number to words java

1class NumberToWordExample1   
2{  
3//user-defined static method that converts a number into words  
4static void numberToWords(char num[])  
5{  
6//determines the number of digits in the given number  
7int len = num.length;  
8//checks the given number has number or not  
9if (len == 0)   
10{  
11//if the given number is empty prints the following statement     
12System.out.println("The string is empty.");  
13return;  
14}  
15//here, we have specified the length of the number to 4  
16//it means that the number (that you want to convert) should be four or less than four digits  
17if (len > 4)   
18{  
19//if the given number is more than four-digit number, it prints the following statement    
20System.out.println("\n The given number has more than 4 digits.");  
21return;  
22}  
23//string type array for one-digit numbers    
24String[] onedigit = new String[] {"Zero", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine"};  
25//string type array for two digits numbers    
26//the first index is empty because it makes indexing easy   
27String[] twodigits = new String[] {"", "Ten", "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen"};  
28//string type array of tens multiples   
29//the first two indexes are empty because it makes indexing easy   
30String[] multipleoftens = new String[] {"",  "", "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety"};  
31//string type array of power of tens   
32String[] poweroftens = new String[] {"Hundred", "Thousand"};  
33//Used for debugging purpose only   
34//the valueOf() method returns the string representation of the character array argument  
35System.out.print(String.valueOf(num) + ": ");  
36//checks whether the length of the given string is one or not  
37if (len == 1)   
38{  
39//if the above condition returns true, it accesses the corresponding index and prints the value of that index  
40//[num[0]-'0']: getting the number equal the decimal value of the character (assuming the char is the digit)  
41System.out.println(onedigit[num[0]-'0']);  
42return;  
43}  
44int x = 0;  
45//executes until num does not become not '\0'  
46while (x < num.length)   
47{  
48//executes if the length of the string is greater than equal to three  
49if (len >= 3)   
50{  
51if (num[x] - '0' != 0)   
52{  
53System.out.print(onedigit[num[x] - '0'] + " ");  
54//here length can be 3 or 4  
55System.out.print(poweroftens[len - 3]+ " ");  
56}  
57//decrements the length of the string by 1  
58--len;  
59}  
60//executes if the given number has two digits  
61else   
62{  
63//the if-statement handles the numbers from 10 to 19 only     
64if (num[x] - '0' == 1)   
65{  
66//adding the digits of the given number   
67//the logic behind sum up the digits is that we will use the sum for accessing the index of the array   
68//for example: 17, sum of digits = 8  
69//we will access the 8th index in twodigits[] array i.e. Seventeen  
70int sum = num[x] - '0' + num[x + 1] - '0';  
71System.out.println(twodigits[sum]);  
72return;  
73}  
74//the else-if statement handles the number 20 only  
75//compares the tens and unit place with 2 and 0 respectively  
76else if (num[x] - '0' == 2 && num[x + 1] - '0' == 0)   
77{  
78//executes if the above else-if condition returns true    
79System.out.println("Twenty");  
80return;  
81}  
82//the else block handles the numbers from 21 to 100  
83else   
84{  
85int i = (num[x] - '0');  
86if (i > 0)  
87//prints the ith index element of the array multipleoftens[]  
88System.out.print(multipleoftens[i]+ " ");  
89else  
90//prints space  
91System.out.print("");  
92//increments the variable i by 1  
93++x;  
94//checks whether the number is not equal to zero, it means the number has only a digit  
95if (num[x] - '0' != 0)  
96//prints the ith index element of the array onedigit[]  
97System.out.println(onedigit[num[x] - '0']);  
98}  
99}  
100//increments the variable i by 1  
101++x;  
102}  
103}  
104//main() method  
105public static void main(String args[])  
106{  
107//calling the user-defined method and that invokes another predefined method toCharArray()  
108//the method toCharArray() converts the given number into character array  
109numberToWords("1111".toCharArray());  
110numberToWords("673".toCharArray());  
111numberToWords("85".toCharArray());  
112numberToWords("5".toCharArray());  
113numberToWords("0".toCharArray());  
114numberToWords("20".toCharArray());  
115numberToWords("1000".toCharArray());  
116numberToWords("12345".toCharArray());  
117//passing empty string   
118numberToWords("".toCharArray());  
119}  
120}