一、示例
public class TestMain {
@Data
@NoArgsConstructor
@AllArgsConstructor
@ToString
public static class Leader {
private Long employeeId;
private BigDecimal bonus;
}
@Data
@NoArgsConstructor
@AllArgsConstructor
@ToString
public static class Employee {
private Long id;
private String name;
private Boolean leader;
}
public static class FiltUtil {
public void OptionalStudy() {
Optional<Leader> leader = Optional.ofNullable(getEmployeeById(1L)
.filter(Employee::getLeader)
.map(Employee::getId)
.flatMap(this::getLeaderByEmployeeId)
.orElse(null));
if (leader.isPresent()) {
Optional.of(
leader.map(Leader::getBonus)
.map(bonus -> String.format("员工ID为1的leader奖金为：%s", bonus))
.orElse("员工ID为1的leader也没有奖金"))
.ifPresent(System.out::println);
} else {
System.out.println("员工ID为1的leader未找到，他可能只是一个基层员工，不配拥有奖金");
}
}
private Optional<Employee> getEmployeeById(Long id) {
//return Optional.of(new Employee(1L, "大老板", Boolean.TRUE));
return Optional.of(new Employee(1L, "大老板", Boolean.FALSE));
}
private Optional<Leader> getLeaderByEmployeeId(Long employeeId) {
//return employeeId == 1L ? Optional.of(new Leader(1L, BigDecimal.valueOf(1000000000))) : Optional.empty();
return employeeId == 1L ? Optional.of(new Leader(1L, null)) : Optional.empty();
}
}
public static void main(String[] args) {
// FiltUtil filtUtil = new FiltUtil();
// filtUtil.OptionalStudy();
Employee employee = new Employee(null,"",true);
//Optional.断言
// Optional.ofNullable(employee.getId()).orElseThrow(()-> new IllegalArgumentException(String.format("%s人员的Id不能为NULL", employee.toString())));
Optional.ofNullable(employee).filter(e-> StringUtil.isEmpty(e.getName())).orElseThrow(()-> new IllegalArgumentException(String.format("%s人员的name不能为空", employee.toString())));
Optional.ofNullable(employee.getName()).orElseThrow(()-> new IllegalArgumentException(String.format("%s人员的name不能为空", employee.toString())));
//Optional.非空判断
Optional.ofNullable(employee).ifPresent(o -> o.setName("UNKNOW"));
System.out.println(employee.toString());
}
}