摘要:importjava.util.ArrayList;importjava.util.List;publicclassCollectionGroupUtil{publicstaticListgroupListByQuantity(Listlist,intquantity){if(list==null||list.size()==0){returnlist;}if(quantity˂=0){newIl
import java.util.ArrayList;
import java.util.List;
public class CollectionGroupUtil {
public static List groupListByQuantity(List list, int quantity) {
if (list == null || list.size() == 0) {
return list;
}
if (quantity <= 0) {
new IllegalArgumentException("Wrong quantity.");
}
List wrapList = new ArrayList();
int count = 0;
while (count < list.size()) {
wrapList.add(list.subList(count, (count + quantity) > list.size() ? list.size() : count + quantity));
count += quantity;
}
return wrapList;
}
}
import java.util.ArrayList;
import java.util.List;
import org.junit.Test;
public class CollectionGroupUtilTest {
/**
* 大于分组数量的情况
*/
@Test
public void test() {
List<String> allList = new ArrayList<String>();
for (int i = 1; i <= 504; i++) {
allList.add(i + "");
}
List<List<String>> groupList = CollectionGroupUtil.groupListByQuantity(allList, 50);
int i = 0;
List<String> list = null;
for (int c = 0; c < groupList.size(); c++) {
list = groupList.get(c);
System.out.println("第" + (c + 1) + "组: ");
for (String temp : list) {
System.out.print(temp + ", ");
}
System.out.println();
}
}
/**
* 小于分组数量的情况
*/
@Test
public void test2() {
List<String> allList = new ArrayList<String>();
for (int i = 1; i <= 45; i++) {
allList.add(i + "");
}
List<List<String>> groupList = CollectionGroupUtil.groupListByQuantity(allList, 50);
int i = 0;
List<String> list = null;
for (int c = 0; c < groupList.size(); c++) {
list = groupList.get(c);
System.out.println("第" + (c + 1) + "组: ");
for (String temp : list) {
System.out.print(temp + ", ");
}
System.out.println();
}
}
/**
* 集合只有一个记录的情况
*/
@Test
public void test3() {
List<String> allList = new ArrayList<String>();
for (int i = 1; i <= 1; i++) {
allList.add(i + "");
}
List<List<String>> groupList = CollectionGroupUtil.groupListByQuantity(allList, 50);
int i = 0;
List<String> list = null;
for (int c = 0; c < groupList.size(); c++) {
list = groupList.get(c);
System.out.println("第" + (c + 1) + "组: ");
for (String temp : list) {
System.out.print(temp + ", ");
}
System.out.println();
}
}
/**
* 空集合的情况
*/
@Test
public void test4() {
List<List<String>> groupList = CollectionGroupUtil.groupListByQuantity(null, 50);
System.out.println(groupList);
groupList = CollectionGroupUtil.groupListByQuantity(new ArrayList(), 50);
System.out.println(groupList);
}
/**
* 集合刚满一个分组的情况
*/
@Test
public void test5() {
List<String> allList = new ArrayList<String>();
for (int i = 1; i <= 50; i++) {
allList.add(i + "");
}
List<List<String>> groupList = CollectionGroupUtil.groupListByQuantity(allList, 50);
int i = 0;
List<String> list = null;
for (int c = 0; c < groupList.size(); c++) {
list = groupList.get(c);
System.out.println("第" + (c + 1) + "组: ");
for (String temp : list) {
System.out.print(temp + ", ");
}
System.out.println();
}
}
}