Java Input/Output

This worksheet explores your understanding of Java's I/O java.io.* API.

1. Write a method determines whether a file exists:

   public boolean exists(String name) {
   ...
   }
   

2. Write a method that lists the contents of a directory:

   public void ls(String name) {
   ...
   }
   

3. Write a logging method that records a string message to a file, prefixed by a timestamp:

   public void log(String fileName, String msg) {
   ...
   }
   

4. Write a method that reads 4 characters from System.in and prints them out.
5. Write "Hi, Mom!" to a StringWriter and then dump the string to make sure you wrote it.