Java Program Number to Word

In this section, we will create a Java program that converts the given number into words. For example, if the given number is 54,297 then the output should be Fifty-Four Thousand Two Hundred Ninety-Seven. Let's create a Java program for the same.

NumberToWordExample1.java

class NumberToWordExample1 
{
//user-defined static method that converts a number into words
static void numberToWords(char num[])
{
//determines the number of digits in the given number
int len = num.length;
//checks the given number has number or not
if (len == 0) 
{
//if the given number is empty prints the following statement 	
System.out.println("The string is empty.");
return;
}
//here, we have specified the length of the number to 4
//it means that the number (that you want to convert) should be four or less than four digits
if (len > 4) 
{
//if the given number is more than four-digit number, it prints the following statement  
System.out.println("\n The given number has more than 4 digits.");
return;
}
//string type array for one-digit numbers  
String[] onedigit = new String[] {"Zero", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine"};
//string type array for two digits numbers  
//the first index is empty because it makes indexing easy 
String[] twodigits = new String[] {"", "Ten", "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen"};
//string type array of tens multiples 
//the first two indexes are empty because it makes indexing easy 
String[] multipleoftens = new String[] {"",	 "", "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety"};
//string type array of power of tens 
String[] poweroftens = new String[] {"Hundred", "Thousand"};
//Used for debugging purpose only 
//the valueOf() method returns the string representation of the character array argument
System.out.print(String.valueOf(num) + ": ");
//checks whether the length of the given string is one or not
if (len == 1) 
{
//if the above condition returns true, it accesses the corresponding index and prints the value of that index
//[num[0]-'0']: getting the number equal the decimal value of the character (assuming the char is the digit)
System.out.println(onedigit[num[0]-'0']);
return;
}
int x = 0;
//executes until num does not become not '\0'
while (x < num.length) 
{
//executes if the length of the string is greater than equal to three
if (len >= 3) 
{
if (num[x] - '0' != 0) 
{
System.out.print(onedigit[num[x] - '0'] + " ");
//here length can be 3 or 4
System.out.print(poweroftens[len - 3]+ " ");
}
//decrements the length of the string by 1
--len;
}
//executes if the given number has two digits
else 
{
//the if-statement handles the numbers from 10 to 19 only	
if (num[x] - '0' == 1) 
{
//adding the digits of the given number	
//the logic behind sum up the digits is that we will use the sum for accessing the index of the array 
//for example: 17, sum of digits = 8
//we will access the 8th index in twodigits[] array i.e. Seventeen
int sum = num[x] - '0' + num[x + 1] - '0';
System.out.println(twodigits[sum]);
return;
}
//the else-if statement handles the number 20 only
//compares the tens and unit place with 2 and 0 respectively
else if (num[x] - '0' == 2 && num[x + 1] - '0' == 0) 
{
//executes if the above else-if condition returns true	
System.out.println("Twenty");
return;
}
//the else block handles the numbers from 21 to 100
else 
{
int i = (num[x] - '0');
if (i > 0)
//prints the ith index element of the array multipleoftens[]
System.out.print(multipleoftens[i]+ " ");
else
//prints space
System.out.print("");
//increments the variable i by 1
++x;
//checks whether the number is not equal to zero, it means the number has only a digit
if (num[x] - '0' != 0)
//prints the ith index element of the array onedigit[]
System.out.println(onedigit[num[x] - '0']);
}
}
//increments the variable i by 1
++x;
}
}
//main() method
public static void main(String args[])
{
//calling the user-defined method and that invokes another predefined method toCharArray()
//the method toCharArray() converts the given number into character array
numberToWords("1111".toCharArray());
numberToWords("673".toCharArray());
numberToWords("85".toCharArray());
numberToWords("5".toCharArray());
numberToWords("0".toCharArray());
numberToWords("20".toCharArray());
numberToWords("1000".toCharArray());
numberToWords("12345".toCharArray());
//passing empty string 
numberToWords("".toCharArray());
}
}

Output:

The number is not limited to four digits. Then what if the user enters more than 5 five digits numbers. The above program does not work for large digit numbers.

Converting Large Numbers into Words

The logic for converting the large digit numbers is quite different. Let's see the approach to convert large digits numbers.

