如果我贷款买一套 400W 的房子，我要给银行多送几辆迈巴赫？

2023 年至今，上海房价一跌再跌。俺已经蠢蠢欲动了，磨刀霍霍向"买房"。但是奈何手里钞票不够，只能向天再借 500 年打工赚钱。但是作为倔强的互联网打工人，想知道自己会被银行割多少韭菜。于是就写了个程序，用于计算我贷款买房需要多给银行还多少钱。这样我就能知道银行割我的韭菜，能省下几辆迈巴赫的钱了。

贷款利率

• 公积金的贷款利率。
  • 首房：贷款时间 <=5 年，利率为 2.6%；贷款时间 >= 5 年，利率为 3.1%。
  • 非首房：贷款时间 <=5 年，利率为 3.025%；贷款时间 >= 5 年，利率为 3.575%。

• 商业险贷款利率

  • 贷款时间 <=5 年，利率为 3.45%；贷款时间 >= 5 年，利率为 3.95%。

代码实现

• 以下代码，实现了：我贷款买房需要多给银行还多少钱。

public class LoanAmountCalculation {

    //首套住房5年以内公积金贷款利率
    private static final double FIRST_HOUSE_ACCUMULATION_FUND_LOAN_RATE_WITHIN_FIVE_YEARS = 2.6;
    //首套住房5年以上公积金款利率
    private static final double FIRST_HOUSE_ACCUMULATION_FUND_LOAN_RATE_MORE_FIVE_YEARS = 3.1;
    //二房5年以内公积金贷款利率
    private static final double NOT_FIRST_HOUSE_ACCUMULATION_FUND_LOAN_RATE_WITHIN_FIVE_YEARS = 3.025;
    //二房5年以上公积金款利率
    private static final double NOT_FIRST_HOUSE_ACCUMULATION_FUND_LOAN_RATE_MORE_FIVE_YEARS = 3.575;
    //5年以内商业贷款利率
    private static final double COMMERCIAL_LOAN_RATE_WITHIN_FIVE_YEARS = 3.45;
    //5年以上商业贷款利率
    private static final double COMMERCIAL_LOAN_RATE_MORE_FIVE_YEARS = 3.95;

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        double houseAmount = getInputValue(scanner, "请输入预计买房金额(单位:W)：", "请输出正确的买房金额（>0）！");
        double principal = getInputValue(scanner, "请输入您的本金(单位:W)：", "请输出正确的买房金额（>0）！");
        if (principal >= houseAmount) {
            System.out.println("全款买房，崇拜大佬！");
            return;
        }

        double accumulationFundLoanAmount = getInputValue(scanner, "请输入公积金贷款金额(单位:W)：", "请输出正确的公积金贷款金额（>0）！");

        double commercialLoanAmount = houseAmount - principal - accumulationFundLoanAmount;
        if(commercialLoanAmount <= 0){
            System.out.println("您的本金+公积金贷款已经够买房啦，恭喜大佬！");
            return;
        }else{
            System.out.println("您的本金+公积金贷款还不够买房哦，需要商业贷款金额为(单位:W)：" + commercialLoanAmount + "\n");
        }

        int accumulationFundLoanYears = getInputIntValue(scanner, "请输入公积金贷款年份(单位:年)：");
        int commercialLoanAmountYears = getInputIntValue(scanner, "请输入商业贷款年份(单位:年)：");

        int isFirstHouse = getInputIntValue(scanner, "请输入是否首房(0:否，1：是)：");

        LoanAmount loanAmount = calculateLoanAmount(
                accumulationFundLoanAmount, accumulationFundLoanYears,
                commercialLoanAmount, commercialLoanAmountYears, isFirstHouse);
        System.out.println("详细贷款信息如下：" + "\n" + loanAmount);
    }

    /**
     * 获取double类型的输入
     * @param scanner：Java输入类
     * @param prompt：提示信息
     * @param errorMessage：输入错误的提示信息
     * @return 一个double类型的输入
     */
    private static double getInputValue(Scanner scanner, String prompt, String errorMessage) {
        double value;
        while (true) {
            System.out.println(prompt);
            if (scanner.hasNextDouble()) {
                value = scanner.nextDouble();
                if (value > 0) {
                    break;
                } else {
                    System.out.println(errorMessage);
                }
            } else {
                scanner.next();
                System.out.println(errorMessage);
            }
        }
        return value;
    }

    /**
     * 获取int类型的输入
     * @param scanner：Java输入类
     * @param prompt：提示信息
     * @return 一个int类型的输入
     */
    private static int getInputIntValue(Scanner scanner, String prompt) {
        int value;
        while (true) {
            System.out.println(prompt);
            if (scanner.hasNextInt()) {
                value = scanner.nextInt();
                if (value > 0) {
                    break;
                } else {
                    System.out.println("请输入正确的年份（>0）！");
                }
            } else {
                scanner.next();
                System.out.println("请输入正确的年份（>0）！");
            }
        }
        return value;
    }

