Difference between revisions of "Composite (padrão de desenho)/Exercício 1: Verificador"

From Wiki**3

< Composite (padrão de desenho)
(→‎Problema)
Line 9: Line 9:
 
String s2 = "oo";
 
String s2 = "oo";
 
String s3 = "xyz";
 
String s3 = "xyz";
−
Verifier v = new Or(new And(new LengthGreaterThan(5), new LengthLesserThan(8)), new LengthEqualTo(2));
+
Validator v = new Or(new And(new LengthGreaterThan(5), new LengthLesserThan(8)), new LengthEqualTo(2));
 
boolean b1 = v.ok(s1); // true
 
boolean b1 = v.ok(s1); // true
 
boolean b2 = v.ok(s2); // true
 
boolean b2 = v.ok(s2); // true
Line 16: Line 16:
  
 
= Solução =
 
= Solução =
 +
 +
== Classe Validator ==
 +
 +
<java5>
 +
/**
 +
* Abstract validator class.
 +
*/
 +
public abstract class Validator {
 +
/**
 +
* @param string
 +
* @return true if the string is valid according to some criterion; false
 +
*        otherwise.
 +
*/
 +
public abstract boolean ok(String string);
 +
}
 +
</java5>
 +
 +
== Classe UnaryOperator ==
 +
 +
<java5>
 +
/**
 +
* A simple unary operator.
 +
*/
 +
public abstract class UnaryOperator extends Validator {
 +
 +
/**
 +
* The argument.
 +
*/
 +
protected Validator _validator;
 +
 +
/**
 +
* @param validator
 +
*/
 +
public UnaryOperator(Validator validator) {
 +
_validator = validator;
 +
}
 +
 +
}
 +
</java5>
 +
 +
== Classe Not ==
 +
 +
<java5>
 +
/**
 +
* Negation operator.
 +
*/
 +
public class Not extends UnaryOperator {
 +
 +
/**
 +
* @param validator
 +
*/
 +
public Not(Validator validator) {
 +
super(validator);
 +
}
 +
 +
/**
 +
* @see Validator#ok(java.lang.String)
 +
*/
 +
@Override
 +
public boolean ok(String string) {
 +
return !_validator.ok(string);
 +
}
 +
 +
}
 +
</java5>
 +
 +
== Classe BinaryOperator ==
 +
 +
<java5>
 +
/**
 +
* A simple binary operator.
 +
*/
 +
public abstract class BinaryOperator extends Validator {
 +
 +
/**
 +
* The 1st argument.
 +
*/
 +
protected Validator _first;
 +
 +
/**
 +
* The 2nd argument.
 +
*/
 +
protected Validator _second;
 +
 +
/**
 +
* @param first
 +
* @param second
 +
*/
 +
public BinaryOperator(Validator first, Validator second) {
 +
_first = first;
 +
_second = second;
 +
}
 +
 +
}
 +
</java5>
 +
 +
== Classe And ==
 +
 +
<java5>
 +
/**
 +
* AND operation.
 +
*/
 +
public class And extends BinaryOperator {
 +
 +
/**
 +
* @param first
 +
* @param second
 +
*/
 +
public And(Validator first, Validator second) {
 +
super(first, second);
 +
}
 +
 +
/**
 +
* @see Validator#ok(java.lang.String)
 +
*/
 +
@Override
 +
public boolean ok(String string) {
 +
return _first.ok(string) && _second.ok(string);
 +
}
 +
 +
}
 +
</java5>
 +
 +
== Classe Or ==
 +
 +
<java5>
 +
/**
 +
* AND operation.
 +
*/
 +
public class Or extends BinaryOperator {
 +
 +
/**
 +
* @param first
 +
* @param second
 +
*/
 +
public Or(Validator first, Validator second) {
 +
super(first, second);
 +
}
 +
 +
/**
 +
* @see Validator#ok(java.lang.String)
 +
*/
 +
@Override
 +
public boolean ok(String string) {
 +
return _first.ok(string) || _second.ok(string);
 +
}
 +
 +
}
 +
</java5>
 +
 +
== Classe IntegerComparisonOperator ==
 +
 +
<java5>
 +
/**
 +
* Compare some integer value with a reference.
 +
*/
 +
public abstract class IntegerComparisonOperator extends Validator {
 +
 +
/**
