JAVA8新特性lambda表达式（操作List）

两个List通过相同的属性值进行个别属性赋值

需求：List<UserVo> 用户对象 List<CustLoginLogVo> 用户登录对象，将CustLoginLogVo集合中按用户全局ID进行匹配把用户的最后登录时间set到对应的UserVo中

UserVo:

public class UserVo{
    @ApiModelProperty(value = "用户全局ID")
    private String custGlobalId;
 
    @ApiModelProperty(value = "最后登录时间")
    private Date lastLoginTime;
}

CustLoginLogVo:

public class CustLoginLogVo{
    @ApiModelProperty(value = "用户全局ID")
    private String custGlobalId;
 
    @ApiModelProperty(value = "最后登录时间")
    private Date lastLoginTime;
}

实现代码：

List<UserVo> userList = new ArrayList<>();//这里要非空
List<CustLoginLogVo> custLoginLogVos =  new ArrayList<>();//这里要非空 业务代码不贴出来
            if(ValidateHelper.isNotEmptyCollection(custLoginLogVos)) {
                userList = userList
                        .stream()
                        .map(user -> custLoginLogVos.stream()
                                .filter(log -> user.getCustGlobalId().equals(log.getCustGlobalId()))
                                .findFirst()
                                .map(log -> {
                                    user.setLastLoginTime(log.getLoginTime());
                                    return user;
                                })
                                .orElse(user))
                        .collect(Collectors.toList());
            }

补充一点 Variable used in lambda expression should be final or effectively

            int[] i = {1};
            int j = 0;
            List<CustLoginLogVo> custLoginLogVos = custLoginLogQueryRepository.listLastLogin(param);
            custLoginLogVos.forEach(c->{{
              i[0] = 1; //arr绕过
              //j = 1; Variable used in lambda expression should be final or effectively final 
            }
            });

对集合抽取属性求和

//获取阅读数
      Integer readTatol =  msgBrowseVos
                              .stream()
                              .filter(msgBrowse -> msgBrowse.getMsgType().equals(MsgBrowseConstants.msgType.READ))
                              .mapToInt(MsgBrowseVo::getCount)
                              .max()
                              .orElse(0);
      //获取分享数
      Integer shareTatol = msgBrowseVos
                              .stream()
                              .filter(msgBrowse -> msgBrowse.getMsgType().equals(MsgBrowseConstants.msgType.SHARE))
                              .mapToInt(MsgBrowseVo::getCount)
                              .max()
                              .orElse(0);