Collectors.toMap不允许Null Value导致NPE

发表于 2021-10-13 分类于 Java 本文字数： 880 阅读时长 ≈ 3 分钟

背景

线上某任务出现报警，报错日志如下：

java.lang.NullPointerException: null
        at java.util.HashMap.merge(HashMap.java:1225)
        at java.util.stream.Collectors.lambda$toMap$58(Collectors.java:1320)
        at java.util.stream.ReduceOps$3ReducingSink.accept(ReduceOps.java:169)
        at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1380)
        at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
        at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
        at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)
        at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
        at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499)
        at com.xxx.web.controller.TaskController.getOmsAccidCloudCCUserIdMap(TaskController.java:648)
        at com.xxx.web.controller.TaskController.executePushNewRegisterLead(TaskController.java:400)
        at com.xxx.web.controller.TaskController.pushNewRegister(TaskController.java:145)

对应出错的代码：

omsAccidCloudCCUserIdMap = administratorList.stream()
.collect(Collectors.toMap(Administrator::getAccid,administrator
-> cloudccAccidUserIdMap.get(administrator.getCloudccAccid())));

已知administratorList不含有null元素，administratorList、cloudccAccidUserIdMap都不为null，Administrator::getAccid也不会返回null值。

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figlet字符日期刷新

发表于 2021-10-06 分类于编程技术本文字数： 164 阅读时长 ≈ 1 分钟

!/bin/bash

function timediff() {
    # time format:date +"%s.%N", such as 1502758855.907197692
    start_time=$1
    end_time=$2

    start_s=${start_time%.*}
    start_nanos=${start_time#*.}
    end_s=${end_time%.*}
    end_nanos=${end_time#*.}

    # end_nanos > start_nanos?
    # Another way, the time part may start with 0, which means
    # it will be regarded as oct format, use "10#" to ensure
    # calculateing with decimal
    if [ "$end_nanos" -lt "$start_nanos" ];then
        end_s=$(( 10#$end_s - 1 ))
        end_nanos=$(( 10#$end_nanos + 10**9 ))
    fi

# get timediff
    time=$(( 10#$end_s - 10#$start_s )).`printf "%03d\n" $(( (10#$end_nanos - 10#$start_nanos)/10**6 ))`
    echo $time
}

# 退出时清空屏幕
trap "clear;exit" 2
# 清空首屏
clear
# 隐藏光标
echo -e "\033[?25l"

diff=0
str=`date  +'%Y / %m / %d %H : %M : %S'`
while true
do
    figlet -w 120 -f big -c "${str}"

    start=$(date +'%s.%N')
    str=`date  +'%Y . %m . %d - %H : %M : %S'`
    echo -ne "$report"
    echo -ne "\033[1;1H"
    a=`timediff $start $end`
    b=1
    end=$(date +'%s.%N')

    sleep `awk 'BEGIN{print "'$end'" - "'$start'"}'`
done

Vim-easy-align 表格格式化/对齐插件

发表于 2021-10-05 分类于 Vim 本文字数： 1.1k 阅读时长 ≈ 4 分钟

非常强大的对齐格式化插件; 对于编辑 Markdown 的 table 来说简直就是量身定制神器
支持的分隔符: <Space> = : . | & # ,

安装

vundle` 方式安装: `vim ~/.vimrc
" 找到 call vundle#begin() 和 call vundle#end() 之间插入
plugin 'junegunn/vim-easy-align'


" 然后直接在 vim 里用命令方式安装
:source %
:plugininstall


" 文件末尾增加配置
" start interactive easyalign in visual mode (e.g. vipga)
xmap ga <plug>(easyalign)

" start interactive easyalign for a motion/text object (e.g. gaip)
nmap ga <plug>(easyalign)

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Java 8 Tutorial

发表于 2021-10-02 分类于 Java 本文字数： 616 阅读时长 ≈ 2 分钟

This is a complete guide to Java 8 features, enhancements, date and time API, and coding examples. The examples from this tutorial are tested in our local development environment. You can simply clone from Github and try to use it in your projects or practice.

New Tutorials added (2020)

Key Features of Java 8

In this tutorial, we will learn the following important keys features that came in Java 8:

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Maven-Scope

发表于 2021-10-02 分类于 Maven 本文字数： 1.2k 阅读时长 ≈ 4 分钟

https://maven.apache.org/guides/introduction/introduction-to-dependency-mechanism.html

Maven 中的依赖作用范围概述

Maven中使用 scope 来指定当前包的依赖范围和依赖的传递性。常见的可选值有：compile, provided, runtime, test, system 等。scope 主要是用在 pom.xml 文件中的依赖定义部分，例如：

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-test</artifactId>
    <version>3.2.1.RELEASE</version>
    <scope>test</scope>
</dependency>

scope 各种取值详解

scope 取值	有效范围（compile, runtime, test）	依赖传递	例子
compile	all	是	spring-core
provided	compile, test	否	servlet-api
runtime	runtime, test	是	JDBC 驱动
test	test	否	JUnit
system(弃用)	compile, test	是

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