Dynamically add a gridlayout

sample.java

package com.testapp;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.CardView;
import android.support.v7.widget.GridLayout;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.view.ViewGroup;
import android.widget.ImageView;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        ViewGroup root =  (ViewGroup) findViewById(R.id.content_main);
        addCustomView(root);
    }

    private void addCustomView(ViewGroup root) {
        GridLayout gridLayout = new GridLayout(this);
        GridLayout.LayoutParams layoutParams = new GridLayout.LayoutParams();
        layoutParams.height = GridLayout.LayoutParams.MATCH_PARENT;
        layoutParams.width = GridLayout.LayoutParams.MATCH_PARENT;
        layoutParams.setMargins(10, 10, 10, 10);
        gridLayout.setLayoutParams(layoutParams);

        gridLayout.setColumnCount(3);
        gridLayout.setRowCount(5);

        int[] arr = {3, 4, 3, 2};
        int r = 0, c = 0;
        for (int i=0; i<4; i++) {
            for(int j=0; j<arr[i]; j++) {
                CardView cardView  =  createChild();
                if( c == 3 ) {
                    c = 0;
                    r++;
                }

                ImageView imageView = new ImageView(this);
                imageView.setImageResource(R.mipmap.ic_launcher);
                imageView.setLayoutParams(new ViewGroup.LayoutParams(150, 150));

                GridLayout.Spec rowSpan = GridLayout.spec(GridLayout.UNDEFINED, 1, 1f);
                GridLayout.Spec colSpan = GridLayout.spec(GridLayout.UNDEFINED, 1, 1f);

//                if(r == 0 && c == 0) {
//                    colSpan = GridLayout.spec(GridLayout.UNDEFINED, 1);
//                    rowSpan = GridLayout.spec(GridLayout.UNDEFINED, 2);
//                }

                GridLayout.LayoutParams gridParam = new GridLayout.LayoutParams(
                        rowSpan, colSpan
                );
                cardView.addView(imageView);
                gridLayout.addView(cardView, gridParam);
                r++; c++;
            }

        }

        root.addView(gridLayout);

    }

    private CardView createChild() {
        CardView cardView = new CardView(this);
        cardView.setCardElevation(2);
        cardView.setUseCompatPadding(true);
        ViewGroup.LayoutParams cvLayoutParams = new ViewGroup.LayoutParams(
                ViewGroup.LayoutParams.WRAP_CONTENT,
                ViewGroup.LayoutParams.WRAP_CONTENT
        );
        cardView.setLayoutParams(cvLayoutParams);
        return cardView;
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}