruitList);
        recyclerView.setAdapter(adapter);
    }

炫酷的瀑布流布局：

修改 fruti_item.xml 中的代码：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_margin="5dp">

    <ImageView
        android:id="@+id/fruit_img"
        android:layout_width="60dip"
        android:layout_height="60dip"
        android:layout_gravity="center_horizontal"/>
    <TextView
        android:id="@+id/fruit_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="left"
        android:layout_marginTop="10dp"
        />

</LinearLayout>

修改 MainActivtiy 中的代码：

public class MainActivity extends AppCompatActivity {

    private List<Fruit> 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.apple_pic);
           fruitList.add(apple);
            Fruit banana = new Fruit(getRandomLengthName("Banana"),R.drawable.banana_pic);
            fruitList.add(banana);
            Fruit orange= new Fruit(getRandomLengthName("Orange"),R.drawable.orange_pic);
            fruitList.add(orange);
            Fruit watermelon= new Fruit(getRandomLengthName("Watermelon"),R.drawable.watermelon_pic);
            fruitList.add(watermelon);
            Fruit pear= new Fruit(getRandomLengthName("Pear"),R.drawable.pear_pic);
            fruitList.add(pear);
            Fruit grape= new Fruit(getRandomLengthName("Grape"),R.drawable.grape_pic);
            fruitList.add(grape);
            Fruit cherry= new Fruit(getRandomLengthName("Cherry"),R.drawable.cherry_pic);
            fruitList.add(cherry);
            Fruit mango= new Fruit(getRandomLengthName("Mango"),R.drawable.mango_pic);
            fruitList.add(mango);
            Fruit strawberry= new Fruit(getRandomLengthName("Strawberry"),R.drawable.strawberry_pic);
            fruitList.add(strawberry);

        }
    }

    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();
    }
}

效果图：

RecyclerView 的点击事件：

RecyclerView 没有 setOnItemClickListener（）这样的注册监听器方法，需要自己给子项具体的 view 去注册点击事件。

修改 FruitAdapter 中的代码：

public class FruitAdapter extends RecyclerView.Adapter<FruitAdapter.ViewHolder> {

    private List<Fruit>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_img);
            fruitName = (TextView)view.findViewById(R.id.fruit_name);
        }

    }

    public FruitAdapter(List<Fruit>fruitList){
        mFruitList = fruitList;
    }

    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(),"u 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(),"u clikde image"+fruit.getName(),Toast.LENGTH_SHORT).show();
            }
        });

        return holder;
    }

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

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


}

小结：了解了 RecyclerView 的基本操作，觉得瀑布流布局真的好看，觉得最近学的有点囫囵吞枣，接下来几天应该加深理解这十天学的东西，暂停学习新的知识。