20145207 the first week of Java Program Design Study summary

Sorry, it's late.

    Other first don't say, first apologized, before the holiday with Lou teacher How many have some contradictions, hope to forgive.

   Holiday Busy Internship There are some other things, in order to take this course seriously, the rest of the time to stay, for a day a chapter to make up.

    Because no class and another course did not open the reason, the students have learned this course, I now re-learn! Of course, it also brought me a lot of convenience. First of all, by looking at some students of the blog to listen to the suggestions of good friends, Lou Teacher's teaching methods, assessment mode and the form of writing a blog to write a general understanding.

    Let's talk about your self-study content:

1.   first JDK. This is frankly not going to make it, it is good to take a vacation before the matter, let Chenjunda help on the computer has installed the Java environment. and observed the previous classmate's Java compilation system, I chose my eclipse, feel more useful.  

2.      

• Java's three major platforms--java SE (Java standard Edition), Java EE (Java Enterprise Edition), Java ME (Java Micro Edition). Java EE, which is based on Java SE, is suitable for developing applications. Java me is a platform for developing and deploying applications on small digital devices. My main learning is Java SE.

• Java SE has four components. The JVM (Java Virtual machine), JRE (Java Runtime enviromnent), JDK (Java development Kits), Java language, respectively. The JVM is a virtual machine, the only operating system known to the Java program, and its executable file is a . class file. The JRE is the Java execution environment. JDK is a tool program with JRE that develops Java prerequisites.

• When an instruction is executed under the entity operating system, it is based on the path information in path. The JVM is the only virtual operating system that the Java program recognizes, and according to Classpath, the path information of the class execution file is specified.

    Some basic DOS instructions to facilitate human-computer interaction.
Dir: Lists the files and folders in the current directory
MD: Creating a Directory
RD: Deleting a directory
CD: Enter the specified directory
CD: Back to top level directory
Cd/: Go back to the root directory
Del: Delete Files
Exit: Launch DOS command line

    Next, I will briefly talk about my understanding of jvm/jre/jdk. The JVM is the meaning of the Java Virtual machine, the. class file can run, or the system cannot run directly. The book also emphasizes its importance, emphasizing that "the JVM is the only operating system known to the Java program, and its executable file is a. Class document" important concept. The JRE refers to the Java operating environment, that is, Java program to execute, always have a suitable environment for it, like C language, the same needs the environment, it is impossible to simply execute them. The JDK contains some Java language development tools that must be installed in order to develop Java programs. In summary, the JVM is necessary to read Java programs, and the JRE provides an environment for running Java programs, and the JDK provides development tools for Java programs. As a result, the three are included, and the JDK includes the JRE,JRE and the JVM. Java's cross-platform is embodied in Java has a different version of the JDK, can be used for Windows, Linux, Max and other operating systems, Java programs are unchanged, only need to change the corresponding JDK, you can develop running Java programs on any platform.

Then I started my first program "Hello World" with the textbook. Hit the Code of "Hello World" as in the code of the book.

  roughly understand the meaning of the program, class represents a class, HelloWorld is the name of the class, because class is preceded by public, so HelloWorld is still an open class, A. Java document can have multiple classes, but only one public class, and when there is a public class, ensure that the. Java document name matches the public class name. "public staticvoid Main (string[] args)" is a bit like the sentence in C, and the main and C language also feel similar, is the entry point of the program. The following sentence can be broadly understood, is to print out "Hello World" this string of characters. The curly braces represent chunks, and the C language should be the same.
The program diagram is as follows:

The first procedure is done, I hope Lou teacher can see my attitude

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Maybe that's it, tomorrow the second chapter goes up, yes, I heard there is a questionnaire, one will fill up

20145207 the first week of Java Program Design Study summary