Recyclerview to busy and crashes

I often get the error "Cannot call this method while RecyclerView is computing a layout or scrolling". I think this is caused by having 5 fragments creating an recyclerview at the same time. I could fix it by setting the viewPager.setOffscreenPageLimit to 2, but that is not quitte the solution as I'm using threads and can't afford to get an tab out of focus.

I was think about adding fragments, with a slight time delay, but failed to do so. Anyone knows how to fix it?

Solution, but not optimal for me due to threads: viewPager.setOffscreenPageLimit(2);

My onload and public class:

Public class MainActivity {
    static MainActivity main;
    Toolbar toolbar;
    TabLayout tabLayout;
    ViewPager viewPager;
    ViewPagerAdapter viewPagerAdapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    toolbar = (Toolbar) findViewById(R.id.toolBar);
    setSupportActionBar(toolbar);
    tabLayout = (TabLayout) findViewById(R.id.tabLayout);
    viewPager = (ViewPager) findViewById(R.id.viewPager);
    viewPagerAdapter = new ViewPagerAdapter(getSupportFragmentManager());
    viewPagerAdapter.addFragments(new Maandag_home(), "MA");
    viewPagerAdapter.addFragments(new Dinsdag_home(), "DI");
    viewPagerAdapter.addFragments(new Woensdag_home(), "WO");
    viewPagerAdapter.addFragments(new Donderdag_home(), "DO");
    viewPagerAdapter.addFragments(new Vrijdag_home(), "VR");
    viewPager.setAdapter(viewPagerAdapter);
    tabLayout.setupWithViewPager(viewPager);
}

Viewpager adapter code:

package com.mycompany.myapp;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;

import java.util.ArrayList;

public class ViewPagerAdapter extends FragmentPagerAdapter {

ArrayList<Fragment> fragments = new ArrayList<>();
ArrayList<String> tabTitles = new ArrayList<>();

public void addFragments(Fragment fragments, String titles)
{
    this.fragments.add(fragments);
    this.tabTitles.add(titles);
}

public ViewPagerAdapter (FragmentManager fm)
{
    super(fm);
}
@Override
public Fragment getItem(int position) {
    return fragments.get(position);
}

@Override
public int getCount() {
    return fragments.size();
}

@Override
public CharSequence getPageTitle(int position) {
    return tabTitles.get(position);
}
}

Recyclerview adapter:

package com.mycompany.myapp;
import android.graphics.Color;
import android.support.v7.widget.CardView;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import java.util.ArrayList;

public class MyRecyclerViewAdapter extends RecyclerView
    .Adapter<MyRecyclerViewAdapter
    .DataObjectHolder> {
private static String LOG_TAG = "MyRecyclerViewAdapter";
private ArrayList<DataObject> mDataset;
private static MyClickListener myClickListener;

public static class DataObjectHolder extends RecyclerView.ViewHolder
        implements View
        .OnClickListener {
    TextView label;
    TextView dateTime;
    TextView tijd;
    CardView cardView;

    public DataObjectHolder(View itemView) {
        super(itemView);
        label = (TextView) itemView.findViewById(R.id.textView);
        dateTime = (TextView) itemView.findViewById(R.id.textView2);
        tijd = (TextView) itemView.findViewById(R.id.textView3);
        cardView = (CardView) itemView.findViewById(R.id.card_view);
        Log.i(LOG_TAG, "Adding Listener");
        itemView.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        myClickListener.onItemClick(getAdapterPosition(), v);
    }
}

public void setOnItemClickListener(MyClickListener myClickListener) {
    this.myClickListener = myClickListener;
}

public MyRecyclerViewAdapter(ArrayList<DataObject> myDataset) {
    mDataset = myDataset;
}

@Override
public DataObjectHolder onCreateViewHolder(ViewGroup parent,
                                           int viewType) {
    View view = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.card_view_row, parent, false);

    DataObjectHolder dataObjectHolder = new DataObjectHolder(view);
    return dataObjectHolder;
}

@Override
public void onBindViewHolder(DataObjectHolder holder, int position) {
    holder.label.setText(mDataset.get(position).getmText1());
    holder.dateTime.setText(mDataset.get(position).getmText2());
    holder.tijd.setText(mDataset.get(position).getmText3());
    String color = mDataset.get(position).getmState();
    if (color == "FFFFFF") {}
    else if (color == "F44336") {
        holder.cardView.setCardBackgroundColor(0xFFF44336);
        holder.label.setTextColor(0xFFFFFFFF);
        holder.dateTime.setTextColor(0xFFFFFFFF);
    }
    else if (color == "4CAF50"){
        holder.cardView.setCardBackgroundColor(0xFF4CAF50);
        holder.label.setTextColor(0xFFFFFFFF);
        holder.dateTime.setTextColor(0xFFFFFFFF);
    }
    else if (color == "FFEB3B") {
        holder.cardView.setCardBackgroundColor(0xFFFFEB3B);
    }
    else if (color == "607D8B") {
        holder.cardView.setCardBackgroundColor(0xFF607D8B);
    }
}

public void addItem(DataObject dataObj, int index) {
    mDataset.add(index, dataObj);
    notifyItemInserted(index);
}

public void deleteItem(int index) {
    mDataset.remove(index);
    notifyItemRemoved(index);
}

@Override
public int getItemCount() {
    return mDataset.size();
}

public interface MyClickListener {
    public void onItemClick(int position, View v);
}
}

How I add items (cards) to the recyclerview programatically:

DataObject obj = new DataObject("My Subject", "My Teacher", "Time", "FFFFFF");
((MyRecyclerViewAdapter) mAdapter).addItem(obj, index);

Error when running with viewPager.setOffscreenPageLimit(4)

FATAL EXCEPTION: Thread-7997 Process: com.mycompany.myapp, PID: 21990 java.lang.IllegalStateException: Cannot call this method while RecyclerView is computing a layout or scrolling at android.support.v7.widget.RecyclerView.assertNotInLayoutOrScroll(RecyclerView.java:2186) at android.support.v7.widget.RecyclerView$RecyclerViewDataObserver.onItemRangeInserted(RecyclerView.java:4281) at android.support.v7.widget.RecyclerView$AdapterDataObservable.notifyItemRangeInserted(RecyclerView.java:9969) at android.support.v7.widget.RecyclerView$Adapter.notifyItemInserted(RecyclerView.java:5856) at com.mycompany.myapp.MyRecyclerViewAdapter.addItem(MyRecyclerViewAdapter.java:89) at com.mycompany.myapp.Maandag_home$2.run(Maandag_home.java:174)

I think I've given enough information, if not please comment instead of immediately downvoting. I searched through the internet quitte a lot, even asked a Java developer, but he and the internet just didn't know.

PS: I'm wondering if the title is wrong, please correct it if it is