Problem scenario
You copied a Java program from the Internet. You named the file foobar.java. You try to compile it (e.g., with "javac foobar.java"), but you get this error:
foobar.java:6: error: class ContInt is public, should be declared in a file named ContInt.java
public class ContInt
^
1 error
What do you do?
Solution
Rename foobar.java to be ContInt.java.