For those of you who want to do a bit more programming. Write a well-documented class Challenge with a suitable main method for testing and methods:
- to compute the surface
of a circle. Hint: Have look in the Java API for the Math class
- to check if one
String is a substring of an other.
- to pick all the words
out of a sentence. Hint: browse the Java API.
- to reverses a String.
- that opens a window and print Hello World in it. Hint: have a look at the swing package of the API