相关疑难解决方法(0)

似乎减法正在触发某种问题,结果值是错误的.

double tempCommission = targetPremium.doubleValue()*rate.doubleValue()/100d;

78.75 = 787.5*10.0/100d

double netToCompany = targetPremium.doubleValue() - tempCommission;

708.75 = 787.5 - 78.75

double dCommission = request.getPremium().doubleValue() - netToCompany;

877.8499999999999 = 1586.6 - 708.75

由此产生的预期值为877.85.

应该怎样做才能确保正确计算？

import java.awt.Rectangle;
import java.util.Comparator;
public class RectangleComparator implements Comparator
{
      public int compare(Object object1, Object object2)
      {
        Rectangle rec1 = (Rectangle) object1;
        Rectangle rec2 = (Rectangle) object2;

        return rec1.getWidth().compareTo(rec2.getWidth());
    }
}

出于某种原因,我得到的错误是双倍无法解除引用.任何人都可以帮我找出原因吗？

 public static void main(String[] args) {
     double [] boxes;
        boxes = new double[]  {20, 10, 5, 40, 20, 41, 41, 2, 6, 7, 3, 4, 5, 6, 23, 34, 7, 8, 2, 2};
        double heaviest = 0;
        double normal = 0;
        double heavy = 0;
        double totalCost;
        double a = 0;
        double b = 0;
        int repeatCount=0;

        for (int i = 1; i < boxes.length; i++) {
            if (boxes[i] > heaviest)
                heaviest = boxes[i];
        }

        for(double element: boxes) {
            if(element==heaviest) …

我有两个双重值.我想检查两个double值是否相同.我有两种比较这个双值的方法.

第一种方式:

double a = 0.1;
double b = 0.2;
if(a == b) {
    System.out.println("Double values are same");
}

另一种比较方式:

if(Double.compare(a, b) == 0) {
    System.out.println("Double values are same");
}

哪一种最好的方法又准确？比较双值是否两种方式相同？

所以我几乎完全理解方法,对象和OOP.然而,我正在为初学者准备一本德语Java编程书,我必须创建一个提款限额高达-1000欧元的银行账户.不知何故,即使金额为-1000欧元,代码也会执行else代码,这对我来说毫无意义.它不应该在我看来输出错误,但确实如此.

这是帐户代码:

public class Account {
  private String accountnumber;
  protected double accountbalance;

Account(String an, double ab) {
  accountnumber = an;
  accountbalance = ab;  
}

double getAccountbalance() {
  return accountbalance;
}

String getAccountnumber() { 
  return accountnumber;
}


void deposit(double ammount) {
  accountbalance += ammount;
}

void withdraw(double ammount) {
  accountbalance -= ammount;
}

}

扩展帐户:

public class GiroAccount extends Account{

double limit;

GiroAccount(String an, double as, double l) {
  super(an, as);
  limit = l;
}

double getLimit() {
  return limit;

} …