Lambda表达式使用整理

1、List转换

List<String> departmentIdList = userList.stream().map(e -> e.getDepartmentId()).collect(Collectors.toList());

2、List转换并且转换为Set

Set<String> departmentIdSet = userList.stream().map(e -> e.getDepartmentId()).filter(e -> ValidateUtil.isNotNull(e)).collect(Collectors.toSet());

3、过滤

Set<String> departmentIdSet = userList.stream().map(e -> e.getDepartmentId()).filter(e -> ValidateUtil.isNotNull(e)).collect(Collectors.toSet());

4、List转换为Map

Map<String, String> deptMap = userDeptList.stream().collect(Collectors.toMap(e -> e.getDeptId(), e -> e.getDeptName()));

Lambda表达式使用整理

原文：https://www.cnblogs.com/dancser/p/12560927.html