201521123100 the first week of Java Program Design Study summary

Java First Week Learning summary

1. Learn about Java and its development environment, learn the use of notepad++&eclipse development software

2. Proficient in using notepad++ to run the first Java program "Hello World" and learn how to use cmd

3. Easy to master the use of eclipse, but still less skilled, will be more skilled in the next week to use eclipse

Written work

1. Why are Java programs running across platforms? What are the steps to execute a Java program? (please write in your own language)

Because Java is compiled and run on the virtual machine, unlike the C language requirement to compile under a fixed platform;

Programming-compile-run;

2. What is the difference between a JDK?JDK,JRE,JVM?

JDK is the Java language Software Development kit;

The JDK is the Java development environment, the JVM is the virtual machine, the JRE is the Java execution environment;

3.What does the HelloWorld parameter refer to in the Java HelloWorld command? is it a file name? What is the meaning of this command?

HelloWorld is the file name when the code is saved; This command is the program that runs the HelloWorld file;

4. What is the purpose of setting the path variable? What is the use of classpath variables?

Allows the system to find the instruction to execute in path; theclasspath variable is the path to the Java load class (class or Lib). Only classes in the path set by Classpath can be loaded.

5. What is the difference between writing a program in Java and running a program and running it with the C language, and the intermediate and target files that are generated?

Java source files:. java

Java executable file:. class

C Language Source files:. cpp

C Language Intermediate file:. obj

C Language destination file:. exe

6.What are the 3 application versions of the Java language? What is the relationship between versions?

Java SE, Java ee, Java me three application versions, Java SE is the foundation of each application platform, including the JVM,JRE,JDK and Java language four main parts; Java EE defines a series of services, APIs, protocols, etc., based on Java SE; java Me is the smallest of the Java platform versions and is designed to be the platform for developing and deploying applications on small digital devices;

7.What is the difference between Oracle jdk and open jdk?

Oracle JDK Implementation is the Sun JDK implementation, Oracle JDK using JRL, and open JDK using the GPL, the former source code can be used for personal research use, but prohibit any commercial use, the latter allows commercial usage;

8.What are the main applications of Java? What are your goals and expectations in this course?

Network programming, enterprise-level development, mobile phone development;

Proficient in the use of Java language, can use Java to complete small development;

201521123100 the first week of Java Program Design Study summary