用ArrayList重新实现权重随机类

hutool-core/src/test/java/cn/hutool/core/lang/WeightListPoolTest.java

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+package cn.hutool.core.lang;
+
+import cn.hutool.core.util.RandomUtil;
+import org.junit.jupiter.api.Test;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class WeightListPoolTest {
+
+	@Test
+	public void weightRandomTest() {
+		Map<Integer, Times> timesMap = new HashMap<>();
+		int size = 100;
+		double sumWeight = 0.0;
+		WeightListPool<Integer> pool = new WeightListPool<>(size);
+		for (int i = 0; i < size; i++) {
+			double weight = RandomUtil.randomDouble(100);
+			pool.add(i, weight);
+			sumWeight += weight;
+			timesMap.put(i, new Times(weight));
+		}
+
+		double d = 0.0001;// 随机误差
+		int times = 100000000;// 随机次数
+		for (int i = 0; i < times; i++) {
+			timesMap.get(pool.random()).num++;
+		}
+		double finalSumWeight = sumWeight;
+		timesMap.forEach((key, times1) -> {
+			double expected = times1.weight / finalSumWeight;// 期望概率
+			double actual = timesMap.get(key).num * 1.0 / times;// 真实随机概率
+			assertTrue(Math.abs(actual - expected) < d);// 检验随机误差是否在误差范围内
+		});
+	}
+
+	private static class Times {
+
+		int num;
+
+		double weight;
+
+		public Times(double weight) {
+			this.weight = weight;
+		}
+	}
+}