10、金额转换，阿拉伯数字转换成中国传统形式。 例如：101000001010 转换为 壹仟零壹拾億零壹仟零壹拾圆整。此题的解题主要要抓住几个关键点，1.判断录入的数字是否合法首先录入的数据要验证它是否是合法的数字，这个验证的方法我第一想到的是使用正则表达式来处理，但是我写了很多正则都没能满足要求，就暂时用if else代替了。
2.根据要求的精度舍去多的小数位数的数字，并且去掉末尾的0和多余的小数点，需要用到while语句循环处理直到满足要求为止
3.数字转换 单位转换
·在数字的转换的过程中药分整数和负数两种情况，负数的起始index返回的是符号-不是数字，所以巧妙的设计一个判断数字正负的if语句把后面要遍历循环的起始参数变量初始化为0或者1。
·添加单位和数字也是有讲究的，使用StringTokenizer类按照符号"."将字符串分成小数部分和整数部分分别来处理。小数部分的单位转换和数字转换比较容易，就是依次给非0的数字加上中文的数字和单位即可。整数部分的添加就要注意了是从低位向高位依次添加单位，然后再插入数字，在这个逆向的遍历操作中，用if语句判断起始字符串是否为零的情况来控制重复加零的操作。 ·最后提醒自己完善一些细节： -先判断出数值就为零的情况直接返回 -整数部分的处理，StringBuilder初始化字符串是币种单位“圆” -最后给整数部分和小数部分都添加完单位和数字后，判断是否为负数给字符串加前缀“负”，判断有没有小数部分给字符串加后缀 “整”。
4.以上转换得到的字符串中存在零十、零百、零千、零万、零億和以圆、负圆开头的字符的情况，分别过滤掉前面的零？和 以圆、负圆开头的字符中的“圆”字符
主要代码如下:
package lqq.heima.matriculation.subject10;
import java.util.HashMap;
public class Units {
public static final String EMPTY = ""; public static final String ZERO = "零"; public static final String ONE = "壹"; public static final String TWO = "贰"; public static final String THREE = "叁"; public static final String FOUR = "肆"; public static final String FIVE = "伍"; public static final String SIX = "陆"; public static final String SEVEN = "柒"; public static final String EIGHT = "捌"; public static final String NINE = "玖"; public static final String TEN = "拾"; public static final String HUNDRED = "佰"; public static final String THOUSAND = "仟"; public static final String TEN_THOUSAND = "万"; public static final String HUNDRED_MILLION = "億"; public static final String YUAN = "圆"; public static final String JIAO = "角"; public static final String FEN = "分"; public static final String DOT = "."; public static final String ZHENG ="整"; public static final String MINUS = "-"; public static final String MINUS_TO_CHINESE = "负"; public static final String PATTERN ="0123456789."; public static final int MAXIMUM_FRACTION_DIGITS = 2;
private static Units units = null; private HashMap<String, String> chineseNumberMap = new HashMap<String, String>(); private HashMap<String, String> chineseMoneyPattern = new HashMap<String, String>();
private Units() {
chineseNumberMap.put("0", ""); chineseNumberMap.put("1", ONE); chineseNumberMap.put("2", TWO); chineseNumberMap.put("3", THREE); chineseNumberMap.put("4", FOUR); chineseNumberMap.put("5", FIVE); chineseNumberMap.put("6", SIX); chineseNumberMap.put("7", SEVEN); chineseNumberMap.put("8", EIGHT); chineseNumberMap.put("9", NINE); chineseNumberMap.put(DOT, DOT);
chineseMoneyPattern.put("1", TEN); chineseMoneyPattern.put("2", HUNDRED); chineseMoneyPattern.put("3", THOUSAND); chineseMoneyPattern.put("4", TEN_THOUSAND); chineseMoneyPattern.put("5", HUNDRED_MILLION); }
public static Units getInstance() { if (units == null) units = new Units(); return units; }
public HashMap<String, String> getChineseNumberMap() { return chineseNumberMap; }
public HashMap<String, String> getChineseMoneyPattern() { return chineseMoneyPattern; }
}
package lqq.heima.matriculation.subject10;
import java.util.StringTokenizer;
@SuppressWarnings("static-access")public class SimpleMoneyFormat {
private Units units; private String prefix; private String suffix; private String symbol = "+";
public SimpleMoneyFormat() { this.units = Units.getInstance(); }
public String format(String num) {
num = num.trim(); String result = ""; if (isPattern(num)) { if (num.startsWith(Units.MINUS)) { this.symbol = Units.MINUS; num = num.substring(1); } spit(round(num)); result = addUnitsToChineseMoneyString(); } else { System.out.println("非法数字。"); }
return filter(result); }
