// 把一个List平均分成二个List
public static List[] splitList(List list) {
ArrayList left = new ArrayList();
ArrayList right = new ArrayList();
ArrayList[] result = new ArrayList[2];
if (null == list || list.size() == 0)
return result;
for (int i = 0; i < list.size(); i++) {
if (i % 2 == 0) {
left.add(list.get(i));
}
else {
right.add(list.get(i));
}
}
result[0] = left;
result[1] = right;
return result;
}
// 把一个List按照size的大小分组；
public static List splitListByParameter(List list, int size) {
if (null == list || list.size() == 0 || size == 0)
return null;
int arraySize = 0;
if (list.size() % size == 0)
arraySize = list.size() / size;
else
arraySize = list.size() / size + 1;
List result = new ArrayList(arraySize);
int temp = 0;
while (temp < arraySize) {
try {
if (temp == arraySize - 1)
result.add(list.subList(temp * size, list.size()));
else
result.add(list.subList(temp * size, temp * size + size));
}
catch (RuntimeException e) {
e.printStackTrace();
}
temp++;
}
return result;
}
/**
* 从一个LIST中随机获取size条记录，返回值LIST；
*
*/
public static List getRandomRecords(List list , int size) {
if(list==null||list.size()<=size) return list ;
List result = new ArrayList();
Random random = new Random();
while(result.size()<size){
Object obj = list.get(random.nextInt(list.size()));
if(!result.contains(obj)){
result.add(obj);
}
}
return result ;
} 
