(4 slides per page) - Updated

Overview
Phase 10
Introduction
Notations
Java
Implementation
of modules
Module Tests
Procedure
Example - TLC
Example - SBC
Phase 11
Phase 12
Summary
Overview
Phase 10
Introduction
Notations
Java
Implementation
of modules
Module Tests
Procedure
Example - TLC
Example - SBC
Phase 11
Phase 12
Summary
Interface Classes
A class where all methods are abstract can be declared as
an interface.
A class can implement several interfaces (keyword
implements), but it can only extend one other class.
A class can be accessed using the interface.
An interface class has no constructor.
Solves problem of multiple inheritance.
Exceptions
Methods can throw exceptions
public int div(int n1, int n2) throws Exception {
if (n2==0) throw Exception;
...
}
Exceptions can be handled with try and catch
try {
a = div(b,c);
} catch (Exception e) {
System.out.println(e);
}
Other exceptions are e.g. IOException,
ClassNotFoundException, ArithmeticException,
OutOfMemoryError, Error.
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Overview
Phase 10
Introduction
Notations
Java
Implementation
of modules
Module Tests
Procedure
Example - TLC
Example - SBC
Phase 11
Phase 12
Summary
Overview
Phase 10
Introduction
Notations
Java
Implementation
of modules
Module Tests
Procedure
Example - TLC
Example - SBC
Phase 11
Phase 12
Summary
Interface Classes: Example
animal
abstract makesound()
dog
cat
makesound() makesound()
Assertions
public interface Animal {
public void makeSound();
}
public class Cat implements Animal {
public Cat(){}
public void makeSound()
{System.out.println("miaow");}
}
public class Dog implements Animal {
public Dog(){}
public void makeSound()
{System.out.println("woof-woof");}
}
public class Main{
public static void main(String[] args) {
Animal a1 = new Dog();
Animal a2 = new Cat();
a1.makeSound(); a2.makeSound();
}
}
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Assertions can be used to specify (and check) the
pre-conditions of a method.
Assertions are defined using
assert condition==true: "ErrorString";
Assertions are introduced in Java 1.5, they are only
evaluated using the execution switch “evaluate assertions”:
java -ea
Exceptions thrown by assertions cannot be caught.
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