Question: I know running `javac file1.java` produces `file1.class` if `file1.java` is the only source file, then I can just say `java file1` to run it.

However, if I have 2 source files, `file1.java` and `file2.java`, then how do I build the program?

Answer: 
or you can use the following to compile the all java source files in current directory..

```
javac *.java

```
1.[use wildcard](https://i.stack.imgur.com/lln2q.png)

2.[use options](https://i.stack.imgur.com/57O6G.png)

3.<https://docs.oracle.com/javase/8/docs/technotes/tools/windows/javac.html>