java 加权随机简单实现

Java 权重随机简单实现例子代码

public class WeightRandomExample{

		public static void main(String [] args){
			List<DefaultWeightEntity> list = new ArrayList<>();
			list.add(new DefaultWeightEntity("A",1));
			list.add(new DefaultWeightEntity("B",2));
			list.add(new DefaultWeightEntity("C",3));
			DefaultWeightEntity defaultEntity = new DefaultWeightEntity("D",94)
			list.add(defaultEntity);
			WeightRandom<DefaultWeightEntity> weightRandom = new WeightRandom<>(list,defaultEntity);
			for(int i=0;i< 30 ;i++){
				DefaultWeightEntity entity = weightRandom.randomEntity();
				int weight = entity.getWeight();
				System.out.println(entity.getName());
			}
		}

		public interface WeightEntity{
			public int getWeight();
		}

		public class WeightRandom<T extends WeightEntity>{

			private List<T> content;
			private T defaultResult;

			public WeightRandom(List<T> content,T defaultResult){
				this.content = content;
				this.defaultResult = defaultResult;
			}

			public T randomEntity(){
				int totalWeight = content.stream().mapToInt(WeightEntity::getWeight).sum();
				int randomNum = ThreadLocalRandom.current().nextInt(totalWeight);
				Optional<T> optional = content.stream().filter(t -> {
					int result = randomNum - t.getWeight();
					return result < 0;
				}).findFirst();
				return optional.orElse(defaultResult);
			}
		}

		public class DefaultWeightEntity implements WeightEntity{

			private String name;
			private int weight;

			public DefaultWeightEntity(String name, int weight) {
				this.name = name;
				this.weight = weight;
			}

			@Override
			public int getWeight() {
				return this.weight;
			}

			public String getName() {
				return name;
			}
		}
	}