NumberToWordExample2.java

import java.text.DecimalFormat;
public class NumberToWordExample2 
{
//string type array for one digit numbers  	
private static final String[] twodigits = {"", " Ten", " Twenty", " Thirty", " Forty", " Fifty", " Sixty", " Seventy", " Eighty", " Ninety"};
//string type array for two digits numbers 
private static final String[] onedigit = {"", " One", " Two", " Three", " Four", " Five", " Six", " Seven", " Eight", " Nine", " Ten", " Eleven", " Twelve", " Thirteen", " Fourteen", " Fifteen", " Sixteen", " Seventeen", " Eighteen", " Nineteen"};
//defining constructor of the class
private NumberToWordExample2() 
{
}
//user-defined method that converts a number to words (up to 1000)
private static String convertUptoThousand(int number) 
{
String soFar;
if (number % 100 < 20)
{
soFar = onedigit[number % 100];
number = number/ 100;
}
else 
{
soFar = onedigit[number % 10];
number = number/ 10;
soFar = twodigits[number % 10] + soFar;
number = number/ 10;
}
if (number == 0) 
return soFar;
return onedigit[number] + " Hundred " + soFar;
}
//user-defined method that converts a long number (0 to 999999999) to string  
public static String convertNumberToWord(long number) 
{
//checks whether the number is zero or not
if (number == 0) 
{ 
//if the given number is zero it returns zero
return "zero"; 
}
//the toString() method returns a String object that represents the specified long
String num = Long.toString(number);
//for creating a mask padding with "0" 
String pattern = "000000000000";
//creates a DecimalFormat using the specified pattern and also provides the symbols for the default locale
DecimalFormat decimalFormat = new DecimalFormat(pattern);
//format a number of the DecimalFormat instance
num = decimalFormat.format(number);
//format: XXXnnnnnnnnn
//the subString() method returns a new string that is a substring of this string
//the substring begins at the specified beginIndex and extends to the character at index endIndex - 1
//the parseInt() method converts the string into integer
int billions = Integer.parseInt(num.substring(0,3));
//format: nnnXXXnnnnnn
int millions  = Integer.parseInt(num.substring(3,6));
//format: nnnnnnXXXnnn
int hundredThousands = Integer.parseInt(num.substring(6,9));
//format: nnnnnnnnnXXX
int thousands = Integer.parseInt(num.substring(9,12));
String tradBillions;
switch (billions) 
{
case 0:
tradBillions = "";
break;
case 1 :
tradBillions = convertUptoThousand(billions)+ " Billion ";
break;
default :
tradBillions = convertUptoThousand(billions)+ " Billion ";
}
String result =  tradBillions;
String tradMillions;
switch (millions) 
{
case 0:
tradMillions = "";
break;
case 1 :
tradMillions = convertUptoThousand(millions)+ " Million ";
break;
default :
tradMillions = convertUptoThousand(millions)+ " Million ";
}
result =  result + tradMillions;
String tradHundredThousands;
switch (hundredThousands) 
{
case 0:
tradHundredThousands = "";
break;
case 1 :
tradHundredThousands = "One Thousand ";
break;
default :
tradHundredThousands = convertUptoThousand(hundredThousands)+ " Thousand ";
}
result =  result + tradHundredThousands;
String tradThousand;
tradThousand = convertUptoThousand(thousands);
result =  result + tradThousand;
//removing extra space if any
return result.replaceAll("^\\s+", "").replaceAll("\\b\\s{2,}\\b", " ");
}
//main() method
public static void main(String args[]) 
{
//calling the user-defined method that converts the parsed number into words
System.out.println(convertNumberToWord(2));
System.out.println(convertNumberToWord(99));
System.out.println(convertNumberToWord(456));
System.out.println(convertNumberToWord(1101));
System.out.println(convertNumberToWord(19812));
System.out.println(convertNumberToWord(674319));
System.out.println(convertNumberToWord(909087531));
System.out.println(convertNumberToWord(1000000000));
System.out.println(convertNumberToWord(359999999));
System.out.println(convertNumberToWord(1213000000L));
System.out.println(convertNumberToWord(1000000));
System.out.println(convertNumberToWord(1111111111));
System.out.println(convertNumberToWord(3000200));
System.out.println(convertNumberToWord(700000));
System.out.println(convertNumberToWord(9000000));
}
}

Output:

Converting Very Long Numbers into Words

The logic for the conversion of very long numbers into words is different from the previous one. Before moving ahead, it is important to learn the name of large numbers. The following table describes the name of the larger numbers.

