void addColumns(boolean addSize, boolean addDate) {
		if (!showSize && addSize) {
			this.addColumn("Size");
			this.showSize = true;

		}
		if (!showDate && addDate) {
			this.addColumn("Date");
			this.showDate = true;
		}

		if (showSize && !addSize) {
			this.showSize = false;
			this.columnIdentifiers.remove(this.findColumn("Size"));
		}
		if (showDate && !addDate) {
			this.showDate = false;
			this.columnIdentifiers.remove(this.findColumn("Date"));

		}

		fireTableStructureChanged();
		changeTableData();

	}