java | 易学教程

知乎万赞：计算机应届生月薪大多是多少？

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注：这个回答是我一位朋友在知乎上的万赞匿名回答，取得了他的同意，特此在这里转发，并写下一点自己的感想。 (但是，想了下，由于这个回答是匿名的，似乎也很难证明这个回答就是我朋友的。。。但是我让他在回答下帮我置顶了一条的评论，应该勉强算一个证明了哈哈哈) 问题: 计算机应届生月薪大多是多少？月薪4k，6k，8k，10k的各占百分之多少呢，想了解一下知乎上大家的就业情况。好对自己有个定位，亲身经历或者朋友同学什么的都可以说说哈。我的朋友回答：能做到以下几点，绝对可以在北上杭深拿到15K（小北注：这是18年的回答了）以上: 撒比算法题，各大公司笔试面试基本都考这个，别的不说，《剑指offer》所有题目背下来，leetcode刷个四五百题起码的吧。搞过ACM也可以，反正刷个四五百题是必须的。我也觉得考这些撒比算法题很撒比，但是大家都这么考，你不准备，那不挂你挂谁？数据结构，不说要彻底给面试官手推各种数据结构的均摊复杂度，也不要求你手写红黑树，至少AVL 哈希表堆这些简单的数据结构得自己实现过；链表、线性表必须熟悉到不能再熟悉，比如vector为什么要用加倍扩容而不是每次增加一个固定的扩容容量；BBST各种都能扯一下，达到这个程度就差不多了。计算机组成原理, 至少《深入理解计算机系统》得过一遍吧？配套实验也得做一下吧？计算机网络，这个最简单了，随便找本书，把应用层、传输层看完就行

Converting PNG byte array to JPEG byte array in java

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问题 I am not sure what I am exactly doing here so please give some advise and forgive the mistakes. I have a image byte[] called idCardImage and I did the following to convert it to a String: String s = new String(idCardImage); And it prints out like this: data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABQAAAAUCAYAAACNiR0NAAAEHUlEQVQ4TzWUW49VRRCFv6rq3ufMmTNn.... Did some search online and it seems this image is in a png format with base 64 encoded. What I need to do is to convert it to a jpeg

How knows Stream.toArray(Book[]::new); how many elements the array has and where is the implementation of “Book[]::new”

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问题 I'm triying to understand method references and I don't know how with this "Book[]::new" it can create an array with the right number of elements. Book[] arrayBook = stBooks.toArray(Book[]::new); In order to create the array when I use the second and third option I have to specify a Functional Interface that Receive an Int and return a new Array. But, in the first option I don't know where is the implementation and where you specify the number or elements that is going to have the array. I

Java Swing, all images appear pixelated

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问题 Every image in my Java Swing Programs will appear in low quality as shown below: As you can see from the image, it is not just images I am having problem with, it's graphics in general displaying like this. In the right portion you can see the problem reflected to a JFreeChart Graphic. Has anyone else had this problem, is it related to the graphics card or maybe windows DPI? The same programs will render perfectly fine in other machines so I am pretty sure it is not related to the code. 回答1:

Java Swing, all images appear pixelated

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Two javafx Integer Spinners bound bidirectional: why is the binding unreliable?

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问题 I am trying to practice my binding. I want to make a window with two spinners and just get them to show the same value. The problem is that the binding is unreliable: the spinners seem to stop updating each other if they are clicked too fast. Both spinners still respond to clicking, and clicks are counted correctly on the spinner being clicked, but the other spinner stops updating and never recovers. And it doesn’t have to be very fast clicking at all to cause it. My code is based on this

Spring Security custom RememberMeAuthenticationFilter not getting fired

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问题 I have implemented 'Remember Me' functionality in my Spring MVC application using Spring Security 3.1 My security-context.xml looks like this : <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:security="http://www.springframework.org/schema/security" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www

Integer partitioning in Java

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问题 I'm trying to implement a program that returns the number of existing partitions of an integer n as part of an assignment. I wrote the code below, but it returns the wrong number (Partitions n returns the result of Partitions n-1). I don't get why this happens. I've tried many things and still don't know how to fix it, can anyone please help me? [edited code out to avoid plagiarism from my colleagues :p] m stands for the biggest number allowed in a partition, so partition(4,4) would be 5 = 4,

Java XPath umlaut/vowel parsing

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问题 I want to parse the following xml structure: <?xml version="1.0" encoding="utf-8"?> <documents> <document> <element name="title"> <value><![CDATA[Personnel changes: Müller]]></value> </element> </document> </documents> For parsing this element name="????? structure I use XPath in the following way: XPath xPath = XPathFactory.newInstance().newXPath(); String currentString = (String) xPath.evaluate("/documents/document/element[@name='title']/value",pCurrentXMLAsDOM, XPathConstants.STRING); The

Java XPath umlaut/vowel parsing

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