Java 等额本金计算工具类等额本金函数计算公式

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mob64ca1406d617 2023-10-15 21:20:33

文章标签 Java 等额本金计算工具类 ios 等额本息计算金额计算 ide 文章分类 Java 后端开发

ios理财类的app中很多涉及到等额本息的计算方式
然而等额本息的计算也是有两种方法的
因为涉及到金额的都是保留小数后两位的运算，但是，往往实际操作过程中的运算不止两位小数
这个时候我们是用NSDecimalNumber进行计算呢，还是用double进行计算呢

直接上代码了

/**
 等额本息收益计算
 *  公式： 每月本息还款额=(投资金额*月利率*(1+月利率)^还款月数)/(((1+月利率)^还款月数)-1)
 @param interest 年化收益
 @param investAmount 投资金额
 @param month 投资月份
 @param isMonth 是否是按月计算
 @param addrate 加息额度
 @param isAddlixi 是否是加息计算
 @return 收益或加息收益
 */
-(double)calculatePrincipalAndInterestBidWithInvestInterest:(double)interest
                                                     amount:(NSString *)investAmount AndMonth:(double )month AndStyle:(BOOL)isMonth AndAddRate:(double)addrate andBool:(BOOL)isAddlixi
{
    if ([investAmount isEqualToString:@""]) {
        investAmount = @"0";
    }
    NSDecimalNumberHandler *roundBanker = [NSDecimalNumberHandler decimalNumberHandlerWithRoundingMode:NSRoundBankers
                                                                                                 scale:2.0f
                                                                                      raiseOnExactness:NO
                                                                                       raiseOnOverflow:NO
                                                                                      raiseOnUnderflow:NO
                                                                                   raiseOnDivideByZero:YES];
    NSDecimalNumber *investAmountDec = [[NSDecimalNumber alloc] initWithString:investAmount];//投资金额
    NSDecimalNumber *monthInterestDec = [[NSDecimalNumber decimalNumberWithString:[NSString stringWithFormat:@"%f",interest/100]] decimalNumberByDividingBy:[NSDecimalNumber decimalNumberWithString:[NSString stringWithFormat:@"%f",12.00]]];//月利率
    NSDecimalNumber *nomonthInterestDec = [[NSDecimalNumber decimalNumberWithString:[NSString stringWithFormat:@"%f",(interest - addrate)/100]] decimalNumberByDividingBy:[NSDecimalNumber decimalNumberWithString:[NSString stringWithFormat:@"%f",12.00]]];//未加息月利率

    if (!isMonth) {
        //按天标,转化为月份
        month = month/30.00;
    }
    NSDecimalNumber *monthDec = [NSDecimalNumber decimalNumberWithString:[NSString stringWithFormat:@"%f",month]];//还款月数
    //    *  公式： 每月本息还款额=(投资金额*月利率*(1+月利率)^还款月数)/(((1+月利率)^还款月数)-1)

    NSDecimalNumber *decNum1 = [[[[[NSDecimalNumber decimalNumberWithString:[NSString stringWithFormat:@"%d",1]] decimalNumberByAdding:monthInterestDec] decimalNumberByRaisingToPower:month] decimalNumberByMultiplyingBy:monthInterestDec] decimalNumberByMultiplyingBy:investAmountDec];
    NSDecimalNumber *decNum2 = [[[[NSDecimalNumber decimalNumberWithString:[NSString stringWithFormat:@"%d",1]] decimalNumberByAdding:monthInterestDec] decimalNumberByRaisingToPower:month] decimalNumberBySubtracting:[NSDecimalNumber decimalNumberWithString:[NSString stringWithFormat:@"%d",1]]];
    NSDecimalNumber *monthIncomeDec = [decNum1 decimalNumberByDividingBy:decNum2];//月本息还款额
    //    每月利息 = 剩余本金x贷款月利率
    //        第一个月
    NSDecimalNumber *lixi = [investAmountDec decimalNumberByMultiplyingBy:monthInterestDec];
    NSDecimalNumber *noaddLixi = [investAmountDec decimalNumberByMultiplyingBy:nomonthInterestDec];

    NSString *benjin = [NSString decimalNumberCalucate:[NSString stringWithFormat:@"%.2f",monthIncomeDec.doubleValue] originValue2:[NSString stringWithFormat:@"%.2f",lixi.doubleValue] calucateWay:2];
//    NSDecimalNumber *leftBenjin = [investAmountDec decimalNumberBySubtracting:benjin];
    NSString  *leftBenjin = [NSString decimalNumberCalucate:[NSString stringWithFormat:@"%.2f",investAmountDec.doubleValue] originValue2:benjin calucateWay:2];

