201521123020 Java programming 1th Week of study summary

1. Summary of this week's study

1. Understanding of the historical development of Java

2. Learn about the differences between Java and C + +, the Java language is cumbersome to write programs, C + + concise.

3. Installing Java and JDK

2. Written work

Q1. Why are Java programs running across platforms? What are the steps to execute a Java program? (please write in your own language)

Java is run on a virtual machine, as long as there is a virtual machine, regardless of the platform. Compile the Java file into a class file, then parse the class file and run it through CMD.

Q2. What is the difference between JDK?JDK,JRE,JVM?

JDK Java SDK is the runtime environment where the JVM is a Java Virtual machine and is part of the JRE.

Q3.java HelloWorld Command, what does this parameter refer to in HelloWorld? Is it a file name? What is the meaning of this command?

Refers to the Java class name, which means that the class is executed.

What is the use of Q4.path variables? What is the use of classpath variables?

Enables the system to find the running path of the program

Q5. What is the difference between writing a program in Java and running a program and running it with the C language, and the resulting intermediate file and target file?

Java from. Java to. Class,c from. 0 to. exe

Q6. What are the 3 application versions of the Java language? What's the relationship between versions?

Java SE Java ME java EE

Q7. What is the difference between Oracle jdk and open jdk?

Oracle JDK only publishes binary installation packages, and Open JDK publishes only the source code.

3. Using the code cloud to manage Java code

Experimental summary

1. The Java language is not familiar enough and needs to be more familiar.

2. In Java programming, you can import classes directly using Import

201521123020 Java programming 1th Week of study summary