    /**
     * 功能：贷款金额计算
     * 入参：
     * 1.accumulationFundLoanAmount：公积金贷款金额  2.accumulationFundLoanYears：公积金贷款年份；
     * 3.commercialLoanAmount：商业贷款金额；        4.commercialLoanAmountYears：商业贷款年份
     * 5.isFirstHouse：是否首房
     */
    private static LoanAmount calculateLoanAmount(double accumulationFundLoanAmount, int accumulationFundLoanYears,
                                                           double commercialLoanAmount, int commercialLoanAmountYears, int isFirstHouse){
        LoanAmount loanAmount = new LoanAmount();
        //公积金贷款还款金额
        double accumulationFundRepaymentAmount;
        if(isFirstHouse == 1){
            accumulationFundRepaymentAmount = accumulationFundLoanYears <= 5 ?
                    accumulationFundLoanAmount * Math.pow((100 + FIRST_HOUSE_ACCUMULATION_FUND_LOAN_RATE_WITHIN_FIVE_YEARS) / 100, accumulationFundLoanYears)
                    : accumulationFundLoanAmount * Math.pow((100 + FIRST_HOUSE_ACCUMULATION_FUND_LOAN_RATE_MORE_FIVE_YEARS) / 100, accumulationFundLoanYears);
        }else{
            accumulationFundRepaymentAmount = accumulationFundLoanYears <= 5 ?
                    accumulationFundLoanAmount * Math.pow((100 + NOT_FIRST_HOUSE_ACCUMULATION_FUND_LOAN_RATE_WITHIN_FIVE_YEARS) / 100, accumulationFundLoanYears)
                    : accumulationFundLoanAmount * Math.pow((100 + NOT_FIRST_HOUSE_ACCUMULATION_FUND_LOAN_RATE_MORE_FIVE_YEARS) / 100, accumulationFundLoanYears);
        }
        loanAmount.setAccumulationFundRepaymentAmount(String.format("%.2f", accumulationFundRepaymentAmount));

        //公积金贷款每年还款金额
        loanAmount.setAccumulationFundAnnualRepaymentAmount(String.format("%.2f", accumulationFundRepaymentAmount / accumulationFundLoanYears));

        //商业贷款还款金额
        double commercialRepaymentAmount = commercialLoanAmountYears <= 5 ?
                commercialLoanAmount * Math.pow((100 + COMMERCIAL_LOAN_RATE_WITHIN_FIVE_YEARS) / 100, commercialLoanAmountYears)
                : commercialLoanAmount * Math.pow((100 + COMMERCIAL_LOAN_RATE_MORE_FIVE_YEARS) / 100, commercialLoanAmountYears);
        loanAmount.setCommercialRepaymentAmount(String.format("%.2f", commercialRepaymentAmount));

        //商业贷款每年还款金额
        loanAmount.setCommercialAnnualRepaymentAmount(String.format("%.2f", commercialRepaymentAmount / commercialLoanAmountYears));

        //公积金贷款超出金额
        loanAmount.setAccumulationFundLoanExceedAmount(String.format("%.2f", accumulationFundRepaymentAmount - accumulationFundLoanAmount));

        //商业贷款超出金额
        loanAmount.setCommercialLoanExceedAmount(String.format("%.2f", commercialRepaymentAmount - commercialLoanAmount));

        loanAmount.setTotalExceedLoanAmount(String.format("%.2f", accumulationFundRepaymentAmount - accumulationFundLoanAmount + commercialRepaymentAmount - commercialLoanAmount));
        return loanAmount;
    }
    @Data
    static class LoanAmount{
        /**
         * 公积金贷款还款金额
         */
        private String accumulationFundRepaymentAmount;
        /**
         * 公积金贷款每年还款金额
         */
        private String accumulationFundAnnualRepaymentAmount;
        /**
         * 商业贷款还款金额
         */
        private String commercialRepaymentAmount;
        /**
         * 商业贷款每年还款金额
         */
        private String commercialAnnualRepaymentAmount;
        /**
         * 公积金贷款超出金额 = 公积金贷款还款金额 - 公积金贷款金额
         */
        private String accumulationFundLoanExceedAmount;
        /**
         * 商业贷款超出金额 = 商业贷款还款金额 - 商业贷款金额
         */
        private String commercialLoanExceedAmount;

        /**
         * 总共贷款超出金额
         */
        private String totalExceedLoanAmount;

        @Override
        public String toString() {
            return "1.公积金贷款还款金额=" + accumulationFundRepaymentAmount + "万元\n" +
                    "2.商业贷款还款金额=" + commercialRepaymentAmount + "万元\n" +
                    "3.公积金贷款每年还款金额=" + accumulationFundAnnualRepaymentAmount + "万元\n" +
                    "4.商业贷款每年还款金额=" + commercialAnnualRepaymentAmount + "万元\n" +
                    "5.公积金贷款超出金额=" + accumulationFundLoanExceedAmount + "万元\n" +
                    "6.商业贷款超出金额=" + commercialLoanExceedAmount + "万元\n" +
                    "7.总共贷款超出金额=" + totalExceedLoanAmount + "万元\n";
        }
    }
}

• 代码输入，输出示例：

由上图可知，我要贷款买一套 400w 的房子，本金只有 120w，使用组合贷：公积金贷款 120w（10年），商业贷款 160w（20年）。最终我需要多还银行 230.07w，相当于买两辆迈巴赫的钱了，巨亏！

以上就是全部内容了，如果涉及到真实场景，还是需要根据具体的情况计算的！