Use Javac and Java commands in a CMD window to compile and execute a class with an inheritance relationship with the package name

I. BACKGROUND

When I recently wrote Java code with a package name and inherited relationships using Notepad and ran it, I found a lot of errors, and after trying to solve them, let's look at what problems we will meet and give solutions.

Second, the test process

1. Parent Class Code

1  PackageCom.hafiz.zhang;2 3  Public classFu4 {5     PrivateInteger i;6 7      Public voidSayHello (String name) {8System.out.println ("Hello" +name);9     }Ten}

2. Sub-class Code

1  PackageCom.hafiz.zhang;2 3  Public classZiextendsFu4 {5     Private StaticString name = "Hafiz.zhang";6      Public Static voidMain (string[] args) {7         NewZi (). SayHello (name); 8     }9}

1) The first time you run the Javac Zi.java command directly in the same directory as the base class and subclass, the following error occurs:

The workaround is that we need to run with the Javac *.java command, because there is an inheritance relationship, and the child class is compiled with the parent class first

2) Run the Java Zi command with the following error

What is the reason for this? Because we use the package name when we write the program, we need the full name when we run the class file, the command is modified to: Java Com.hafiz.zhang.Zi

We will find the following error

This is because we do not have a subfolder Com/hafiz/zhang and the Zi.class file does not exist under the subfolder, so the main class cannot be found.

The solution: Use javac-d. *.java ("-D." Represents the Create package path in the current directory) command to compile, so the Javac command automatically helps us create the folder specified by the package name and creates a Zi.class file under that folder.

At this point we also find that the subfolder Com/hafiz/zhang has been automatically generated and that there is a Zi.class file under that subfolder.

Then we run: Java com.hafiz.zhang.Zi command, program execution success!

This leads us to the way in which the CMD window uses Javac and Java commands to compile and execute a class with an inheritance relationship with the package name:

1. Use javac-d. *.java to compile

2. Use the Java Com.hafiz.Zi (class full name with package names) command to run!

Use Javac and Java commands in a CMD window to compile and execute a class with an inheritance relationship with the package name