1.GridView

gridview_item

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

    <ImageView
        android:id="@+id/img1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

</LinearLayout>

main

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:orientation="vertical"
    tools:context=".MainActivity">

   <GridView
       android:id="@+id/gridviewid"
       android:layout_width="match_parent"
       android:layout_height="match_parent"
       android:numColumns="4"
       android:horizontalSpacing="10dp"
       android:verticalSpacing="10dp"/>

</LinearLayout>

GridAdapter

package com.example.first;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;

import java.util.ArrayList;

public class GridAdapter extends BaseAdapter {

    Context context;
    ImageView imageView;

    public GridAdapter(Context context) {
        this.context = context;
    }

    //返回的是gridview的数量
    @Override
    public int getCount() {
        return 20;
    }

    @Override
    public Object getItem(int i) {
        return i;
    }

    @Override
    public long getItemId(int i) {
        return i;
    }

    //最重要的一个方法，给gridview加载数据
    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
        if (view == null){
            view = LayoutInflater.from(context).inflate(R.layout.gridview_item,viewGroup,false);
        }
        imageView = view.findViewById(R.id.img1);
        imageView.setImageResource(R.drawable.ic_android_black_24dp);
        return view;
    }
}

mainactivity

package com.example.first;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.os.PersistableBundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.GridLayout;
import android.widget.GridView;
import android.widget.ListView;
import android.widget.Toast;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    private GridView gridView;

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

        gridView = findViewById(R.id.gridviewid);
        gridView.setAdapter(new GridAdapter(this));

        gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                Toast.makeText(getApplicationContext(),"点击了："+i,Toast.LENGTH_SHORT).show();
            }
        });

    }
}