java 銀行貸款工具類

等額本金

 /**
     * 計算等額本金還款
     *
     * @param principal 貸款總額
     * @param months    貸款期限
     * @param rate      貸款利率
     * @return
     */
    public static Kv calculateEqualPrincipal(double principal, int months, double rate) {
        Kv kv = Kv.create();
        double monthRate = rate / (100 * 12);//月利率
        double prePrincipal = principal / months;//每月還款本金
        double firstMonth = prePrincipal + principal * monthRate;//第一個月還款金額
        double decreaseMonth = prePrincipal * monthRate;//每月利息遞減
        double interest = (months + 1) * principal * monthRate / 2;//還款總利息
        double totalMoney = principal + interest;//還款總額
        kv.put("totalMoney",format(totalMoney));//還款總額
        kv.put("principal",format(principal));//貸款總額
        kv.put("interest",format(interest));//還款總利息
        kv.put("firstMonth",format(firstMonth*10000));//首月還款金額
        kv.put("decreaseMonth",format(decreaseMonth*10000));//每月遞減利息
        kv.put("months",months);//還款期限
        return kv;
    }

等額本金

 /**
     * 計算等額本息還款
     *
     * @param principal 貸款總額
     * @param months    貸款期限
     * @param rate      貸款利率
     * @return
     */
    public static Kv calculateEqualPrincipalAndInterest(double principal, int months, double rate) {
        Kv kv = Kv.create();
        double monthRate = rate / (100 * 12);//月利率
        double preLoan = (principal * monthRate * Math.pow((1 + monthRate), months)) / (Math.pow((1 + monthRate), months) - 1);//每月還款金額
        double totalMoney = preLoan * months;//還款總額
        double interest = totalMoney - principal;//還款總利息
        kv.put("totalMoney",format(totalMoney));//還款總額
        kv.put("principal",format(principal));//貸款總額
        kv.put("interest",format(interest));//還款總利息
        kv.put("preLoan",format(preLoan*10000));//每月還款金額
        kv.put("months",months);//還款期限

        return kv;
    }