[RecyclerView] RecyclerView basic usage (add support libraries | set the layout file | custom adapter)

I. Adding support library

---

Configuration dependent RecyclerView library dependencies Module in the build.gradle;

dependencies {
    implementation "androidx.recyclerview:recyclerview:1.1.0"
}

II. Layout file using RecyclerView

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

	<!-- 设置列表 -->
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recycler_view"
        android:scrollbars="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</androidx.constraintlayout.widget.ConstraintLayout>

III. Custom adapter

    /**
     * RecyclerView 适配器
     */
    public class Adapter extends RecyclerView.Adapter<Adapter.ViewHolder> {

        /**
         * 初始化布局文件
         * @param parent
         * @param viewType
         * @return
         */
        @NonNull
        @Override
        public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
            View root_view = LayoutInflater.from(MainActivity.this)
            	.inflate(R.layout.item_recyclerview, parent, false);
            return new ViewHolder(root_view);
        }

        /**
         * 设置每个列表项的显示内容
         * @param holder
         * @param position
         */
        @Override
        public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
            holder.text.setText("" + position);
        }

        /**
         * 获取列表项个数
         * @return
         */
        @Override
        public int getItemCount() {
            return 10;
        }

        /**
         * 布局容器
         */
        public class ViewHolder extends RecyclerView.ViewHolder {
            TextView text;

            public ViewHolder(@NonNull View itemView) {
                super(itemView);
                text = itemView.findViewById(R.id.text);
            }
        }

    }

IV. RecyclerView setup process

RecyclerView setup process:

① initialization RecyclerView objects: usually obtained from the layout file;

② create and set Layout Manager: You can use preset layout manager, you can also customize the layout manager;

③ adapter set: usually custom adapter is provided to RecyclerView objects;

//1 . 从布局中获取 RecyclerView
RecyclerView recycler_view = findViewById(R.id.recycler_view);

//2 . 创建并设置布局管理器
//创建布局管理器
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
layoutManager.setOrientation(RecyclerView.VERTICAL);
//设置布局管理器
recycler_view.setLayoutManager(layoutManager);

//3 . 创建并设置列表适配器
Adapter adapter = new Adapter();
recycler_view.setAdapter(adapter);

V. RecyclerView complete Java code example

package kim.hsl.recyclerview;

import androidx.annotation.NonNull;
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.TextView;

public class MainActivity extends AppCompatActivity {



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

        //1 . 从布局中获取 RecyclerView
        RecyclerView recycler_view = findViewById(R.id.recycler_view);


        //2 . 创建并设置布局管理器
        //创建布局管理器
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        layoutManager.setOrientation(RecyclerView.VERTICAL);

        //设置布局管理器
        recycler_view.setLayoutManager(layoutManager);


        //3 . 创建并设置列表适配器
        Adapter adapter = new Adapter();
        recycler_view.setAdapter(adapter);
    }


    /**
     * RecyclerView 适配器
     */
    public class Adapter extends RecyclerView.Adapter<Adapter.ViewHolder> {

        /**
         * 初始化布局文件
         * @param parent
         * @param viewType
         * @return
         */
        @NonNull
        @Override
        public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
            View root_view = LayoutInflater.from(MainActivity.this)
            	.inflate(R.layout.item_recyclerview, parent, false);
            return new ViewHolder(root_view);
        }

        /**
         * 设置每个列表项的显示内容
         * @param holder
         * @param position
         */
        @Override
        public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
            holder.text.setText("" + position);
        }

        /**
         * 获取列表项个数
         * @return
         */
        @Override
        public int getItemCount() {
            return 10;
        }

        /**
         * 布局容器
         */
        public class ViewHolder extends RecyclerView.ViewHolder {
            TextView text;

            public ViewHolder(@NonNull View itemView) {
                super(itemView);
                text = itemView.findViewById(R.id.text);
            }
        }

    }

}

Code Address: https://github.com/han1202012/001_RecyclerView