Print Keypad Combinations Code

public class solution {

	public static void printKeypad(int input){
		// Write your code here
		printKeypad(input,"");
	}
    public static void printKeypad(int input,String output){
        if(input==0){
            System.out.println(output);
            return;
        }
        int rem=input%10;
        char helperArray[]=helper(rem);
        printKeypad(input/10,helperArray[0]+output);
         printKeypad(input/10,helperArray[1]+output);
         printKeypad(input/10,helperArray[2]+output);
        
        if(helperArray.length==4){
             printKeypad(input/10,helperArray[3]+output);
        }
    }
    public static char[] helper(int n){
        
        if(n==2){
            char [] str={'a','b','c'};
            return str;
        }else if(n==3){
            char [] str={'d','e','f'};
            return str;
        }else if(n==4){
            char [] str={'g','h','i'};
            return str;
        }else if(n==5){
            char [] str={'j','k','l'};
            return str;
        }else if(n==6){
            char [] str={'m','n','o'};
            return str;
        }else if(n==7){
            char [] str={'p','q','r','s'};
            return str;
        }else if(n==8){
            char [] str={'t','u','v'};
            return str;
        }else if(n==9){
            char[] str={'w','x','y','z'};
            return str;
        }else{
            char [] str={' '};
            return str;
        }
    }
}