 +
* The reference (an integer).
 +
*/
 +
protected int _reference;
 +
 +
/**
 +
* @param reference
 +
*/
 +
public IntegerComparisonOperator(int reference) {
 +
_reference = reference;
 +
}
 +
}
 +
</java5>
 +
 +
== Classe LengthGreaterThan ==
 +
 +
<java5>
 +
/**
 +
* Return true if string length is lesser than the reference.
 +
*/
 +
public class LengthGreaterThan extends IntegerComparisonOperator {
 +
 +
/**
 +
* @param reference
 +
*/
 +
public LengthGreaterThan(int reference) {
 +
super(reference);
 +
}
 +
 +
/**
 +
* @see Validator#ok(java.lang.String)
 +
*/
 +
@Override
 +
public boolean ok(String string) {
 +
return string.length() > _reference;
 +
}
 +
 +
}
 +
</java5>
 +
 +
== Classe LengthLesserThan ==
 +
 +
<java5>
 +
/**
 +
* Return true if string length is greater than reference.
 +
*/
 +
public class LengthLesserThan extends IntegerComparisonOperator {
 +
 +
/**
 +
* @param reference
 +
*/
 +
public LengthLesserThan(int reference) {
 +
super(reference);
 +
}
 +
 +
/**
 +
* @see Validator#ok(java.lang.String)
 +
*/
 +
@Override
 +
public boolean ok(String string) {
 +
return string.length() < _reference;
 +
}
 +
 +
}
 +
</java5>
 +
 +
== Classe LengthEqualTo ==
 +
 +
<java5>
 +
/**
 +
* Return true if string length is equal to the reference.
 +
*/
 +
public class LengthEqualTo extends IntegerComparisonOperator {
 +
 +
/**
 +
* @param reference
 +
*/
 +
public LengthEqualTo(int reference) {
 +
super(reference);
 +
}
 +
 +
/**
 +
* @see Validator#ok(java.lang.String)
 +
*/
 +
@Override
 +
public boolean ok(String string) {
 +
return string.length() == _reference;
 +
}
 +
 +
}
 +
</java5>
 +
 +
== Classe LengthIsEven ==
 +
 +
<java5>
 +
/**
 +
* True for non-empty strings.
 +
*/
 +
public class LengthIsEven extends Validator {
 +
 +
/**
 +
* @see Validator#ok(java.lang.String)
 +
*/
 +
@Override
 +
public boolean ok(String string) {
 +
return string.length() % 2 != 0;
 +
}
 +
 +
}
 +
</java5>
 +
 +
== Classe LengthIsOdd ==
 +
 +
<java5>
 +
/**
 +
* True for non-empty strings.
 +
*/
 +
public class LengthIsOdd extends Validator {
 +
 +
/**
 +
* @see Validator#ok(java.lang.String)
 +
*/
 +
@Override
 +
public boolean ok(String string) {
 +
return string.length() % 2 == 0;
 +
}
 +
 +
}
 +
</java5>
 +
 +
== Classe NonZeroLength ==
 +
 +
<java5>
 +
/**
 +
* True for non-empty strings.
 +
*/
 +
public class NonZeroLength extends Validator {
 +
 +
/**
 +
* @see Validator#ok(java.lang.String)
 +
*/
 +
@Override
 +
public boolean ok(String string) {
 +
return string.length() != 0;
 +
}
 +
 +
}
 +
</java5>
 +
 +
== Classe App ==
 +
 +
<java5>
 +
/**
 +
* A simple application.
 +
*/
 +
public class App {
 +
 +
/**
 +
* @param args
 +
*/
 +
public static void main(String[] args) {
 +
String s1 = "batata";
 +
String s2 = "oo";
 +
String s3 = "xyz";
 +
Validator v = new Or(new And(new LengthGreaterThan(5),
 +
new LengthLesserThan(8)), new LengthEqualTo(2));
 +
boolean b1 = v.ok(s1); // true
 +
boolean b2 = v.ok(s2); // true
 +
boolean b3 = v.ok(s3); // false
 +
System.out.println("b1=" + b1 + " b2=" + b2 + " b3=" + b3);
 +
}
 +
 +
}
 +
</java5>
 +
 +
= Compilação e Execução =
 +
 +
== Compilação ==
 +
 +
== Execução ==
 +
 +
java App
 +
 +
Resultado:
 +
 +
b1=true b2=true b3=false
  
