http://hi.baidu.com/suofang/blog/item/76cbd962be93f4dae7113ad2.html
public class ListSort {
public static void main(String args[]){ List list=new ArrayList(); Category c=new Category(); c.setCategoryName("服务展示"); c.setCategoryId(1); c.setParId(0); list.add(c); c=new Category(); c.setCategoryId(2); c.setCategoryName("用户注册"); c.setParId(0); list.add(c); c=new Category(); c.setCategoryId(3); c.setCategoryName("劳动就业"); //二级目录 c.setParId(1); list.add(c); c=new Category(); c.setCategoryId(4); c.setCategoryName("少儿保险"); c.setParId(1); list.add(c); c=new Category(); c.setCategoryId(5); c.setCategoryName("信息发布"); c.setParId(0); list.add(c); c=new Category(); c.setCategoryId(7); c.setCategoryName("新闻中心"); c.setParId(5); list.add(c); c=new Category(); c.setCategoryId(8); c.setCategoryName("养老保险"); c.setParId(1); list.add(c); /*c=new Category(); c.setCategoryId(6); c.setCategoryName("招工信息");//三级目录 c.setParId(3); list.add(c);*/ CategoryComparator cc=new ListSort().new CategoryComparator(); Collections.sort(list,cc); // 排序 Collections.reverse(list); for(Object o:list){ Category ca=(Category)o; System.out.println(ca.getParId()+"------"+ca.getCategoryName()); } } private class CategoryComparator implements Comparator{ //实现排序算法
public int compare(Object o1, Object o2) { Category c1=(Category)o1; Category c2=(Category)o2; if(c1.getParId()==c2.getParId()){ return 0; } else if(c1.getParId()>c2.getParId()){ return c1.getParId(); } return c2.getParId(); //实现了二级目录，三级目录就不行了 }}}
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public class ListSort { List sortList=new ArrayList(); //用递归会增加一培的内存 static List list=new ArrayList(); public static void main(String args[]){ ListSort ls=new ListSort(); Category c=new Category(); c.setCategoryName("服务展示"); c.setCategoryId(1); c.setParId(0); list.add(c); c=new Category(); c.setCategoryId(2); c.setCategoryName("用户注册"); c.setParId(0); list.add(c); c=new Category(); c.setCategoryId(3); c.setCategoryName("劳动就业"); //二级目录 c.setParId(1); list.add(c); c=new Category(); c.setCategoryId(4); c.setCategoryName("少儿保险"); c.setParId(1); list.add(c); c=new Category(); c.setCategoryId(5); c.setCategoryName("信息发布"); c.setParId(0); list.add(c); c=new Category(); c.setCategoryId(7); c.setCategoryName("新闻中心"); c.setParId(5); list.add(c); c=new Category(); c.setCategoryId(8); c.setCategoryName("养老保险"); c.setParId(1); list.add(c); c=new Category(); c.setCategoryId(6); c.setCategoryName("招工信息");//三级目录 c.setParId(3); list.add(c);
ls.tree(0); for(Object o:ls.sortList){ Category cc=(Category)o; System.out.println("id: "+cc.getCategoryId()+" par: "+cc.getParId()+" name: "+cc.getCategoryName()); } }
public void tree(int n){ int size=list.size(); for(int i=0;i<size;i++){ Category c=(Category)list.get(i); if(c.getParId()==n){ sortList.add(c); tree(c.getCategoryId()); //自调用，递归 } } }}
显示如下
id: 1 par: 0 name: 服务展示id: 3 par: 1 name: 劳动就业id: 6 par: 3 name: 招工信息id: 4 par: 1 name: 少儿保险id: 8 par: 1 name: 养老保险id: 2 par: 0 name: 用户注册id: 5 par: 0 name: 信息发布id: 7 par: 5 name: 新闻中心
相关资源：java的arraylist排序示例(arraylist用法)