Name	Short Scale (US, English Canada, modern British, Australia, and Eastern Europe)	Long Scale (French Canada, older British, Western & Central Europe)
Million	10⁶	10⁶
Milliard	Not used	10⁹
Billion	10⁹	10¹²
Billiard	Not used	10¹⁵
Trillion	10¹²	10¹⁸
Quadrillion	10¹⁵	10²⁴
Quintillion	10¹⁸	10³⁰
Sextillion	10²¹	10³⁶
Septillion	10²⁴	10⁴²
Octillion	10²⁷	10⁴⁸
Nonillion	10³⁰	10⁵⁴
Decillion	10³³	10⁶⁰
Undecillion	10³⁶	10⁶⁶
Duodecillion	10³⁹	10⁷²
Tredecillion	10⁴²	10⁷⁸
Quattuordecillion	10⁴⁵	10⁸⁴
Quindecillion	10⁴⁸	10⁹⁰
Sexdecillion	10⁵¹	10⁹⁶
Septendecillion	10⁵⁴	10¹⁰²
Octodecillion	10⁵⁷	10¹⁰⁸
Novemdecillion	10⁶⁰	10¹¹⁴
Vigintillion	10⁶³	10¹²⁰
Centillion	10³⁰³	10⁶⁰⁰

Let's create a Java program that converts very long numbers into words.

The following Java program also converts the negative and decimal numbers into words.

