Question

有没有办法可以将3个函数中的一个fun1传递给fun3作为eval的参数然后进行评估？代码：

public class Pruebas {
    public static double fun1(double x){
        return x*1;
    }
    public static double fun2(double x){
        return x*2;
    }
    public static double fun3(double x){
        return x*3;
    }
    public static double eval(funx,double x0){
       /* funx at this point i expect it to be fun1, fun2 or fun3 */
       double f=funx(x0);
       return f;
    }
}

Answer 1

如果您能负担 Java 8

，则可以使用Method References

package javaapplication4;

import java.util.function.Function;

public class JavaApplication4 {

    public static class Pruebas 
    {
       public static double fun1(double x)
       {
           return x*1;
       }

       public static double fun2(double x){
           return x*2;
       }
       public static double fun3(double x){
           return x*3;
       }

       public static double eval(Function<Double, Double> fun,double x0)
       {
          double f=fun.apply(x0);
          return f;
       }
    }


    public static void main(String[] args) 
    {
        System.out.println(Pruebas.eval(Pruebas::fun3, 5));
    }

}

Answer 2

通常，这样做的方法是创建一个接口，然后有3个实现类。例如，

public interface FuncInterface
{
    public double func(double x);
}
public class Pruebas {
    public class Func1 implements FuncInterface {
        public static double func(double x){
           return x*1;
        }
    }
    public class Func2 implements FuncInterface {
        public static double func(double x){
           return x*2;
        }
    }
    public class Func3 implements FuncInterface {
        public static double func(double x){
           return x*3;
        }
    }
    public static double eval(FuncInterface funcI,double x0){
       /* funx at this point i expect it to be fun1, fun2 or fun3 */
       double f=funcI.func(x0);
       return f;
    }
}

从其他方法调用Java方法

2 个答案: