Herança e Composição/Exercício 02: Porta AND Ternária
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Problema
Defina uma nova classe que represente uma porta lógica AND com três entradas. Esta classe deve chamar-se AndGate3 e apresenta a mesma funcionalidade que a de duas entradas. A apresentação (toString) é A: valor B: valor C: valor.
A classe AndGate3 deve ser definida reutilizando o conceito AndGate2 (definido no Exercício 1).
Adapte a função main definida anteriormente, por forma a integrar alguns testes com a nova porta lógica.
Solution 1: AndGate3i defined as a subclass of AndGate2
In this solution we observe that the operation is a specialization of the previous one. This allows us to reuse the previous functionality.
| 'Ficheiro AndGate3i.java' |
|---|
/** Logical AND gate (inheritance). */
public class AndGate3i extends AndGate2 {
/** A new input is needed (the other two are inherited). */
private boolean _c = false;
/**
* Default constructor: false for all inputs.
*/
public AndGate3i() {
//super(); //default: explicit call not needed
}
/**
* Inputs receive same value.
*
* @param v
* the input value.
*/
public AndGate3i(boolean v) {
super(v);
_c = v;
}
/**
* Arbitrary input value combinations.
*
* @param a
* input value
* @param b
* input value
* @param c
* input value
*/
public AndGate3i(boolean a, boolean b, boolean c) {
super(a, b);
_c = c;
}
/**
* @return third input value.
*/
public boolean getC() {
return _c;
}
/**
* Set input value.
*
* @param c
* input value.
*/
public void setC(boolean c) {
_c = c;
}
/**
* @return value of logical AND operation.
*/
@Override
public boolean getOutput() {
return super.getOutput() && _c;
}
/**
* @see java.lang.Object#equals(java.lang.Object)
*/
@Override
public boolean equals(Object other) {
if (other instanceof AndGate3i) {
AndGate3i andGate = (AndGate3i) other;
return super.equals(other) && _c == andGate.getC();
}
return false;
}
/**
* @see java.lang.Object#toString()
*/
@Override
@SuppressWarnings("nls")
public String toString() {
return super.toString() + " C:" + _c;
}
}
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Solução 2: AndGate3c defined as a composition of two AndGate2
In this solution, the 3-input gate is defined as a composition of 2-input gates. Note that the A-input of the second gate is updated whenever the inputs of the first gate are changed.
| 'Ficheiro AndGate3c.java' |
|---|
| {{{2}}} |