上课重点记一下:

assert = 程序运行到此该Boolean为true方能继续
• Statement to test assumptions about your program;
- Helps detect logic bugs
- Documents code

Java assert statement. Throws exception unless Boolean condition is true.
assert isSorted(a, lo, hi ;
Can enable or disable at run time. No cost in production code.
java -ea MyProgram //enable assertions
java -da MyProgram //disable assertions (default)

comparable:
comparator：

degenerate line segment == point;