Thinking logic of computer programs (80) and thinking 80
This section describes scheduled tasks. There are many application scenarios for scheduled tasks, such:
An alarm program or task reminder. You can call a bed at a specified time or return a credit card on a specified date.
The monitoring system collects system data at intervals to trigger alarms for abnormal events.
Statistical System, which usual
Thinking logic of computer programs (49), thinking 49
Previously, we introduced two implementation classes HashMap and TreeMap of the Map interface. This section introduces another implementation class LinkedHashMap. It is a subclass of HashMap, but it can keep the elements sorted by insert or access, which is different from the TreeMap key sorting.
It is easy to understand the order by insert. What does th
bigger. For example, when you put data from a database into memory, you can use the SQL ORDER BY statement to have the database sort the data.Ordered by AccessLet's take a look at an orderly example with the following code:New true ); Accessmap.put ("C", [+]),accessmap.put ("D", "a"),Accessmap.put ("A", "a"); Accessmap.get ("C"); Accessmap.put ("D"); for (entry Entry:accessMap.entrySet ()) { System.out.println (Entry.getkey ()+ "" + Entry.getvalue ());}Each access moves the key-value pair t
Thinking logic of computer programs (5), thinking Logic
Intuitive fact violations
The reason why a computer is called a "computing" machine is because it was invented mainly for computing. "computing" is of course its specialty. In everyone's impression, computing must be very accurate. But in fact, even in some basic
Thinking logic of computer programs (79), thinking 79
In the previous section, we mentioned that in asynchronous task programs, a common scenario is that the main thread submits multiple asynchronous tasks and then processes the results if a task is completed, in this scenario, Java provides a convenient method for sending and distributing packets. The Completion
Thinking logic of computer programs (45) and thinking 45
The previous sections introduced the basic container classes in Java. Each container class has a data structure behind it. ArrayList is a dynamic array, sorted list is a linked list, And HashMap/HashSet is a hash table, treeMap/TreeSet is a red-black tree. This section describes another data structure-heap.
How to view all computer programs in Windows XP
Although Microsoft no longer supports the XP system, it may be a habit of using many people. Recently, user feedback from the XP system is provided. To better understand your computer, you can view all the programs in the computer
Thinking logic of computer programs (30), thinking Logic
The previous section introduced the String, and mentioned that if String modification operations are frequent, StringBuilder and StringBuffer classes should be used. The methods of these two classes are basically the same, and their implementation code is almost the same, the only difference is that StringBuffer is thread-safe, while StringBuilder is
The AT program runs the commands and programs on the computer at the specified time and date. The AT command can only be used when the schedule service runs. If used without parameters, at lists the scheduled commands.
Grammar
at [\\ComputerName] [{[ID] [/delete]|/delete [/yes]}]
at [[\\ComputerName] hours:minutes [/interactive] [{/every:date[,...]|/next:date[,...]}] Command
Parameters
\\computername
Spe
A fact that violates intuitionThe computer is called "Computing" machine is because it is mainly used to calculate the invention, "calculation" of course is its expertise, in everyone's impression, the calculation must be very accurate. But in fact, even in some very basic decimal operations, the results of the calculations are imprecise.Like what:
float F = 0.1f*0.1f;
System.out.println (f);
Windows Internet Explorer 8 cannot be installed in xp sp3 because other programs or updates are waiting to restart your computer. solution:
Cause: the "Install update" button is selected during IE8 installation, and the IE-based third-party browser is not closed during installation. After the installation is completed and restarted, the installation fails. (Normally, ie is successfully upgraded aft
Thinking logic of computer programs (59) and thinking 59
The previous two sections show you how to read and write file content through a stream. This section describes operations on file metadata and directories.
File and directory operations are ultimately related to the operating system and file system. The implementations of different systems are different, but Java. io. the File class provides a unified
Thinking logic of computer programs (78) and thinking 78
In the previous section, we initially discussed the task execution service in Java and package. In reality, the main implementation mechanism of the task execution service is the thread pool. In this section, we will discuss the thread pool.
Basic Concepts
A thread pool, as its name implies, is a thread poo
Document directory
Multi-line and single-line JS Console
Extended reading: Interpreter and Compiler
Interactive Language
Test in the Javascript Console
Test in ironscheme
I recently read the construction and interpretation of computer programs (the second edition of the original book) and learned about the library Programming Language LISP dialect scheme. This non-mainstream programming language de
Thinking logic of computer programs (58) and thinking 58
In the previous section, we introduced how to process files in byte streams. we mentioned that for text files, byte streams do not have the encoding concept and cannot be processed by row, which is inconvenient to use, it is more suitable to use the streaming. This section describes the streaming.
First, we will briefly introduce the
Thinking logic of computer programs (39) and thinking 39
In the previous section, we introduced the ArrayList. the random access efficiency of ArrayList is very high, but the insertion and deletion performance is relatively low. We mentioned that the List interface's parallel List is also implemented, its features are almost the opposite of that of ArrayList. This section describes the feature list in detai
Thinking logic of computer programs (53), thinking 53
The previous sections introduced various specific container classes and abstract container classes. As we mentioned above, Java has a collection class that provides many common functions for container interfaces, these functions are provided in static mode.
What functions are available? There are two possible types:
For the first type, operations can be
Network basics of basic computer series-network protocols and basic computer networks
What's the network protocol
A computer with hardware, operating systems, and software already has functions that can be used. However, to realize communication between a
MySQL Installation and startup services, as well as the problems encounteredMySQL version: mysql-5.7.13-winx64.zip (Install-free, unzip the program folder, such as C:\Program files\mysql-5.7.13-winx64): Http://dev.mysql.com/get/Downloads/MySQL-5.7/mysql-5.7.13-winx64.zipProblems encountered:1. MySQL Service has been installed successfully, created an empty data folder, also filled in the initialization INI file, but could not start2. Cmd execution instruction "mysql-uroot-p" prompt: "error 2003
Thinking logic of computer programs (74) and thinking 74
This section describes a commonly used concurrent container-ConcurrentHashMap, which is a concurrent version of HashMap. Compared with HashMap, it has the following features:
Concurrency Security
Directly supports atomic composite operations
Supports high concurrency, fully parallel read operations, and parallel write operations to a certain exten
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