Презентация на тему Exceptions and testing

program behaves not in expected way
2 + 2 =

5
2 + 2 = 4 … but takes 20 seconds to calculate
1 / 0 … 1.0 / 0.0
File.open(“???123321\5431`”);
a = null; a.equals(b);
Exception – problem, that can be detected as something “not expected to happen” (“exceptional”) and handled in your code. In Java language exceptions are implemented as specific kind of objects and operators to handle them.

Throwable
/

\
Error Exception
|
RuntimeException

Exception
Errors are either compilation errors or serious problems that

should not be handled

Checked (“predictable”) vs Unchecked exceptions
All Errors are Unchecked exceptions

language? In simple language: Exception which are checked at

Compile time called Checked Exception. Some these are mentioned below. If in your code if some of method throws a checked exception, then the method must either handle the exception or it must specify the exception using throws keyword.

IOException
SQLException
DataAccessException
ClassNotFoundException
InvocationTargetException
MalformedURLException

whose handling is NOT verified during Compile time. These

exceptions occurs because of bad programming. The program won’t give a compilation error. All Unchecked exceptions are direct sub classes of RuntimeException class.

NullPointerException
ArrayIndexOutOfBound
IllegalArgumentException
IllegalStateException

that allows to check if parts (units) of your

program behaves right in automatic way
There are few frameworks to implement Unit test. JUnit is pre-installed for Eclipse.

handle equation solving problems. Write methods for solutions for:

Linear
Square

Each equation type is a class. Sometimes equations do not have real roots - in this case throw your exception and handle using try-catch-finally it.

2 numbers”. Brush up the code, handle exceptions correctly

and provide proper reactions (print) on situations:

file not found
other file issues
parsing numbers
arithmetic overflow

Equation add exceptions. Find best existing exception implementations for

these cases.

interface.
Randomly set up bombs
Handle bomb blast as exception.
Move

is made by typing coordinates (D4)
Handle incorrect inputs
Handle input for already processed cells

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