The Java Tutorials have been written for JDK 8.Java教程是为JDK 8编写的。Examples and practices described in this page don't take advantage of improvements introduced in later releases and might use technology no longer available.本页中描述的示例和实践没有利用后续版本中引入的改进,并且可能使用不再可用的技术。See Java Language Changes for a summary of updated language features in Java SE 9 and subsequent releases.有关Java SE 9及其后续版本中更新的语言特性的摘要,请参阅Java语言更改。
See JDK Release Notes for information about new features, enhancements, and removed or deprecated options for all JDK releases.有关所有JDK版本的新功能、增强功能以及已删除或不推荐的选项的信息,请参阅JDK发行说明。
Question 1: When you compile a program written in the Java programming language, the compiler converts the human-readable source file into platform-independent code that a Java Virtual Machine can understand. What is this platform-independent code called?
Question 2: Which of the following is not a valid comment:
a. /** comment */
b. /* comment */
c. /* comment
d. // comment
Question 3: What is the first thing you should check if you see the following error at runtime:
Exception in thread "main" java.lang.NoClassDefFoundError: HelloWorldApp.java.
Question 4: What is the correct signature of the main
method?
Question 5: When declaring the main
method, which modifier must come first, public
or static
?
Question 6: What parameters does the main
method define?
Exercise 1: Change the HelloWorldApp.java
program so that it displays Hola Mundo!
instead of Hello World!
.
Exercise 2: You can find a slightly modified version of HelloWorldApp
here: HelloWorldApp2.java
The program has an error. Fix the error so that the program successfully compiles and runs. What was the error?