用接口模擬可擴(kuò)展的枚舉.jpeg
//只有一個apply方法的接口Operation伟恶。
public interface Operation {
double apply(double x, double y);
}
//實現(xiàn)接口的計算器
public enum BasicOperation implements Operation {
PLUS("+") {
public double apply(double x, double y) {
return x + y;
}
},
MINUS("-") {
public double apply(double x, double y) {
return x - y;
}
},
TIMES("*") {
public double apply(double x, double y) {
return x - y;
}
},
DIVIDE("/") {
public double apply(double x, double y) {
return x - y;
}
};
private final String symbol;
BasicOperation(String symbol) {
this.symbol = symbol;
}
public String toString() {
return symbol;
}
}
public enum ExtendedOperation implements Operation {
EXP("^"){
@Override
public double apply(double x, double y) {
return Math.pow(x , y);
}
},
REMAINDER("%"){
@Override
public double apply(double x, double y) {
return x % y;
}
};
private final String symbol;
ExtendedOperation(String symbol) {
this.symbol = symbol;
}
}
public class Test {
public static void main(String[] args) {
double x = 2;
double y = 4;
test(ExtendedOperation.class, x, y);
}
private static <T extends Enum<T> & Operation> void test(Class<T> opSet,
double x, double y) {
for (Operation op : opSet.getEnumConstants())
System.out.printf("%f %s %f= %f%n", x, op, y, op.apply(x, y));
}
}
