RecyclerView1

package com.qianqian.liqianqiandemo1;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.support.v7.widget.GridLayoutManager;import android.support.v7.widget.LinearLayoutManager;import android.support.v7.widget.RecyclerView;import android.support.v7.widget.StaggeredGridLayoutManager;import android.view.View;import android.view.ViewGroup;import android.widget.ImageView;import android.widget.LinearLayout;import android.widget.TextView;import java.util.ArrayList;import java.util.List;public class MainActivity extends AppCompatActivity {   RecyclerView rlv;    List<String> data=new ArrayList<String>();    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        //找到recyclelview        //第一种        rlv= (RecyclerView) findViewById(R.id.rlv);      /*  LinearLayoutManager mar=new LinearLayoutManager(this);        mar.setOrientation(LinearLayoutManager.VERTICAL);        rlv.setLayoutManager(mar);*/        //第二种     //  GridLayoutManager mar=new GridLayoutManager(this,3);        //第三种        StaggeredGridLayoutManager mar = new StaggeredGridLayoutManager(3, StaggeredGridLayoutManager.VERTICAL);        rlv.setLayoutManager(mar);        //创建数据源        for (int i = 0; i <20; i++) {            data.add("条目"+i);        }        //设置适配器        MyAdapter adapter=new MyAdapter();        rlv.setAdapter(adapter);    }    class  MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder>{        //RecyclerView显示的子View        //该方法返回是ViewHolder，当有可复用View时，就不再调用        @Override        public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {            View v= View.inflate(MainActivity.this,R.layout.item,null);            return new ViewHolder(v);        }        //将数据绑定到子View，会自动复用View        @Override        public void onBindViewHolder(MyAdapter.ViewHolder holder, int position) {           holder.tv.setText(data.get(position));            LinearLayout.LayoutParams lp=new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT,100+(int)(Math.random()*50));            holder.iv.setLayoutParams(lp);        }        //RecyclerView显示数据条数        @Override        public int getItemCount() {            return data.size();        }        //自定义的ViewHolder,减少findViewById调用次数         class ViewHolder extends  RecyclerView.ViewHolder{                ImageView iv;                TextView tv;            //在布局中找到所含有的UI组件             public ViewHolder(View itemView) {                 super(itemView);                 tv=itemView.findViewById(R.id.textView);                 iv=itemView.findViewById(R.id.imageView);             }         }    }}