Java 舍入( double )

Question

double y1 = 0;  
double y2 = 0;  
double i = 0.025;  
double n = 2;  
double h1 = 2000; 
double h2 = 4000; 

y1 = Math.pow((1 + i), n) * h1;
y2 = Math.pow((1 + i), n) * h2;
double result =  y1 + y2;
System.out.println(result);

我希望结果为“6303.749999999999”，但它给了我“6303.75”。我该如何解决？

Answer 1

正确的结果应该是(而且确实是) 6303.750000000000017069679003611781820568916563219777423023367655509563911228609889292329171439632773399353027343750000

尝试看一下 BigDecimal 类。

    BigDecimal i = new BigDecimal(0.025);
    int n = 2;
    BigDecimal h1 = new BigDecimal(2000);
    BigDecimal h2 = new BigDecimal(4000);

    BigDecimal y1 = ((BigDecimal.ONE.add(i)).pow(n)).multiply(h1);
    BigDecimal y2 = ((BigDecimal.ONE.add(i)).pow(n)).multiply(h2);
    BigDecimal result =  y1.add(y2);

    System.out.println(result.toEngineeringString());