download: Towards an advanced Java interview breakout class
This course adopts the form of multiple rounds of interviews from Dachang to run through the main line, covering the required test points, high frequency points, and salary increase points for Java intermediate and advanced interviews. At the same time, we integrate the lecturer's many years of experience as an Alibaba examiner, and through real simulation of different interview scenarios, we will explain each aspect of the interview and the response experience one by one, helping you break through your own bottlenecks, perform exceptionally, and successfully pass the interview with a large factory.
Technical Requirements
Java Web1年以上实际开发经验
Environmental parameters
Environmental parameters: JDK1.8, SpringBoot2.x development tools: Intelij IDEA
In the 1990s, a single-chip computer system appeared in the hardware category. The appearance of this low-cost system immediately caused the attention of active control personnel. Because it can be used to move consumer electronics products (such as TV set-top boxes) , Bread oven, mobile phone, etc.). In order to seize market opportunities, Sun established a project team called Green in 1991. A work team consisting of Patrick, James Gosling, Mike Shelindane and several other engineers was in Menlo Park, California. A small work room on Sandhill Road discusses and develops new technologies, specializing in the embedded application of computers in home appliances.
Due to the advantages of C++, the researchers of the project group first considered choosing C++ to write programs. But for monolithic systems with extremely scarce hardware resources, C++ programs are too messy and huge. Others, because the types of embedded processor chips used in consumer electronic products are tedious, how to make programs written to work across channels is also a problem. In order to solve the difficulties, they first focused on the development of speech, assumed a simple structure and suitable for the embedded application requirements of the hardware approach system structure and drafted corresponding standards for it, and defined the binary machine of this hardware approach. Code instruction system (that is, the instruction system later called "byte code"), after the successful development of words, there will be semiconductor chip manufacturers to develop and produce this kind of hardware approach. Regarding the planning of the new language, Sun’s developers did not develop a brand-new language. Instead, they modified C++ based on the requirements of embedded software, removing some of the less practical and safety-related components left in C++. Combined with the real-time requirements of embedded systems, a policy-oriented language called Oak was developed.
Since the development of Oak language, there is no hardware way to manipulate bytecode, so in order to be able to conduct experimental research on this language during development, they based on the existing hardware and software channels, according to their own designated Standard, using software to build a working path, the whole system is simpler than C++, there is no big difference. In the summer of 1992, when the Oak language was successfully developed, the researchers demonstrated the Green operating system, Oak’s programming language, class libraries and its hardware to hardware manufacturers to convince them to use Oak language to produce hardware chips. However, The hardware manufacturers have not been very enthusiastic about this. Because they believed that the risk of producing hardware products when everyone was still ignorant of Oak language was really too great, so Oak language was unable to enter the market due to lack of hardware support, and was then put down.
In June and July 1994, after experiencing a discussion that lasted three days, the team chose to change the hard-working policy again. This time they chose to apply the technology to the World Wide Web. They think that with the arrival of the Mosaic browser, the Internet is evolving towards the same highly interactive vision, and this vision is exactly what they saw in the cable TV network. As a prototype, Patrick Norton wrote a small web browser WebRunner. [8]
In 1995, the prosperity of the Internet gave Oak time. In order to make the dull and monotonous static web pages "live", the industry urgently needs a software technology to develop a program that can be communicated through the network and can be operated across channels. Therefore, the world's major IT companies have invested a lot of manpower, material resources and financial resources for this fun. At this time, Sun company thought of the Oak that had been placed for a long time, and reviewed the test path written in software from the beginning. Because it was written in accordance with the embedded system hardware path system structure, it was very small and especially suitable for networks. The transmission system on the Internet, and Oak is also a simplified language, the program is very small, suitable for transmission on the network. Sun company first introduced an Applet (Applet is a technology that embeds applets into a web page for implementation) that can be embedded in a web page and can be transmitted on the Internet along with the web page, and renamed Oak to Java (when requesting a registered trademark, it was found Oak has been used, and after thinking about a series of names, after all, I used the Java words that the proposer accidentally mentioned when drinking a cup of Java coffee). On May 23, Sun officially released Java and HotJava browsers at the Sun world conference. Major companies such as IBM, Apple, DEC, Adobe, HP, Oracle, Netscape, and Microsoft have interrupted their related development projects, rushed to purchase Java licenses, and developed corresponding Java channels for their products. [9-10]
In January 1996, Sun released the first Java development kit (JDK 1.0), which was an important milestone in the development of Java and marked that Java became an independent development tool. In September, about 83,000 web pages were manufactured using Java technology. In October, Sun released the first just-in-time (JIT) compiler for the Java approach.
In February 1997, JDK 1.1 was released, and in the following three weeks, it reached 220,000 downloads. On April 2, the Java One conference was held with more than 10,000 attendees, setting a record for similar conferences in the world at that time. In September, the Java Developer Connection community members exceeded 100,000.
