BigDecimal 和NumberFormat及 获取总页数的应用

1.

public class BigDecimalTest {
    public static  void add(double d1,double d2){
        BigDecimal b1 = new BigDecimal(d1);
        BigDecimal b2 = new BigDecimal(d2);
        double result = b1.add(b2).doubleValue();
        int result2 = b1.add(b2).intValue();
        System.out.println(result);
    }

    public static  void sub(double d1, double d2){
        BigDecimal b1 = new BigDecimal(d1);
        BigDecimal b2 = new BigDecimal(d2);
        double result = b1.subtract(b2).doubleValue();//7.2219999999999995
        System.out.println(result);
    }

    public static void multiply (double d1, double d2){
        BigDecimal b1 = new BigDecimal(d1);
        BigDecimal b2 = new BigDecimal(d2);
        double result = b1.multiply(b2).doubleValue();
        System.out.println(result);
    }

    public static void divide (double d1, double d2,int len){
        BigDecimal b1 = new BigDecimal(d1);
        BigDecimal b2 = new BigDecimal(d2);
        double result = b1.divide(b2,len,BigDecimal.ROUND_HALF_UP).doubleValue();//BigDecimal.ROUND_HALF_UP 四舍五入
        System.out.println(result);
    }

    private  static  void getTotalPages(double d1,double d2){
        BigDecimal b1 = new BigDecimal(d1);
        BigDecimal b2 = new BigDecimal(d2);
        int totalPage = b1.divide(b2,0,BigDecimal.ROUND_UP).intValue();//小数点后保留0位， 小数点位置非0加一
        System.out.println(totalPage);
    }

    public static void main(String[] args) {
        add(10.333,3.111);//13.444
        sub(10.333,3.111);//7.2219999999999995
        multiply(10.333,3.111);//32.145963
        divide(10.0,3.0,1);//3.3
        divide(10.0,3.0,2);//3.33, len代表小数点后面几位 BigDecimal.ROUND_HALF_UP
        divide(10.0,3.0,3);//3.333, len代表小数点后面几位
        divide(10.0,3.0,4);//3.3333
        getTotalPages(100,30);//总记录是100跳每页要有30条记录，总共多少页？ 4页！
    }
}

    public int getTotalPage() {
        if(perpage>0){
            BigDecimal b1 = new BigDecimal(totalCount);
            BigDecimal b2 = new BigDecimal(perpage);
            totalPage = b1.divide(b2,0,BigDecimal.ROUND_UP).intValue();
            return totalPage;
        }else{
            return 0;
        }
    }

 2. Bigdecimal 与 NumberFormat

public class NumberFormatDemo {

    public static void main(String[] args) {
        NumberFormat currency = NumberFormat.getCurrencyInstance();
        NumberFormat percent = NumberFormat.getPercentInstance();
        
        percent.setMinimumFractionDigits(2);//百分比后三位

        BigDecimal loanAmout = new BigDecimal("15000.8");
        BigDecimal interestRate = new BigDecimal("0.008");
        BigDecimal interest = loanAmout.multiply(interestRate);

        System.out.println("贷款金额：\t"+ currency.format(loanAmout));
        System.out.println("利率：\t"+percent.format(interestRate));
        System.out.println("利息：\t"+currency.format(interest));
    }
            /*
                贷款金额：	￥15,000.80
                利率：	0.80%
                利息：	￥120.01
            */
}