Numbers to words by method.java

NumberstoWords.java

public class NumberstoWords {
    

    public static void main(String[] args) {

        
        System.out.println(amountInWords(100));


    }
public static String amountInWords(int amount) {
        int t=0;
        int h=0;
        if(amount>=10000) return "Invalid Input (Must be less than 10000)";
        if (amount==0) return "Zero";



        String[] s1 = {"","One ", "Two ", "Three ", "Four ", "Five ", "Six ", "Seven ", "Eight ", "Nine ", "Ten ", "Eleven ", "Twelve ",
                "Thirteen ", "Fourteen ", "Fifteen ", "Sixteen ",
                "Seventeen ", "Eighteen ", "Nineteen "};

        String[] s2 =
                {       "",
                        "Ten ",
                        "Twenty ",
                        "Thirty ",
                        "Forty ",
                        "Fifty ",
                        "Sixty ",
                        "Seventy ",
                        "Eighty ",
                        "Ninety "
                };
        String[] s3 = {"","Thousand ", "Hundred "};

        int[] a=new int[5];
        int c=0;


        while (amount > 0)
        {

            a[c]=(amount%10);
            c++;

            amount /= 10;
        }
        int[] b=new int[5];
        int j=b.length-1;
        for (int i = 0; i <b.length ; i++,j--)
        {
            b[i]=a[j];

        }
        int sum=0;
        if (b[1]!=0) t=1;
        if (b[2]!=0) h=2;

        if (b[3]*10+b[4]<20)
        {   sum=b[3]*10+b[4];
            String toWords1= s1[b[1]]+s3[t]+s1[b[2]]+s3[h]+s1[sum];
            return toWords1;
        }
        else {
            String toWords0 = s1[b[1]] + s3[t] + s1[b[2]] + s3[h] + s2[b[3]] + s1[b[4]];
            return toWords0;
        }
    }
    
   }