ArrayListはフィールドごとに並べ替えられます

public class CategoryLevel
{
	private Integer categoryId;
    private String categoryName;
    private List<OptionLevel> categoryItem = new ArrayList<OptionLevel>();
    
    public Integer getCategoryId() 
    {
		return categoryId;
	}
	public void setCategoryId(Integer categoryId) 
	{
		this.categoryId = categoryId;
	}
	public String getCategoryName() 
	{
		return categoryName;
	}
	public void setCategoryName(String categoryName) 
	{
		this.categoryName = categoryName;
	}
	public List<OptionLevel> getCategoryItem() 
	{
		return categoryItem;
	}
	public void setCategoryItem(List<OptionLevel> categoryItem) 
	{
		this.categoryItem = categoryItem;
	}


}

List<CategoryLevel> list = new ArrayList<CategoryLevel>();
list.add();
.....
Collections.sort(list, new Comparator<CategoryLevel>() {
    		   	            public int compare(CategoryLevel arg0, CategoryLevel arg1) {
    		   	                return arg0.getCategoryName().compareTo(arg1.getCategoryName());
    		   	            }
    		   	        });