两个测试所需文件

text
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public class Hello{
   public void sayHello(){
      System.out.println("Hello");
   }
}
text
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public class Demo{
   public static void main(String[] args) {
      Hello Hello = new Hello();
      Hello.sayHello();
   }
}

同目录下javac编译执行

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$ ls
Demo.java
Hello.java

$ javac Demo.java
$ java Demo

引入不同目录依赖编译执行

text
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$ ls
Demo.java
libs/
   Hello.java

$ javac -classpath ./libs Demo.java
$ java -classpath .:libs Demo

引入jar包

将Hello.java打成jar包

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$ cd libs
$ javac Hello.java
$ jar -cvf hello.jar Hello.class

引入jar包执行

text
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$ ls 
Demo.java
libs/
   hello.jar

$ javac -classpath ./libs/hello.jar  Demo.java
$ java -classpath .:./libs/hello.jar  Demo

优化

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$ javac -encoding UTF-8 -classpath ./libs -d classes Demo.java

# 参数说明
-encoding UTF-8   定源文件使用的字符编码
-classpath ./libs  指定查找用户类文件和注释处理程序的位置
-d classes       指定放置生成的类文件的位置，必须存在
Demo.java        source files

$ cd classes 
$ java Demo

原文地址：https://blog.csdn.net/mouday/article/details/109595005?ops_request_misc=%257B%2522request%255Fid%2522%253A%2522168475008016800180689615%2522%252C%2522scm%2522%253A%252220140713.130102334.pc%255Fall.%2522%257D&request_id=168475008016800180689615&biz_id=0&utm_medium=distribute.pc_search_result.none-task-blog-2~all~first_rank_ecpm_v1~rank_v31_ecpm-20-109595005-null-null.142^v87^insert_down28,239^v2^insert_chatgpt&utm_term=java%E4%BC%98%E5%8C%96