package jp.co.jid.exBasic; import java.util.ArrayList; import java.util.HashSet; import java.util.List; public class MyList { private static final int RANDOM_NUMBER = 101; public List<Integer> getRondomNumberList(int count) { ArrayList<Integer> list = new ArrayList<Integer>(); for (int i = 0; i < count; i++) { list.add(Integer.valueOf((int)(Math.random() * 101))); } return list; } public List<Integer> getRondomNumberDuplicationList(int count) { if (count > RANDOM_NUMBER) { return null; } ArrayList<Integer> list = new ArrayList<Integer>(); while (list.size() < count) { Integer integer = Integer.valueOf((int)(Math.random() * RANDOM_NUMBER)); if (!list.contains(integer)) { list.add(integer); } } return list; } public List<Integer> getRondomNumberDuplicationList2(int count) { if (count > RANDOM_NUMBER) { return null; } ArrayList<Integer> list = new ArrayList<Integer>(); HashSet<Integer> set = new HashSet<Integer>(); while (set.size() < count) { set.add(Integer.valueOf((int)(Math.random() * RANDOM_NUMBER))); } return list; } }