Android Studio – Android Studio Recycler View have gaps between the rows. Help me fix

I followed this tutorial on youtube for my school project. The app is able to display selected images from gallery but the recycler view have gaps in every row. What do I code to fix this app? help. enter image description here

here’s my activity_main.xml

<?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"
    android:scrollbarStyle="insideInset"
    android:scrollbars="vertical"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/pick"
        android:layout_width="53dp"
        android:layout_height="64dp"
        android:layout_margin="12dp"
        android:layout_weight="0"
        android:backgroundTint="#FF5722"
        android:text="+"
        android:textSize="24sp"
        app:cornerRadius="64dp" />

    <TextView
        android:id="@+id/totalPhotos"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_weight="0"
        android:gravity="center"
        android:textColor="#FFFFFF" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView_Gallery_Images"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="5dp"
        android:layout_weight="1"


</LinearLayout>

RecyclerAdapter.java

package com.example.mygram;

import android.media.Image;
import android.net.Uri;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;

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

import java.util.ArrayList;

public class RecyclerAdapter extends RecyclerView.Adapter<RecyclerAdapter.ViewHolder> {

    private ArrayList<Uri> uriArrayList;

    public RecyclerAdapter(ArrayList<Uri> uriArrayList) {
        this.uriArrayList = uriArrayList;
    }

    @NonNull
    @Override
    public RecyclerAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

        LayoutInflater inflater = LayoutInflater.from(parent.getContext());
        View view = inflater.inflate(R.layout.custom_single_image,parent, false);

        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerAdapter.ViewHolder holder, int position) {
        holder.imageView.setImageURI(uriArrayList.get(position));

    }

    @Override
    public int getItemCount() {

        return uriArrayList.size();
    }

    public class ViewHolder extends RecyclerView.ViewHolder {

        ImageView imageView;
        public ViewHolder(@NonNull View itemView) {
            super(itemView);

            imageView = itemView.findViewById(R.id.image);
        }
    }
}

Custom single images.xml

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

    <ImageView
        android:id="@+id/image"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:scaleType="centerCrop"
        app:layout_constraintDimensionRatio="1"
        tools:ignore="MissingConstraints" />

</androidx.constraintlayout.widget.ConstraintLayout>

And here’s the MainActivity.java

package com.example.mygram;

import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import androidx.recyclerview.widget.GridLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.Manifest;
import android.app.Activity;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {
    RecyclerView recyclerView;
    TextView textView;
    Button pick;

    ArrayList <Uri> uri = new ArrayList<>();
    RecyclerAdapter adapter ;

    private static final int Read_Permission = 101;

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

        textView = findViewById(R.id.totalPhotos);
        recyclerView = findViewById(R.id.recyclerView_Gallery_Images);
        pick = findViewById(R.id.pick);

        adapter = new RecyclerAdapter(uri);
        recyclerView.setLayoutManager(new GridLayoutManager(MainActivity.this,3));
        recyclerView.setAdapter(adapter);

        if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {

            ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, Read_Permission);
        }


        pick.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent();
                intent.setType("image/*");
                if  (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR2){
                    intent.putExtra(Intent.EXTRA_ALLOW_MULTIPLE, true);
                }
                intent.setAction(Intent.ACTION_GET_CONTENT);
                startActivityForResult(Intent.createChooser(intent, "Select Picture"), 1);
            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if(requestCode == 1 && resultCode == Activity.RESULT_OK){
            if(data.getClipData() !=null) {
                int x = data.getClipData().getItemCount();

                for (int i = 0; i < x; i++) {
                    uri.add(data.getClipData().getItemAt(i).getUri());
                }

                adapter.notifyDataSetChanged();
                textView.setText("Photos ("+uri.size()+")");
            }else if (data.getData()!=null){
                String imageURL=data.getData().getPath();
                uri.add(Uri.parse(imageURL));
            }
        }
    }
}

The concept of the app is instagram feed tester. I want to be able to display images like the grid in instagram but the gap is appearing preventing it to happen. help me please thankyou