java等额本息、等额本金计算（用了好久才知道等额本息原来这样算，记录一下）

public static void main(String[] args) {
        double invest = 280000;
        double yearRate = 0.0655;
        double monthRate = yearRate/12;
        int year = 15;
        int month = year * 12;
        // 每月本息金额  = (本金×月利率×(1＋月利率)＾还款月数)÷ ((1＋月利率)＾还款月数-1)
        double monthIncome = (invest* monthRate * Math.pow(1+monthRate,month))
/(Math.pow(1+monthRate,month)-1);
        System.out.println("每月本息金额 : "+ monthIncome);

// 每月本金 = 本金×月利率×(1+月利率)^(还款月序号-1)÷((1+月利率)^还款月数-1)
        double monthCapital = 0;
        for(inti=1;i1;i++){
                monthCapital = (invest* monthRate * (Math.pow((1+monthRate),i-1)))
/(Math.pow(1+monthRate,month)-1);
                System.out.println("第"+ i + "月本金： "+ monthCapital);
        }

// 每月利息  = 剩余本金 x 贷款月利率
        double monthInterest = 0;
        double capital = invest; double sumAvg = 0;
        double tmpCapital = 0;
            for(inti=1;i1;i++){
                    capital = capital - tmpCapital;
                    monthInterest = capital * monthRate;
                    tmpCapital = (invest* monthRate * (Math.pow((1+monthRate),i-1)))
/(Math.pow(1+monthRate,month)-1);
                    System.out.println("第"+ i + "月利息： "+ monthInterest);
                    sumAvg += monthInterest
            }
System.out.println
("总利息： "+ sumAvg); DecimalFormat decimalFormat = new DecimalFormat("0.00");
System.out.println
("总利息输出两位小数： "+ Double.parseDouble(decimalFormat.format(sumAvg)));

}