Algorithm to print combinations of elements in given order (Written in Java)

This is an algorithm to print combinations of elements in an array following the lexicographic order. For example if the given array is

{ 'a', 'b', 'c', 'd'}

then the answer should be

 ab, ac, ad, bc, bd, abc, abd, acd, bcd, abcd.


 Given below is the implementation:

	package combinations;
	import java.util.*;
	import java.math.*;
	public class combPowerSet {
	//printing the charachters as per the number sent.
	void printNumber(int number, char [] items)
	{
	String digitString = Integer.toString(number);
	char [] digitStringArray = digitString.toCharArray();
	int length = digitStringArray.length;
	for ( int i=0; i<length; i++)
	{
	System.out.print(items[Character.getNumericValue(digitStringArray[i])-1]);
	}
	System.out.println();
	}
	//checking if the number follows the required pattern.
	boolean checkCondition(int number, int itemSize)
	{
	boolean validNumber = true;
	String digitString = Integer.toString(number);
	char [] digitStringArray = digitString.toCharArray();
	int length = digitStringArray.length;
	for ( int i=0; i<length; i++)
	{
	for( int j = i+1; j < length; j++)
	{
	int x = Character.getNumericValue(digitStringArray[i]);
	int y = Character.getNumericValue(digitStringArray[j]);
	if (x > itemSize-1 || y > itemSize || x > y || x==y)
	{
	validNumber = false;
	break;
	}
	}
	if (validNumber == false) break;
	}
	return validNumber;
	}
	void printCombinations(char [] items)
	{
	double maxDigit = 0;
	int itemSize = items.length;
	for(int i=1; i<=itemSize; i++)
	{
	maxDigit = maxDigit + i*Math.pow(10,itemSize-i);
	}
	for(int x=12; x<=maxDigit; x++)
	{
	if(checkCondition(x, itemSize))
	{
	printNumber(x, items);
	}
	}
	}
	public static void main(String [] args)
	{
	char [] arr = { 'a','b', 'c','d', 'e'};
	combPowerSet obj = new combPowerSet();
	obj.printCombinations(arr);
	}
	}

view raw combPowerSet.java hosted with ❤ by GitHub