NumberToWordExample3.java

import java.util.*;
public class NumberToWordExample3 
{
static public class ScaleUnit 
{
private int exponent;
private String[] names;
private ScaleUnit(int exponent, String...names) 
{
this.exponent = exponent;
this.names = names;
}
public int getExponent() 
{
return exponent;
}
public String getName(int index) 
{
return names[index];
}
}
static private ScaleUnit[] SCALE_UNITS = new ScaleUnit[] 
{
new ScaleUnit(63, "vigintillion", "decilliard"),
new ScaleUnit(60, "novemdecillion", "decillion"),
new ScaleUnit(57, "octodecillion", "nonilliard"),
new ScaleUnit(54, "septendecillion", "nonillion"),
new ScaleUnit(51, "sexdecillion", "octilliard"),
new ScaleUnit(48, "quindecillion", "octillion"),
new ScaleUnit(45, "quattuordecillion", "septilliard"),
new ScaleUnit(42, "tredecillion", "septillion"),
new ScaleUnit(39, "duodecillion", "sextilliard"),
new ScaleUnit(36, "undecillion", "sextillion"),
new ScaleUnit(33, "decillion", "quintilliard"),
new ScaleUnit(30, "nonillion", "quintillion"),
new ScaleUnit(27, "octillion", "quadrilliard"),
new ScaleUnit(24, "septillion", "quadrillion"),
new ScaleUnit(21, "sextillion", "trilliard"),
new ScaleUnit(18, "quintillion", "trillion"),
new ScaleUnit(15, "quadrillion", "billiard"),
new ScaleUnit(12, "trillion", "billion"),
new ScaleUnit(9, "billion", "milliard"),
new ScaleUnit(6, "million", "million"),
new ScaleUnit(3, "thousand", "thousand"),
new ScaleUnit(2, "hundred", "hundred"),
//new ScaleUnit(1, "ten", "ten"),
//new ScaleUnit(0, "one", "one"),
new ScaleUnit(-1, "tenth", "tenth"),
new ScaleUnit(-2, "hundredth", "hundredth"),
new ScaleUnit(-3, "thousandth", "thousandth"),
new ScaleUnit(-4, "ten-thousandth", "ten-thousandth"),
new ScaleUnit(-5, "hundred-thousandth", "hundred-thousandth"),
new ScaleUnit(-6, "millionth", "millionth"),
new ScaleUnit(-7, "ten-millionth", "ten-millionth"),
new ScaleUnit(-8, "hundred-millionth", "hundred-millionth"),
new ScaleUnit(-9, "billionth", "milliardth"),
new ScaleUnit(-10, "ten-billionth", "ten-milliardth"),
new ScaleUnit(-11, "hundred-billionth", "hundred-milliardth"),
new ScaleUnit(-12, "trillionth", "billionth"),
new ScaleUnit(-13, "ten-trillionth", "ten-billionth"),
new ScaleUnit(-14, "hundred-trillionth", "hundred-billionth"),
new ScaleUnit(-15, "quadrillionth", "billiardth"),
new ScaleUnit(-16, "ten-quadrillionth", "ten-billiardth"),
new ScaleUnit(-17, "hundred-quadrillionth", "hundred-billiardth"),
new ScaleUnit(-18, "quintillionth", "trillionth"),
new ScaleUnit(-19, "ten-quintillionth", "ten-trillionth"),
new ScaleUnit(-20, "hundred-quintillionth", "hundred-trillionth"),
new ScaleUnit(-21, "sextillionth", "trilliardth"),
new ScaleUnit(-22, "ten-sextillionth", "ten-trilliardth"),
new ScaleUnit(-23, "hundred-sextillionth", "hundred-trilliardth"),
new ScaleUnit(-24, "septillionth","quadrillionth"),
new ScaleUnit(-25, "ten-septillionth","ten-quadrillionth"),
new ScaleUnit(-26, "hundred-septillionth","hundred-quadrillionth"),
};
static public enum Scale 
{
SHORT,
LONG;
public String getName(int exponent) 
{
for (ScaleUnit unit : SCALE_UNITS) 
{
if (unit.getExponent() == exponent) 
{
return unit.getName(this.ordinal());
}
}
return ""; 
}
}
/**
* Change this scale to support American and modern British value (short scale)
* or Traditional British value (long scale)
*/
static public Scale SCALE = Scale.SHORT; 
static abstract public class AbstractProcessor 
{
static protected final String SEPARATOR = " ";
static protected final int NO_VALUE = -1;
protected List<Integer> getDigits(long value) 
{
ArrayList<Integer> digits = new ArrayList<Integer>();
if (value == 0)
{
digits.add(0);
} 
else 
{
while (value > 0) 
{
digits.add(0, (int) value % 10);
value /= 10;
}
}
return digits;
}
public String getName(long value) 
{
return getName(Long.toString(value));
}
public String getName(double value) 
{
return getName(Double.toString(value));
}
abstract public String getName(String value);
}
static public class UnitProcessor extends AbstractProcessor 
{
static private final String[] TOKENS = new String[] 
{
"one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen"
};
@Override
public String getName(String value) 
{
StringBuilder buffer = new StringBuilder();
int offset = NO_VALUE;
int number;
if (value.length() > 3) 
{
number = Integer.valueOf(value.substring(value.length() - 3), 10);
} 
else 
{
number = Integer.valueOf(value, 10);
}
number %= 100;
if (number < 10) 
{
offset = (number % 10) - 1;
//number /= 10;
} 
else if (number < 20) 
{
offset = (number % 20) - 1;
//number /= 100;
}
if (offset != NO_VALUE && offset < TOKENS.length) 
{
buffer.append(TOKENS[offset]);
}
return buffer.toString();
}
}
static public class TensProcessor extends AbstractProcessor 
{
static private final String[] TOKENS = new String[] 
{
"twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety"
};
static private final String UNION_SEPARATOR = "-";
private UnitProcessor unitProcessor = new UnitProcessor();
@Override
public String getName(String value) 
{
StringBuilder buffer = new StringBuilder();
boolean tensFound = false;
int number;
if (value.length() > 3) 
{
number = Integer.valueOf(value.substring(value.length() - 3), 10);
} 
else 
{
number = Integer.valueOf(value, 10);
}
number %= 100;   // keep only two digits
if (number >= 20) 
{
buffer.append(TOKENS[(number / 10) - 2]);
number %= 10;
tensFound = true;
}
else 
{
number %= 20;
}
if (number != 0) 
{
if (tensFound) 
{
buffer.append(UNION_SEPARATOR);
}
buffer.append(unitProcessor.getName(number));
}
return buffer.toString();
}
}
static public class HundredProcessor extends AbstractProcessor 
{
private int EXPONENT = 2;
private UnitProcessor unitProcessor = new UnitProcessor();
private TensProcessor tensProcessor = new TensProcessor();
@Override
public String getName(String value) 
{
StringBuilder buffer = new StringBuilder();
int number;
if (value.isEmpty()) 
{
number = 0;
} 
else if (value.length() > 4) 
{
number = Integer.valueOf(value.substring(value.length() - 4), 10);
}
else 
{
number = Integer.valueOf(value, 10);
}
number %= 1000;  // keep at least three digits
if (number >= 100) 
{
buffer.append(unitProcessor.getName(number / 100));
buffer.append(SEPARATOR);
buffer.append(SCALE.getName(EXPONENT));
}
String tensName = tensProcessor.getName(number % 100);
if (!tensName.isEmpty() && (number >= 100)) 
{
buffer.append(SEPARATOR);
}
buffer.append(tensName);
return buffer.toString();
}
}
static public class CompositeBigProcessor extends AbstractProcessor 
{
private HundredProcessor hundredProcessor = new HundredProcessor();
private AbstractProcessor lowProcessor;
private int exponent;
public CompositeBigProcessor(int exponent) 
{
if (exponent <= 3) 
{
lowProcessor = hundredProcessor;
} 
else 
{
lowProcessor = new CompositeBigProcessor(exponent - 3);
}
this.exponent = exponent;
}
public String getToken() 
{
return SCALE.getName(getPartDivider());
}
protected AbstractProcessor getHighProcessor() 
{
return hundredProcessor;
}
protected AbstractProcessor getLowProcessor() 
{
return lowProcessor;
}
public int getPartDivider() 
{
return exponent;
}
@Override
public String getName(String value) 
{
StringBuilder buffer = new StringBuilder();
String high, low;
if (value.length() < getPartDivider()) 
{
high = "";
low = value;
} 
else 
{
int index = value.length() - getPartDivider();
high = value.substring(0, index);
low = value.substring(index);
}
String highName = getHighProcessor().getName(high);
String lowName = getLowProcessor().getName(low);
if (!highName.isEmpty()) 
{
buffer.append(highName);
buffer.append(SEPARATOR);
buffer.append(getToken());
if (!lowName.isEmpty()) 
{
buffer.append(SEPARATOR);
}
}
if (!lowName.isEmpty()) 
{
buffer.append(lowName);
}
return buffer.toString();
}
}
static public class DefaultProcessor extends AbstractProcessor 
{
static private String MINUS = "minus";
static private String UNION_AND = "and";
static private String ZERO_TOKEN = "zero";
private AbstractProcessor processor = new CompositeBigProcessor(63);
@Override
public String getName(String value) 
{
boolean negative = false;
if (value.startsWith("-")) 
{
negative = true;
value = value.substring(1);
}
int decimals = value.indexOf(".");
String decimalValue = null;
if (0 <= decimals) 
{
decimalValue = value.substring(decimals + 1);
value = value.substring(0, decimals);
}
String name = processor.getName(value);
if (name.isEmpty()) 
{
name = ZERO_TOKEN;
} 
else if (negative) 
{
name = MINUS.concat(SEPARATOR).concat(name); 
}
if (!(null == decimalValue || decimalValue.isEmpty())) 
{
name = name.concat(SEPARATOR).concat(UNION_AND).concat(SEPARATOR)
.concat(processor.getName(decimalValue)).concat(SEPARATOR).concat(SCALE.getName(-decimalValue.length()));
}
return name;
}
}
static public AbstractProcessor processor;
public static void main(String...args) 
{
processor = new DefaultProcessor();
long[] values = new long[] 
{            0,4,10,12,100,108,299,1000,1003,2040,45213,100000,100005,100010,202020,202022,999999,1000000,1000001,10000000,10000007,99999999,
Long.MAX_VALUE,
Long.MIN_VALUE
};
String[] strValues = new String[] 
{
"0001.2","3.141592"
};
for (long val : values) 
{
System.out.println(val + " = " + processor.getName(val) );
}
for (String strVal : strValues) 
{
System.out.println(strVal + " = " + processor.getName(strVal) );
}
//generates a very large number
StringBuilder bigNumber = new StringBuilder();
for (int d=0; d<66; d++) 
{
bigNumber.append( (char) ((Math.random() * 10) + '0'));
}
bigNumber.append(".");
for (int d=0; d<26; d++) 
{
bigNumber.append( (char) ((Math.random() * 10) + '0'));
}
System.out.println(bigNumber.toString() + " = " + processor.getName(bigNumber.toString()));
}
}

