Java运行报错：无法找到或加载主类myRunningCode求助

Hey there, I’ve run into this exact snag before—let’s break it down and fix it quickly!

The Root Cause #

When you compiled your code with javac -cp "/temp/package.jar" myRunningCode.java, the compiler generated myRunningCode.class right in your current working directory. But when you ran java -cp "/temp/package.jar" myRunningCode, you only told the JVM to look inside the package.jar file for classes—it had no clue to check your current folder where your compiled class lives.

The Fix #

You need to add your current directory to the classpath so the JVM can locate your myRunningCode.class file. The syntax varies a bit by operating system:

• Linux/macOS: Use a colon (:) to separate classpath entries

  java -cp ".:/temp/package.jar" myRunningCode
  

• Windows: Use a semicolon (;) instead (since colons are used for drive letters here)

  java -cp ".;/temp/package.jar" myRunningCode
  

Quick Note #

The . in the classpath stands for your current working directory. By including it alongside the dependency jar, you’re telling the JVM: "Check both my current folder and the package.jar file to find all the classes I need to run this code."

内容的提问来源于stack exchange，提问作者Ques Ques