Java 使用Stream()过滤(filter)筛选List<T>列表数据并记录过滤的值日志方法代码

示例代码：

List persons = Arrays.asList(new Person("John"), new Person("Paul"));

1､使用filter()进行过滤筛选数据

List filtered = persons.stream()
      .filter(p -> {
          if (!"John".equals(p.getName())) {
              return true;
          } else {
              System.out.println(p.getName());
              return false;
          }})
      .collect(Collectors.toList());

或

//使用包装器private static  Predicate andLogFilteredOutValues(Predicate predicate) {    return value -> {        if (predicate.test(value)) {            return true;        } else {            System.out.println(value);            return false;        }    };}List persons = Arrays.asList(new Person("John"), new Person("Paul"));List filtered = persons.stream()  .filter(andLogFilteredOutValues(p -> !"John".equals(p.getName())))  .collect(Collectors.toList());

2､collect()和Collectors.partitioningBy()进行过滤筛选数据

Map> map = persons.stream()
    .collect(Collectors.partitioningBy(p -> "John".equals(p.getName())));
System.out.println("filtered: " + map.get(true));
List result = map.get(false);

或

List result = persons.stream()
    .collect(Collectors.collectingAndThen(
        Collectors.partitioningBy(p -> "John".equals(p.getName())),
        map -> {
            System.out.println("filtered: " + map.get(true));
            return map.get(false);
        }));