[Android开发] RecyleView+Checkbox 实现勾选条目删除简单功能 + 删除完后用图片占位

戴墨镜的非洲猴子先生

已于 2024-11-16 17:14:12 修改

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分类专栏： Android技术分享文章标签： android

于 2024-08-28 22:04:33 首次发布

本文链接：https://blog.youkuaiyun.com/studyForMokey/article/details/141651111

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文章目录

0. 技术点：Recyleview的删除事件，比较简单
1. activity + adpter
2. item.xml
3. 占位
- 3.1 xml
- 3.2 activity

0. 技术点：Recyleview的删除事件，比较简单

1. activity + adpter

package com.example.myapplication.view;

import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.TextView;

import com.example.myapplication.R;

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

public class ForthActivity extends AppCompatActivity {

    private RecyclerView recyclerView;
    private Button btnDelete;
    private MyAdapter adapter;

    private List<String> data = new ArrayList<>();

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

        // 初始化数据
        for (int i = 1; i <= 5; i++) {
            data.add("Item " + i);
        }

        recyclerView = findViewById(R.id.recyclerView);
        btnDelete = findViewById(R.id.btnDelete);

        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        adapter = new MyAdapter(data);
        recyclerView.setAdapter(adapter);

        btnDelete.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                adapter.deleteSelectedItems();
            }
        });
    }
// 核心
    private class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {

        private List<String> data;
        private List<Boolean> checkedItems;

        public MyAdapter(List<String> data) {
            this.data = data;
            this.checkedItems = new ArrayList<>(data.size());
            for (int i = 0; i < data.size(); i++) {
                checkedItems.add(false);
            }
        }

        @Override
        public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_layout, parent, false);
            return new MyViewHolder(view);
        }

        @Override
        public void onBindViewHolder(MyViewHolder holder, int position) {
            holder.textView.setText(data.get(position));
            holder.checkbox.setChecked(checkedItems.get(position)); // 核心
			// 核心
            // 设置监听器前先移除当前的，否则会重复绑定
            holder.checkbox.setOnCheckedChangeListener(null);
            holder.checkbox.setOnCheckedChangeListener((buttonView, isChecked) -> {
                checkedItems.set(position, isChecked);
            });
        }

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

        public void deleteSelectedItems() {
            for (int i = data.size() - 1; i >= 0; i--) {
                if (checkedItems.get(i)) {
                    data.remove(i);
                    checkedItems.remove(i);// 核心
                    notifyItemRemoved(i); // 核心
                    notifyDataSetChanged(); // 核心

                }
            }
        }

        class MyViewHolder extends RecyclerView.ViewHolder {
            CheckBox checkbox;
            TextView textView;

            MyViewHolder(View itemView) {
                super(itemView);
                checkbox = itemView.findViewById(R.id.checkbox);
                textView = itemView.findViewById(R.id.textView);
            }
        }
    }
}

2. item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal">

    <CheckBox
        android:id="@+id/checkbox"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp" />

</LinearLayout>

3. 占位

3.1 xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:id="@+id/btnDelete"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Delete Selected Items"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@id/btnDelete" />
    <ImageView
        android:id="@+id/placeholderImageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:src="@drawable/ic_launcher_background"
        android:visibility="gone"/>
</RelativeLayout>

3.2 activity

package com.example.myapplication.view;

import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.ImageView;
import android.widget.TextView;

import com.example.myapplication.R;

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

public class ForthActivity extends AppCompatActivity {

    private RecyclerView recyclerView;
    private Button btnDelete;
    private MyAdapter adapter;

    private List<String> data = new ArrayList<>();

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

        // 初始化数据
        for (int i = 1; i <= 5; i++) {
            data.add("Item " + i);
        }

        recyclerView = findViewById(R.id.recyclerView);
        btnDelete = findViewById(R.id.btnDelete);

        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        adapter = new MyAdapter(data);
        recyclerView.setAdapter(adapter);
        ImageView placeholderImageView = findViewById(R.id.placeholderImageView);

        btnDelete.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                adapter.deleteSelectedItems();
                if (adapter.getItemCount() == 0) {
                    recyclerView.setVisibility(View.GONE);
                    placeholderImageView.setVisibility(View.VISIBLE);
                } else {
                    recyclerView.setVisibility(View.VISIBLE);
                    placeholderImageView.setVisibility(View.GONE);
                }
            }

        });


    }

    private class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {

        private List<String> data;
        private List<Boolean> checkedItems;

        public MyAdapter(List<String> data) {
            this.data = data;
            this.checkedItems = new ArrayList<>(data.size());
            for (int i = 0; i < data.size(); i++) {
                checkedItems.add(false);
            }
        }

        @Override
        public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_layout, parent, false);
            return new MyViewHolder(view);
        }

        @Override
        public void onBindViewHolder(MyViewHolder holder, int position) {
            holder.textView.setText(data.get(position));
            holder.checkbox.setChecked(checkedItems.get(position));

            // 设置监听器前先移除当前的，否则会重复绑定
            holder.checkbox.setOnCheckedChangeListener(null);
            holder.checkbox.setOnCheckedChangeListener((buttonView, isChecked) -> {
                checkedItems.set(position, isChecked);
            });
        }

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

        public void deleteSelectedItems() {
            for (int i = data.size() - 1; i >= 0; i--) {
                if (checkedItems.get(i)) {
                    data.remove(i);
                    checkedItems.remove(i);
                    notifyItemRemoved(i);
                    notifyDataSetChanged();

                }
            }
        }

        class MyViewHolder extends RecyclerView.ViewHolder {
            CheckBox checkbox;
            TextView textView;

            MyViewHolder(View itemView) {
                super(itemView);
                checkbox = itemView.findViewById(R.id.checkbox);
                textView = itemView.findViewById(R.id.textView);
            }
        }
    }
}