20145223 《Java Programming 》 The first 1 Weekly learning summary

Summary of the learning content of the textbook

1、JDK、JRE as well as JVM The difference between 
JDK: writing java Programming language when you need to use the compiler tools
JRE:java execution environment
JVM:java Program operating system , Its executable file is called bit code document (.class)
2、 understand PATH、CLASSPATH、SOURCEPATH And how to set them up
3、 Know how to compile and run some simple java Program
4、 Some commonly used DOS command :
for example dir : List the files in the current directory 、 Folder
md : Create directory
rd : Delete directory
cd : Enter the specified directory
cd.. : Go back to the previous Directory
cd/ : Go back to the root
del : Delete
exit : sign out dos Command line

Problems and solutions in textbook learning

1: problem : Will be .java Compiled into .class Failed in the process

To solve the process : The reasons are explained in the book , It's because I didn't tell the computer exactly where the tool program is , Follow the steps in the book , I copied the path given in the online tutorial , Change the version number to your own , Compile successfully for the first time

And after that , I use the book smoothly echo %PATH% and SET The instructions look at PATH Information and settings PATH environment variable , give the result as follows

2: problem : After setting the system variables, restart the command prompt , Find out PATH It's not set up , There is a case where you need to specify an extra path to compile successfully

To solve the process : After careful study, I found that in the setting PATH when , I didn't do what I was asked to do JDK Of bin The path to the directory is at the top of the input text box , The pop-up text box looks like this

However, the front of the text box is not in front of the first letter you see , After discovering this , The problem is solved .

Problems and resolution in code debugging

After preliminary study , I want to try to make a simple smile java Program , The code looks like this



But when my program runs , But there was such a mistake

I think this is Java and C Grammatical differences in language , I haven't mastered java I am a beginner of programming grammar , It's easy to make such a mistake . When I want to solve this problem , I found the front part of the code correct , So I modified the following part according to the previous part , In the end, the first program I wrote will run successfully

And then there's the use of NetBeans IDE Program compilation and running results of the screenshot

HelloJava! I hope that no matter what kind of problems we encounter in the future , I can keep such a positive attitude , Face with a smile .

other ( Sentiment 、 Thinking etc. , Optional )

Through the initial study , I found that these things are very basic , Just follow the steps in the book , You can't go wrong . After watching teacher Bi's video, I have a general understanding of this course . But in the process of learning, we must be careful , A small punctuation mark may cause your program not to run . I think this course is very difficult from the beginning , Now I dare to try to compile and modify the code myself , I think this is my progress , To learn is to keep trying , Constantly correct mistakes , Hard work is the only shortcut to success .

Learning progress bar

Lines of code ( newly added / The cumulative ) Amount of blog ( newly added / The cumulative ) Learning time ( newly added / The cumulative ) Important growth
The goal is 4000 That's ok 30 piece 350 Hours
The first week 200/150 2/2 15/12

Reference material

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