HashSet实现多选

HashSet 实现多选，先看效果图：

这是HashMap实现单选和HashSet实现多选的下载链接

下面是主要内容：

• MainActivity 主要代码以及 activity_main 布局文件代码
• MoreAdapter 主要代码以及 adapter_more 布局文件代码

1. MainActivity 主要代码以及 activity_main 布局文件代码

MainActivity 主要代码：

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

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;

/**
 * author: wu
 * date: on 2018/11/12.
 * describe:多选主 Activity
 */
public class MainActivity extends AppCompatActivity {
    private List<String> list;
    private RecyclerView rv_more;
    private HashSet<Integer> hashSet = new HashSet<>();

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

        //列表中添加数据
        setList();
        //设置多选适配器
        setMore();
    }

    private void setList() {
        list = new ArrayList<>();
        list.add("英雄联盟");
        list.add("王者荣耀");
        list.add("刺激战场");
        list.add("绝地求生");
        list.add("第五人格");
        list.add("唱歌");
        list.add("聊天");
        list.add("全军出击");
    }

    private void setMore() {
        rv_more = findViewById(R.id.rv_more);
        MoreAdapter adapter = new MoreAdapter(this, list);
        rv_more.setAdapter(adapter);
        rv_more.setLayoutManager(new GridLayoutManager(this, 3));
        //adapter中item点击事件
        adapter.setOnItemClickListerer(new MoreAdapter.OnItemClickListener() {
            @Override
            public void onItemClick(int position, HashSet<Integer> set) {
                hashSet = set;
                Toast.makeText(MainActivity.this, setName(), Toast.LENGTH_SHORT).show();
            }
        });
    }

    //把列表用逗号隔开
    private String setName() {
        String listStr = "";
        for (Integer position : hashSet) {
            if (listStr.equals("")) {
                listStr = list.get(position);
            } else {
                listStr = listStr + "," + list.get(position);
            }
        }
        return listStr;
    }
}

activity_main 布局文件代码：

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

    <TextView
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:background="@color/colorPrimary"
        android:gravity="center"
        android:text="HashSet实现多选" />

    <android.support.v7.widget.RecyclerView
        android:id="@+id/rv_more"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

2. MoreAdapter 主要代码以及 adapter_more 布局文件代码

MoreAdapter 主要代码：

/**
 * author: wu
 * date: on 2018/11/12.
 * describe:多选适配器
 */

public class MoreAdapter extends RecyclerView.Adapter<MoreAdapter.MyViewHolder> {
    private final LayoutInflater mInflater;
    private Context context;
    private List<String> list;
    private HashSet<Integer> hashSet = new HashSet();

    public MoreAdapter(Context mContext, List<String> list) {
        this.context = mContext;
        this.list = list;
        mInflater = LayoutInflater.from(context);
    }

    //接口回调
    public interface OnItemClickListener {
        void onItemClick(int position, HashSet<Integer> hashSet);
    }

    public MoreAdapter.OnItemClickListener mOnItemClickListerer;

    public void setOnItemClickListerer(MoreAdapter.OnItemClickListener listerer) {
        this.mOnItemClickListerer = listerer;
    }

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = mInflater.inflate(R.layout.adapter_one, parent, false);
        MyViewHolder viewHolder = new MyViewHolder(view);
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(final MyViewHolder holder, final int position) {
        holder.tv_name.setText(list.get(position));//设置显示名称
        //item点击事件
        holder.itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                addOrRemove(position,holder);
                //点击回调
                mOnItemClickListerer.onItemClick(position, hashSet);
            }
        });
    }

    //操作Item记录集合
    private void addOrRemove(int position, MyViewHolder holder) {
        if (hashSet.contains(position)) {
            // 如果包含，则撤销选择
            hashSet.remove(position);
            holder.tv_check.setVisibility(View.GONE);
            holder.tv_name.setTextColor(Color.parseColor("#FF666666"));
        } else {
            // 如果不包含，则添加
            hashSet.add(position);
            holder.tv_check.setVisibility(View.VISIBLE);
            holder.tv_name.setTextColor(Color.parseColor("#FF3300"));
        }
    }

    @Override
    public int getItemCount() {
        return list != null ? list.size() : 0;
    }

    class MyViewHolder extends RecyclerView.ViewHolder {
        TextView tv_check, tv_name;

        public MyViewHolder(View itemView) {
            super(itemView);
            tv_name = itemView.findViewById(R.id.tv_name);
            tv_check = itemView.findViewById(R.id.tv_check);
        }
    }
}

adapter_more 布局文件代码 ：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="35dp"
    android:layout_margin="10dp"
    android:layout_weight="1"
    android:gravity="center"
    android:orientation="horizontal"
    android:background="#FFEEEEEE">

    <TextView
        android:id="@+id/tv_check"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="√"
        android:textColor="#FF3300"
        android:textSize="12sp"
        android:visibility="gone"/>

    <TextView
        android:id="@+id/tv_name"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_marginLeft="2dp"
        android:gravity="center"
        android:text="不限"
        android:textColor="#FF666666"
        android:textSize="12sp" />
</LinearLayout>

这样便可以用 HashSet 实现单选。