On December 8, 1998, the Enterprise Edition J2EE of the second-generation Java approach was released. In June 1999, Sun released three versions of the second-generation Java approach (referred to as Java2): J2ME (Java2 Micro Edition, a micro version of the Java2 approach), which is used in mobile, wireless and resource-limited environments; J2SE (Java 2 Standard Edition, the standard version of the Java 2 approach), used in the desktop environment; J2EE (Java 2 Enterprise Edition, the enterprise version of the Java 2 approach), used in the application server based on Java. The release of the Java 2 approach is the most important milestone in the development of Java, marking the beginning of the widespread use of Java.
On April 27, 1999, the HotSpot virtual machine was released. When the HotSpot virtual machine was released, it was supplied as an add-on program to JDK 1.2, and later it became the default virtual machine for JDK 1.3 and all other Sun JDKs afterwards [11].
One of the founders of Java: James Gosling One of the founders of Java: James Gosling
In June 2005, at the Java One conference, Sun released Java SE 6. At this moment, the various versions of Java have been renamed, and the number 2 in between has been revoked, such as J2EE renamed JavaEE, J2SE renamed JavaSE, and J2ME renamed JavaME. [12]
On November 13, 2006, Sun, the inventor of Java technology, announced that it would release Java technology as free software. Sun officially released the first batch of source codes for the Java Path Standard Edition and the executable source codes for the Java Mini Edition. Since March 2007, all developers in the world can revise Java source code[13].
In 2009, Oracle announced the acquisition of Sun [14]. In 2010, James Gosling, one of the co-founders of Java Programming Language, resigned from Oracle. In 2011, Oracle held a global event to celebrate the launch of Java7, and then Java7 was officially released. In 2014, Oracle released the official version of Java 8[15].
Programming development
correction
Programming environment
Java concept map Java concept map[16]
JDK (Java Development Kit) is called Java development kit or Java development tool, which is a program development environment for writing Java applet applets and application programs. The JDK is the center of the entire Java, including the Java Runtime Environment (Java Runtime Environment), some Java tools and Java's central class library (Java API). No matter what the Java application server is, a certain version of other JDK is built in. The mainstream JDK is the JDK released by Sun. In addition to Sun, many companies and organizations have developed their own JDK. For example, the JDK developed by IBM, Jrocket from BEA, and the JDK developed by GNU organization [17 ].
In addition, the two parts of the Java SE API subset and the Java virtual machine in the Java API class library can be collectively referred to as JRE (JAVA Runtime Environment), which is a standard environment that supports the operation of Java programs [18].
JRE is a work environment, and JDK is a development environment. Therefore, the time to write Java programs requires JDK, and the time to work Java programs requires JRE. The JDK already contains JRE, so only the JDK can be used to modify the Java program and to work the Java program normally. However, since the JDK contains a lot of content that is not related to the job, it takes up a lot of space, so the general Java program does not need to be equipped with JDK, but only needs to be equipped with JRE[19].
Programming tool
Eclipse: an open source, Java-based scalable development approach [20].
NetBeans: Open source Java integrated development environment, suitable for various clients and Web applications.
IntelliJ IDEA: It has good functions in active code prompting and code analysis. [twenty one]
MyEclipse: A commercial software developed by Genuitec, which is a widely used integrated development environment for Java applications [22].
EditPlus: Assuming that the Java compiler "Javac" and the declarator "Java" are correctly equipped, you can directly use EditPlus to compile and execute Java programs [23].
Speech characteristics
correction
1. Simplicity
Java seems to be planned like C++, but in order to make the language small and simple to understand, the planners have removed many of the features available in C++ language, which are rarely used by ordinary programmers. For example, Java does not support go to sentences, and instead provides break and continue sentences and abnormal handling. Java also eliminates C++'s operator overload and multiple inheritance features, and does not use the main file, eliminating the preprocessor. Since Java has no structure, arrays and strings are policies, so pointers are not required. Java can actively handle policy citations and direct citations, ending the active collection of useless units, so that users do not have to worry about storage and processing problems, and can spend more time and energy on development.
2. Policy-oriented
Java is a policy-oriented language. For programmers, this means paying attention to the data in the application and the method of manipulating the data, rather than strictly considering the process. In a policy-oriented system, a class is a collection of data and methods to manipulate data. Data and methods together describe the situation and behavior of the policy (object). Each policy is an encapsulation of its situation and behavior. Classes are organized in a certain system and hierarchy, so that subclasses can inherit behavior from superclasses. There is a root class in this class hierarchy, which is a class with general behavior. Java programs are organized by classes.
Java also contains a collection of extensions of classes, which form various packages (Package), which users can use in their own programs. For example, Java provides classes for generating graphical user interface components (java.awt package), where awt is an abbreviation for abstract windowing toolkit, classes for processing input and output (java.io package) and classes for supporting network functions (Java.net package).