 
[[category:PO]]
 
[[category:PO]]
 
[[category:Ensino]]
 
[[category:Ensino]]

Revision as of 04:15, 9 November 2009

Problema

Os elementos de uma colecção de nomes (String) têm um conjunto de propriedades a verificar. Para tal, foi criado um verificador automático que faz uso de avaliadores booleanos representados por objectos. Cada avaliador booleano tem uma função ok que aceita uma String e devolve um valor booleano. Implemente os seguintes predicados e operadores: NonZeroLength, LengthIsEven, LengthIsOdd, LengthGreaterThan, LengthLesserThan, LengthEqualTo, And (operador binário que é verdadeiro quando dois elementos são verdadeiros), Or (operador binário que é falso quando dois elementos são falsos), Not (operador unário que é verdadeiro quando o seu argumento é falso).

Exemplo:

<java5> String s1 = "batata"; String s2 = "oo"; String s3 = "xyz"; Validator v = new Or(new And(new LengthGreaterThan(5), new LengthLesserThan(8)), new LengthEqualTo(2)); boolean b1 = v.ok(s1); // true boolean b2 = v.ok(s2); // true boolean b3 = v.ok(s3); // false </java5>

Solução

Classe Validator

<java5> /** 

* Abstract validator class.
*/

public abstract class Validator { /** * @param string * @return true if the string is valid according to some criterion; false * otherwise. */ public abstract boolean ok(String string); } </java5>

Classe UnaryOperator

<java5> /** 

* A simple unary operator.
*/

public abstract class UnaryOperator extends Validator {

/** * The argument. */ protected Validator _validator;

/** * @param validator */ public UnaryOperator(Validator validator) { _validator = validator; }

} </java5>

Classe Not

<java5> /** 

* Negation operator.
*/

public class Not extends UnaryOperator {

/** * @param validator */ public Not(Validator validator) { super(validator); }

/** * @see Validator#ok(java.lang.String) */ @Override public boolean ok(String string) { return !_validator.ok(string); }

} </java5>

Classe BinaryOperator

<java5> /** 

* A simple binary operator.
*/

public abstract class BinaryOperator extends Validator {

/** * The 1st argument. */ protected Validator _first;

/** * The 2nd argument. */ protected Validator _second;

/** * @param first * @param second */ public BinaryOperator(Validator first, Validator second) { _first = first; _second = second; }

} </java5>

Classe And

<java5> /** 

* AND operation.
*/

public class And extends BinaryOperator {

/** * @param first * @param second */ public And(Validator first, Validator second) { super(first, second); }

/** * @see Validator#ok(java.lang.String) */ @Override public boolean ok(String string) { return _first.ok(string) && _second.ok(string); }

} </java5>

Classe Or

<java5> /** 

* AND operation.
*/

public class Or extends BinaryOperator {

/** * @param first * @param second */ public Or(Validator first, Validator second) { super(first, second); }

/** * @see Validator#ok(java.lang.String) */ @Override public boolean ok(String string) { return _first.ok(string) || _second.ok(string); }

} </java5>

Classe IntegerComparisonOperator

<java5> /** 

* Compare some integer value with a reference.
*/

public abstract class IntegerComparisonOperator extends Validator {

/** * The reference (an integer). */ protected int _reference;

/** * @param reference */ public IntegerComparisonOperator(int reference) { _reference = reference; } } </java5>

Classe LengthGreaterThan

<java5> /** 

* Return true if string length is lesser than the reference.
*/

public class LengthGreaterThan extends IntegerComparisonOperator {

/** * @param reference */ public LengthGreaterThan(int reference) { super(reference); }

/** * @see Validator#ok(java.lang.String) */ @Override public boolean ok(String string) { return string.length() > _reference; }

} </java5>

Classe LengthLesserThan

<java5> /** 

* Return true if string length is greater than reference.
*/

public class LengthLesserThan extends IntegerComparisonOperator {

/** * @param reference */ public LengthLesserThan(int reference) { super(reference); }

/** * @see Validator#ok(java.lang.String) */ @Override public boolean ok(String string) { return string.length() < _reference; }

} </java5>

Classe LengthEqualTo

<java5> /** 

* Return true if string length is equal to the reference.
*/

public class LengthEqualTo extends IntegerComparisonOperator {

/** * @param reference */ public LengthEqualTo(int reference) { super(reference); }

/** * @see Validator#ok(java.lang.String) */ @Override public boolean ok(String string) { return string.length() == _reference; }

} </java5>

Classe LengthIsEven

<java5> /** 

* True for non-empty strings.
*/

public class LengthIsEven extends Validator {

/** * @see Validator#ok(java.lang.String) */ @Override public boolean ok(String string) { return string.length() % 2 != 0; }

} </java5>

Classe LengthIsOdd

<java5> /** 

* True for non-empty strings.
*/

public class LengthIsOdd extends Validator {

/** * @see Validator#ok(java.lang.String) */ @Override public boolean ok(String string) { return string.length() % 2 == 0; }

} </java5>

Classe NonZeroLength

<java5> /** 

* True for non-empty strings.
*/

public class NonZeroLength extends Validator {

/** * @see Validator#ok(java.lang.String) */ @Override public boolean ok(String string) { return string.length() != 0; }

} </java5>

Classe App

<java5> /** 

* A simple application.
*/

public class App {

/** * @param args */ public static void main(String[] args) { String s1 = "batata"; String s2 = "oo"; String s3 = "xyz"; Validator v = new Or(new And(new LengthGreaterThan(5), new LengthLesserThan(8)), new LengthEqualTo(2)); boolean b1 = v.ok(s1); // true boolean b2 = v.ok(s2); // true boolean b3 = v.ok(s3); // false System.out.println("b1=" + b1 + " b2=" + b2 + " b3=" + b3); }

} </java5>

Compilação e Execução

Compilação

Execução

java App

Resultado: 

b1=true b2=true b3=false
Retrieved from "https://web.tecnico.ulisboa.pt/~david.matos/w/pt/index.php?title=Composite_(padrão_de_desenho)/Exercício_1:_Verificador&oldid=3408"