题解 | #人民币转换#

public class Main {
    private static String[] word = new String[]{"零", "壹", "贰", "叁", "肆", "伍", "陆", "柒", "捌", "玖"};
    //小数点之前
    private static String[] frontUnits = new String[]{"元", "拾", "佰", "仟", "万", "亿", "整"};
    //小数点之后
    private static String[] behindUnits = new String[]{"角", "分"};

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNext()) {
            System.out.println(getMoney(scanner.nextLine()));
        }
        scanner.close();
    }

    private static String getMoney(String money) {
        int indexOfDot = money.indexOf(".");
        //如果没有点，则补充点。
        if (indexOfDot < 0) {
            money = money + ".00";
        } else if (indexOfDot == money.length() - 2) {
            money = money + "0";
        }
        indexOfDot = money.indexOf(".");
        StringBuilder frontBuilder = new StringBuilder(money.substring(0, indexOfDot));
        StringBuilder behindBuilder = new StringBuilder(money.substring(indexOfDot + 1));
        return getFrontMoney(frontBuilder) + (getBehindMoney(behindBuilder));
    }

    /**
     * 获取点之前的money
     * 1仟1佰1拾1亿   1仟1佰1拾1万 1仟1佰1拾1元
     *
     * @param frontBuilder
     * @return
     */
    private static String getFrontMoney(StringBuilder frontBuilder) {
        StringBuilder frontSb = new StringBuilder();
        frontSb.append("人民币");
        for (int i = 0; i < frontBuilder.length(); i++) {
            char currentChar = frontBuilder.charAt(i);
            int currentNum = Integer.parseInt(currentChar + "");
            int frontIndex = frontBuilder.length() - i - 1;

            switch (currentNum) {
                case 0:
                    if (i > 0) {
                        char lastChar = frontBuilder.charAt(i - 1);
                        int lastNum = Integer.parseInt(lastChar + "");
                        System.out.println("lastNum:" + lastNum);
                        if (lastNum != 0 && frontIndex % 4 != 0 && frontIndex % 4 != 1) {
                            frontSb.append(word[currentNum]);
                        }
                    }

                    break;
                case 1:
                    if (frontIndex != 1) {
                        frontSb.append(word[currentNum]);
                    }
                    break;
                default:
                    frontSb.append(word[currentNum]);
                    break;
            }

            //倒序的获取单位（"元", "拾", "佰", "仟", "万", "亿", "整"）
            if (currentNum != 0) {
                frontSb.append(getFrontUnit(frontIndex));
            } else {
                if (frontIndex == 0 && i != 0) {
                    frontSb.append(getFrontUnit(frontIndex));
                }
            }


        }
        return frontSb.toString();
    }

    /**
     * 获取点之后的money
     * . 1角1分
     *
     * @param behindBuilder
     * @return
     */
    private static String getBehindMoney(StringBuilder behindBuilder) {
        StringBuilder behindSb = new StringBuilder();
        for (int i = 0; i < behindBuilder.length(); i++) {
            char currentChar = behindBuilder.charAt(i);
            int currentNum = Integer.parseInt(currentChar + "");

            if (currentNum == 0) {
                if (i == 0) {
                    int nextNum = Integer.parseInt(behindBuilder.charAt(i + 1) + "");
                    if (nextNum == 0) {
                        behindSb.append(frontUnits[6]);
                    }
                }

            } else {
                behindSb.append(word[currentNum]);
                behindSb.append(getBehindUnit(i));
            }
        }

        return behindSb.toString();
    }


    /**
     * 获取点之前的单位
     * 1仟1佰1拾1亿   1仟1佰1拾1万 1仟1佰1拾1元 . 1角1分
     *
     * @param index 点之前各数的index：靠近小数点的为圆点
     * @return 小数点之前的单位
     */
    private static String getFrontUnit(int index) {
        int x = index % 4;
        int i = index / 4;
        String unit = "";
        switch (x) {
            case 3://仟
                unit = frontUnits[3];
                break;
            case 0://元，万，亿
                switch (i) {
                    case 0://元
                        //2、中文大写金额数字到“元”为止的，在“元”之后，应写“整字，如532.00应写成“人民币伍佰叁拾贰元整”。在”角“和”分“后面不写”整字。
                        unit = frontUnits[0];
                        break;
                    case 1://"万"
                        unit = frontUnits[4];
                        break;
                    case 2://"亿"
                        unit = frontUnits[5];
                        break;
                    default:
                        break;
                }
                break;
            case 2://佰
                unit = frontUnits[2];

                break;
            case 1://拾
                unit = frontUnits[1];
                break;
            default:
                break;
        }
        return unit;
    }

    /**
     * 获取点之后的单位
     * . 1角1分
     *
     * @param index 点之后各数的index  靠近小数点的为圆点
     * @return 小数点之后的单位
     */
    private static String getBehindUnit(int index) {
        return behindUnits[index];
    }
}