//    NSLog(@"利息%@本金%@剩余本金%@",lixi,benjin,leftBenjin);
//    NSLog(@"第一个月每月利息%.2f 年化收益 %.2f 每月利率 %@",lixi.doubleValue,interest,monthInterestDec);
//    NSLog(@"每个月本息%@",monthIncomeDec);
    NSString *allLixi = [NSString stringWithFormat:@"%.2f",lixi.doubleValue];
    NSString *addlixi = [NSString decimalNumberCalucate:[NSString stringWithFormat:@"%.2f",lixi.doubleValue] originValue2:[NSString stringWithFormat:@"%.2f",noaddLixi.doubleValue] calucateWay:2];
//    NSLog(@"lixica = %@ 第一个第一个利息 = %@ 第二个利息= %@",addlixi,lixi,noaddLixi);
    NSLog(@"------------------------");
    NSLog(@"本息:%@,本金:%@,利率:%@,利息:%.2f,未加息:%@,加息部分:%@",monthIncomeDec,benjin,monthInterestDec,lixi.doubleValue,noaddLixi,addlixi);
    if (month > 1) {
        for (int xx = 0 ; xx < month -1; xx ++) {
            //        第二个月
            double lixi111 = leftBenjin.doubleValue *monthInterestDec.doubleValue;
            double lixi222 = leftBenjin.doubleValue *nomonthInterestDec.doubleValue;

//            NSString *lixi111 = [NSString decimalNumberCalucate:leftBenjin originValue2:[NSString stringWithFormat:@"%f",monthInterestDec.doubleValue] calucateWay:3];
            NSString *benjin111 = [NSString decimalNumberCalucate:[NSString stringWithFormat:@"%.2f",monthIncomeDec.doubleValue] originValue2:[NSString stringWithFormat:@"%.2f",lixi111] calucateWay:2];
            NSString *leftBenjin111 = [NSString decimalNumberCalucate:leftBenjin originValue2:benjin111 calucateWay:2];
//            NSLog(@"每月利息%.2f ",lixi111.doubleValue);
            leftBenjin = leftBenjin111;
            double x = lixi111 - lixi222;
            NSString *lixica = [NSString decimalNumberCalucate:[NSString stringWithFormat:@"%.2f",lixi111] originValue2:[NSString stringWithFormat:@"%.2f",lixi222] calucateWay:2];
            addlixi = [NSString decimalNumberCalucate:addlixi originValue2:lixica calucateWay:1];
//            NSLog(@"lixica = %@ 第一个利息 = %.2f 第二个利息= %.2f",lixica,lixi111,lixi222);
//            NSLog(@"上次剩余本金%@每月利息%.2f这次本金%@这次剩余本金%@",leftBenjin,lixi111,benjin111,leftBenjin111);

            NSLog(@"本息:%@,本金:%@,利率:%@,利息:%.2f,未加息:%.2f,加息部分:%@",monthIncomeDec,benjin111,monthInterestDec,lixi111,lixi222,lixica);
            NSLog(@"x== %f********%@",x,addlixi);
            if (isAddlixi) {
                allLixi = addlixi;
            }else{
                allLixi = [NSString decimalNumberCalucate:allLixi originValue2:[NSString stringWithFormat:@"%.2f",lixi111] calucateWay:1];
            }
        }
    }
//    NSLog(@"alllixi = %@",allLixi);
//    NSDecimalNumber *totalIncomeDec = [[monthDec decimalNumberByMultiplyingBy:monthIncomeDec] decimalNumberBySubtracting:investAmountDec withBehavior:roundBanker];//总还款额 - 本金 = 总收益
    return [allLixi doubleValue] > 0 ? [allLixi doubleValue] : 0;
//    return [totalIncomeDec doubleValue] > 0 ? [totalIncomeDec doubleValue] : 0;
}

NSDecimalNumber计算方法

+ (NSString *)decimalNumberCalucate:(NSString *)originValue1 originValue2:(NSString *)originValue2 calucateWay:(NSInteger)calucateWay
{
    NSDecimalNumberHandler *numUp = [NSDecimalNumberHandler decimalNumberHandlerWithRoundingMode:NSRoundDown scale:2 raiseOnExactness:NO raiseOnOverflow:NO raiseOnUnderflow:NO raiseOnDivideByZero:YES];
    NSDecimalNumber *decimalNumber1 = [NSDecimalNumber decimalNumberWithString:originValue1];
    NSDecimalNumber *decimalNumber2 = [NSDecimalNumber decimalNumberWithString:originValue2];
    NSDecimalNumber *product;
    switch (calucateWay) {
        case 1://+
            product = [decimalNumber1 decimalNumberByAdding:decimalNumber2 withBehavior:numUp];
            break;

        case 2://-
            product = [decimalNumber1 decimalNumberBySubtracting:decimalNumber2 withBehavior:numUp];
            break;

        case 3://*
            product = [decimalNumber1 decimalNumberByMultiplyingBy:decimalNumber2 withBehavior:numUp];
            break;

        case 4:// /
            product = [decimalNumber1 decimalNumberByDividingBy:decimalNumber2 withBehavior:numUp];
            break;

        default:
            break;
    }

    return [product stringValue];
}

因为要计算每个月的本息，所以，在得到每月本息之后所有涉及到本息的计算过程中，都是需要使用两位小数进行，从而得出每月的剩余本金进行接下来的计算

很多理财产品涉及到的加息情况上面也有运算，加息部分不能用加息后的总利息和加息钱的总利息差进行计算，因为在运算过程中，剩余本金是不同的，所以计算每月加息差额之后进行总加息计算

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