Getting a NullPointerException when I click the 7 Day button

    holder.dayLabel.setText(day.getDayOfTheWeek());
    holder.iconImageView.setImageResource(day.getIconId());

private Context mContext;
private Day[] mDays;

public DayAdapter(Context context, Day[] days)
{
    mContext = context;
    mDays = days;
}

@Override
public int getCount() {
    return mDays.length;
}

@Override
public Object getItem(int position) {
    return mDays[position];
}

@Override
public long getItemId(int position) {
    return 0; // We aren't going to use this. Tag items for easy reference
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {

    ViewHolder holder;



    if (convertView == null)
    {
        // Brand new
        convertView = LayoutInflater.from(mContext).inflate(R.layout.daily_list_item, null);
        holder = new ViewHolder();
        holder.iconImageView = (ImageView) convertView.findViewById(R.id.iconImageView);
        holder.temperatureLabel = (TextView) convertView.findViewById(R.id.temperatureLabel);
        holder.dayLabel = (TextView) convertView.findViewById(R.id.dayNameLabel);

        convertView.setTag(holder);
    }
    else
    {
        holder = (ViewHolder) convertView.getTag();
    }

    Day day = mDays[position];


    holder.temperatureLabel.setText(day.getTemperatureMax() + "");
    holder.dayLabel.setText(day.getDayOfTheWeek());
    holder.iconImageView.setImageResource(day.getIconId());



    return convertView;
}

private static class ViewHolder
{
    ImageView iconImageView;
    TextView temperatureLabel;
    TextView dayLabel;
}

public long getTime() {
    return mTime;
}

public void setTime(long time) {
    mTime = time;
}

public String getSummary() {
    return mSummary;
}

public void setSummary(String summary) {
    mSummary = summary;
}

public int getTemperatureMax()
{
    return (int) Math.round(mTemperatureMax);

}

public void setTemperatureMax(double temperatureMax) {
    mTemperatureMax = temperatureMax;
}

public String getIcon() {
    return mIcon;
}

public void setIcon(String icon) {
    mIcon = icon;
}

public String getTimezone() {
    return mTimezone;
}

public void setTimezone(String timezone) {
    mTimezone = timezone;
}

public int getIconId()
{
    return Forecast.getIconId(mIcon);
}

public String getDayOfTheWeek()
{
    SimpleDateFormat formatter = new SimpleDateFormat("EEEE");
    formatter.setTimeZone(TimeZone.getTimeZone(mTimezone));

    Date dateTime = new Date(mTime * 1000);

    return formatter.format(dateTime);
}

@Override
public int describeContents() {
    return 0;
}

@Override
public void writeToParcel(Parcel dest, int flags)
{
    dest.writeLong(mTime);
    dest.writeString(mSummary);
    dest.writeDouble(mTemperatureMax);
    dest.writeString(mIcon);
    dest.writeString(mTimezone);
}

private Day(Parcel in)
{
    mTime = in.readLong();
    mSummary = in.readString();
    mTemperatureMax = in.readDouble();
    mIcon = in.readString();
    mTimezone = in.readString();

}

public Day() {}

public static final Creator<Day> CREATOR = new Creator<Day>() {
    @Override
    public Day createFromParcel(Parcel source) {
        return new Day(source);
    }

    @Override
    public Day[] newArray(int size) {
        return new Day[size];
    }
};