RecyclerView-Grid-with-Load-More

Elements.java

/**
 * Created by Vipul on 18/11/16.
 */

public class Elements {

    private int icon;
    private String name;

    public int getIcon() {
        return icon;
    }

    public void setIcon(int icon) {
        this.icon = icon;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

ElementsAdapter.java

import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import java.util.List;

/**
 * Created by Vipul on 18/11/16.
 */

public class ElementsAdapter extends RecyclerView.Adapter {

    interface Callbacks {
        public void onClickLoadMore();
    }

    private Callbacks mCallbacks;
    private static final int TYPE_HEADER = 0;
    private static final int TYPE_ITEM = 1;
    private static final int TYPE_FOOTER = 2;

    private boolean mWithHeader = false;
    private boolean mWithFooter = false;
    private List<Elements> mFeedList;

    public ElementsAdapter(List<Elements> feedList) {
        this.mFeedList = feedList;
    }

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

        View itemView = null;

        if (viewType == TYPE_FOOTER) {

            itemView = View.inflate(parent.getContext(), R.layout.row_loadmore, null);
            return new LoadMoreViewHolder(itemView);

        } else {

            itemView = View.inflate(parent.getContext(), R.layout.row_element, null);
            return new ElementsViewHolder(itemView);
        }
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {

        if(holder instanceof LoadMoreViewHolder) {

            LoadMoreViewHolder loadMoreViewHolder = (LoadMoreViewHolder) holder;

            loadMoreViewHolder.itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    if(mCallbacks!=null)
                        mCallbacks.onClickLoadMore();
                }
            });

        } else {
            ElementsViewHolder elementsViewHolder = (ElementsViewHolder) holder;

            Elements elements = mFeedList.get(position);
            elementsViewHolder.icon.setImageResource(elements.getIcon());
            elementsViewHolder.name.setText(elements.getName());
        }

    }

    @Override
    public int getItemCount() {
        int itemCount = mFeedList.size();
        if (mWithHeader)
            itemCount++;
        if (mWithFooter)
            itemCount++;
        return itemCount;
    }

    @Override
    public int getItemViewType(int position) {
        if (mWithHeader && isPositionHeader(position))
            return TYPE_HEADER;
        if (mWithFooter && isPositionFooter(position))
            return TYPE_FOOTER;
        return TYPE_ITEM;
    }

    public boolean isPositionHeader(int position) {
        return position == 0 && mWithHeader;
    }

    public boolean isPositionFooter(int position) {
        return position == getItemCount() - 1 && mWithFooter;
    }

    public void setWithHeader(boolean value){
        mWithHeader = value;
    }

    public void setWithFooter(boolean value){
        mWithFooter = value;
    }

    public void setCallback(Callbacks callbacks){
        mCallbacks = callbacks;
    }

    public class ElementsViewHolder extends RecyclerView.ViewHolder {

        private ImageView icon;
        private TextView name;

        public ElementsViewHolder(View itemView) {
            super(itemView);
            icon = (ImageView) itemView.findViewById(R.id.icon);
            name = (TextView) itemView.findViewById(R.id.name);
        }
    }

    public class LoadMoreViewHolder  extends RecyclerView.ViewHolder {

        public LoadMoreViewHolder(View itemView) {
            super(itemView);
        }
    }
}

GridDividerDecoration.java

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.v7.widget.RecyclerView;
import android.view.View;

/**
 * ItemDecoration implementation that applies and inset margin
 * around each child of the RecyclerView. It also draws item dividers
 * that are expected from a vertical list implementation, such as
 * ListView.
 */
public class GridDividerDecoration extends RecyclerView.ItemDecoration {

    private static final int[] ATTRS = { android.R.attr.listDivider };

    private Drawable mDivider;
    private int mInsets;

    public GridDividerDecoration(Context context) {
        TypedArray a = context.obtainStyledAttributes(ATTRS);
        mDivider = a.getDrawable(0);
        a.recycle();

        mInsets = 1;
    }

    @Override
    public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {
        drawVertical(c, parent);
        drawHorizontal(c, parent);
    }

    /** Draw dividers at each expected grid interval */
    public void drawVertical(Canvas c, RecyclerView parent) {
        if (parent.getChildCount() == 0) return;

        final int childCount = parent.getChildCount();

        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            final RecyclerView.LayoutParams params =
                    (RecyclerView.LayoutParams) child.getLayoutParams();

            final int left = child.getLeft() - params.leftMargin - mInsets;
            final int right = child.getRight() + params.rightMargin + mInsets;
            final int top = child.getBottom() + params.bottomMargin + mInsets;
            final int bottom = top + mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    /** Draw dividers to the right of each child view */
    public void drawHorizontal(Canvas c, RecyclerView parent) {
        final int childCount = parent.getChildCount();

        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            final RecyclerView.LayoutParams params =
                    (RecyclerView.LayoutParams) child.getLayoutParams();

            final int left = child.getRight() + params.rightMargin + mInsets;
            final int right = left + mDivider.getIntrinsicWidth();
            final int top = child.getTop() - params.topMargin - mInsets;
            final int bottom = child.getBottom() + params.bottomMargin + mInsets;
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        //We can supply forced insets for each item view here in the Rect
        outRect.set(mInsets, mInsets, mInsets, mInsets);
    }
}

MainActivity.java

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;

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

public class MainActivity extends AppCompatActivity implements ElementsAdapter.Callbacks{

    private List<Elements> mainList = new ArrayList<>();
    private List<Elements> dummyList = new ArrayList<>();
    private RecyclerView recyclerView;
    private ElementsAdapter elementsAdapter;

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

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

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

        int columns = 2;
        final GridLayoutManager gridLayoutManager = new GridLayoutManager(this, columns);

        recyclerView.addItemDecoration(new GridDividerDecoration(this));
        recyclerView.setLayoutManager(gridLayoutManager);

        gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
            @Override
            public int getSpanSize(int position) {
                return elementsAdapter.isPositionFooter(position) ? gridLayoutManager.getSpanCount() : 1;
            }
        });

        // added all elements to main list
        for(int i = 0; i<12; ++i) {
            Elements elements = new Elements();
            elements.setIcon(R.mipmap.ic_launcher);
            elements.setName("Element "+i);

            mainList.add(elements);
        }

        // now only add number of elements for the first show i.e. 6
        for(int i = 0; i<6; ++i) {
            dummyList.add(mainList.get(i));
        }

        elementsAdapter = new ElementsAdapter(dummyList);
        elementsAdapter.setCallback(this);
        elementsAdapter.setWithFooter(true); //enabling footer to show
        recyclerView.setAdapter(elementsAdapter);

    }

    @Override
    public void onClickLoadMore() {
        elementsAdapter.setWithFooter(false); // hide footer

        // now add remaining elements
        for(int i = 6; i<mainList.size(); ++i) {
            dummyList.add(mainList.get(i));
        }

        elementsAdapter.notifyDataSetChanged(); // more elements will be added
    }
}

row_element.xml

<?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="wrap_content"
    android:padding="25dp"
    android:background="@android:color/white"
    android:gravity="center">

    <ImageView
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:id="@+id/icon"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:id="@+id/name" />

</LinearLayout>

row_loadmore.xml

<?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="wrap_content"
    android:background="@android:color/white"
    android:gravity="center">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:padding="15dp"
        android:text="Load More"
        android:textSize="16sp"
        android:textColor="#FF5722"/>

</LinearLayout>