在IT邦幫忙看到的問題，以下兩個函數，能整合為一個嗎？
public List<String> getRandom1Ary(ArrayList<ExamItemsBean> items, int count)
{
List<String> resultAry = new ArrayList<String>();
Random random = new Random();
do
{
int next = random.nextInt(items.size());
ExamItemsBean item = items.get(next);
if (!resultAry.contains(item.getAA())) // <-- 差異
{
resultAry.add(item.getAA()); // <-- 差異
}
} while (resultAry.size() < count);
return resultAry;
}
public List<String> getRandom2Ary(ArrayList<ExamItemsBean> items, int count)
{
List<String> resultAry = new ArrayList<String>();
Random random = new Random();
do
{
int next = random.nextInt(items.size());
ExamItemsBean item = items.get(next);
if (!resultAry.contains(item.getBB())) // <-- 差異
{
resultAry.add(item.getBB()); // <-- 差異
}
} while (resultAry.size() < count);
return resultAry;
}
上面方法設計的問題在於，不應該傳入ArrayList<ExamItemsBean>這一大包東西而只是為了隨機取得其中的機個元素，應該只需要傳入要隨機取得的元素就好了。
package com.abc.demo;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.stream.Collectors;
public class Main {
public static void main(String[] args) {
ArrayList<ExamItemsBean> items = new ArrayList<>();
List<String> aaList = items.stream().map(ExamItemsBean::getAA)
.collect(Collectors.toList());
List<String> bbList = items.stream().map(ExamItemsBean::getBB)
.collect(Collectors.toList());
int count = 5;
List<String> randomAry1 = getRandomAry(aaList, 5);
List<String> randomAry2 = getRandomAry(bbList, 5);
}
public static <E> List<E> getRandomAry(List<E> list, int count) {
if (list == null || list.size() < 1 || count < 1) {
return new ArrayList<E>();
}
List<E> arr = new ArrayList<E>();
Random random = new Random();
do {
int next = random.nextInt(list.size());
E e = list.get(next);
if (!arr.contains(e)) {
arr.add(e);
}
} while (arr.size() < count);
return arr;
}
}
我猜發問者應該是在博弈業要抽卡或抽老虎機圖案之類的吧。
參考：
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