Practice Links

1) https://www.ntu.edu.sg/home/ehchua/programming/java/J3f_OOPExercises.html#zz-1.5 --some examples
2) http://www.inf.ed.ac.uk/teaching/courses/inf1/op/Labs/2008/doc/lab2.html
3) https://practiceit.cs.washington.edu/problem/list
4) https://codingbat.com/java