Output:

0 = zero
4 = four
10 = ten
12 = twelve
100 = one hundred
108 = one hundred eight
299 = two hundred ninety-nine
1000 = one thousand
1003 = one thousand three
2040 = two thousand forty
45213 = forty-five thousand two hundred thirteen
100000 = one hundred thousand
100005 = one hundred thousand five
100010 = one hundred thousand ten
202020 = two hundred two thousand twenty
202022 = two hundred two thousand twenty-two
999999 = nine hundred ninety-nine thousand nine hundred ninety-nine
1000000 = one million
1000001 = one million one
10000000 = ten million
10000007 = ten million seven
99999999 = ninety-nine million nine hundred ninety-nine thousand nine hundred ninety-nine
9223372036854775807 = nine quintillion two hundred twenty-three quadrillion three hundred seventy-two trillion thirty-six billion eight hundred fifty-four million seven hundred seventy-five thousand eight hundred seven
-9223372036854775808 = minus nine quintillion two hundred twenty-three quadrillion three hundred seventy-two trillion thirty-six billion eight hundred fifty-four million seven hundred seventy-five thousand eight hundred eight
0001.2 = one and two tenth
3.141592 = three and one hundred forty-one thousand five hundred ninety-two millionth

Even, we can convert 100 digits long number with the help of the above program.

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