Android adapter进阶

最近碰到一个需求，需要RecyclerView的list里加载不同形式的item；于是便需要adapter加载不同形式的ViewHolder。

Adapter类

//定义一个Object型的List
 List<Object> beans;

//初始化构造器

public ExampleAdapter(Context context, List<Object> beans) {
    this.context = context;
    this.beans = beans;
}

//根据viewType 加载不同的ViewHolder

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        if (viewType == 0) {
            return new ViewHolder1(LayoutInflater.from(context).inflate(R.layout.adapter_1, parent, false));
        } else if (viewType == 1) {
            return new ViewHolder2(LayoutInflater.from(context).inflate(R.layout.adapter_2, parent, false));
        }
        return null;
    }

//定义ViewHolder1 ViewHolder2

public class ViewHolder1 extends RecyclerView.ViewHolder {
        @BindView(R.id.text_example1)
        TextView text_example1;

        public HouseTypeViewHolder(View itemView) {
            super(itemView);
            ButterKnife.bind(this, itemView);
        }
    }

public class ViewHolder2 extends RecyclerView.ViewHolder {
        @BindView(R.id.text_example2)
        TextView text_example2;

        public HouseTypeViewHolder(View itemView) {
            super(itemView);
            ButterKnife.bind(this, itemView);
        }
    }

//根据传入的item，判断加载哪个viewHolder，若匹配到的Object是model1类型 则返回的viewType为0，若匹配到的是model2，则返回1，onBindViewHolder会根据此处的返回值加载不同的ViewHolder

@Override
    public int getItemViewType(int position) {
        if (beans.get(position) instanceof Model1) {
            return 0;
        } else if (beans.get(position) instanceof Model2) {
            return 1;
        }
        return super.getItemViewType(position);
    }

//构造具体view

@Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        if (getItemViewType(position) == 0) {
            ((ViewHolder1) holder).view_example1.setText("example1");
        } else {
            ((ViewHolder2) holder).view_example2.setText("example2");
        }
    }

Activity类

protected ExampleAdapter exampleAdapter;
private List<Object> model;

//初始化
model = new ArrayList<>();
exampleAdapter= new ExampleAdapter(Activity.this, model);
rv_recyclerview.setAdapter(exampleAdapter);

//实现处根据需求，list add不同model
if (page == 1) {
    model.add(Model1实例);
    model.addAll(Model2实例);
} else {
     model.addAll(Model2实例);
}
 exampleAdapter.notifyDataSetChanged();
``` java