android RecyclerView的Grid布局案例

<?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=".GridActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/rv2"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:layout_editor_absoluteX="103dp"
        tools:layout_editor_absoluteY="44dp" />
</androidx.constraintlayout.widget.ConstraintLayout>

<?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="wrap_content"
    android:layout_height="wrap_content"
    tools:context=".GridItemActivity">

    <TextView
        android:id="@+id/textView3"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:text="@string/textview2"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

package com.example.myapplication;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

public class GridAdapter extends RecyclerView.Adapter<GridAdapter.GridViewHolder> {
    private Context context;
    public GridAdapter(Context context){
        this.context = context;
    }
    @NonNull
    @Override
    public GridAdapter.GridViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        return new GridViewHolder(LayoutInflater.from(context).inflate(R.layout.activity_grid_item,parent,false));
    }

    @Override
    public void onBindViewHolder(@NonNull GridAdapter.GridViewHolder holder, final int position) {
        holder.tv.setText("Hello world");

        holder.tv.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Toast.makeText(context,"click..."+position,Toast.LENGTH_SHORT).show();
            }
        });
    }

    @Override
    public int getItemCount() {
        return 30;
    }

    class GridViewHolder extends RecyclerView.ViewHolder{

        private TextView tv;
        public GridViewHolder(@NonNull View itemView) {
            super(itemView);
            tv = itemView.findViewById(R.id.textView3);
        }
    }
}

package com.example.myapplication;

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

import android.os.Bundle;

public class GridActivity extends AppCompatActivity {

    private RecyclerView rv;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_grid);

        rv = findViewById(R.id.rv2);

        rv.setLayoutManager(new GridLayoutManager(GridActivity.this,3));

        rv.setAdapter(new GridAdapter(GridActivity.this));
    }
}