private boolean isPattern(String num) {
// return num.matches("^//d+$"); boolean flag = true; int i; // 正负数 int count = 0; // 计算小数点个数
// 不为空 if (num != null && !num.equals("")) { // 正负数 if (num.startsWith("-")) i = 1; else i = 0;
if (String.valueOf(num.charAt(i)).equals("0")) { int temp = i;
if (!String.valueOf(num.charAt(++temp)).equals(Units.DOT)) { flag = false; return flag; } }
for (; i < num.length() - 1; i++) { if (units.PATTERN.indexOf(num.charAt(i)) == -1) { flag = false; return flag;
}
if ((num.charAt(i) + "").equals(".")) count++; }
// 小数点后没数据 if (num.endsWith(".")) flag = false;
// 不止一個小數點 if (count > 1) flag = false; }
return flag;
}
private String filter(String result) { String temp = result.replace(units.ZERO + units.TEN, "").replace( units.ZERO + units.HUNDRED, "").replace( units.ZERO + units.THOUSAND, "").replace( units.ZERO + units.TEN_THOUSAND, "").replace( units.ZERO + units.HUNDRED_MILLION, ""); if (temp.startsWith(Units.YUAN) || temp.startsWith("负" + Units.YUAN)) { temp = temp.replace(Units.YUAN, ""); } return temp; }
private String round(String num) { String result = ""; if (num.indexOf(units.DOT) != -1) { int length = num.length() - (num.indexOf(Units.DOT) + 1);
if (length > Units.MAXIMUM_FRACTION_DIGITS) {
result = num .substring( 0, (num.length() - (length - Units.MAXIMUM_FRACTION_DIGITS)));
} else { result = num; } while (result.endsWith("0") || result.endsWith(Units.DOT)) { result = result.substring(0, result.length() - 1); }
} else { result = num; } return result; }
/** * @function 整数部分、小数部分初始化 */ private void spit(String num) { StringTokenizer st = new StringTokenizer(num, Units.DOT);
if (st.countTokens() == 1) prefix = st.nextToken(); else if (st.countTokens() == 2) { prefix = st.nextToken(); suffix = st.nextToken(); } }
/** * * @param moneyStr * @return */ private String addUnitsToChineseMoneyString() { String result = Units.YUAN;
int count = 0;
// 整数部分转换 for (int i = prefix.length() - 1; i >= 0; i--) { count++;
int j = Integer.parseInt(prefix.charAt(i) + ""); // 当前数字
if (j == 0) {
if (!result.startsWith(units.ZERO) && count > 1) {
result = units.ZERO + result; }
// 万位、亿位上为零，需要添加单位 if ((count - 1) > 0 && (count - 1) % 4 == 0) { if ((count - 1) % 8 == 0) result = units.HUNDRED_MILLION + result; else result = units.TEN_THOUSAND + result; } } else { // 添加计量单位 if (count % 2 == 0 && count % 4 != 0) result = units.TEN + result; else if ((count + 1) % 4 == 0) result = units.HUNDRED + result; else if (count % 4 == 0) result = units.THOUSAND + result; else if ((count - 1) > 0 && (count - 1) % 4 == 0 && (count - 1) % 8 != 0) result = units.TEN_THOUSAND + result; else if ((count - 1) > 0 && (count - 1) % 8 == 0) result = units.HUNDRED_MILLION + result; }
// 数字转大写 result = units.getChineseNumberMap().get(String.valueOf(j)) + result; }
// 判断是否存在小数部分 if (null != suffix) { // 小数部分转换
for (int i = 0; i < suffix.length(); i++) { int k = Integer.parseInt(suffix.charAt(i) + "");
if (k != 0) { result += units.getChineseNumberMap() .get(String.valueOf(k));
if (i == 0) result += units.JIAO; else if (i == 1) result += units.FEN;
} } } else {
result = result + Units.ZHENG; }
// 正负数 if (this.symbol.equals(Units.MINUS)) result = "负" + result;
return result; }}
package lqq.heima.matriculation.subject10;
public class MainClass {
/** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub SimpleMoneyFormat1 smf = new SimpleMoneyFormat1(); String num = "101000001010"; System.out.println(num); System.out.println(smf.format(num));
}
}
