Decimal to Binary and octal

Can someone fix this???

import java.util.*;
public class Convert

{
public static void main(String[] args)

{ 
	int num=0;
	String result = "";
	char repeat; //to hold yes or no
	String OctStr; // to hold Decimal number 
	char c; //to hold each number of input octal
	int i, j, n; 
	
	do
	{		
			//for numbers 1 to 7, make a binary equivalent 
			//of that number to look up later 
			String biArray[]={"0", "1", "10", "11", "100", "101", "110", "111", "1000", "1001", "1010", "1011", "1100", "1101","1111", "10000", "10001", "10010", "10011", "10100", "10101", "10110", "10111", "11000", "11001"};
			
			Scanner input = new Scanner(System.in);
			//System.out.println("Octal to Binary Conversion");		
			System.out.println("Enter the Decimal Number: ");
			OctStr = input.nextLine();
							
			//make a loop to read as many number as the input octal has
			for (i=0; i<OctStr.length(); i++)
			{
				//read string by character then convert to an integer
				c = OctStr.charAt(0);
				
				for (j=0+1; j<c; j++)
				{
					//convert character to integer (ex: "1" to 1)don't know how???
					n = Character.getNumericValue(c);
					if(n <=25)	
					{
					biArray[0] = "0";
					biArray[1] = "1";
					biArray[2] = "10";
					biArray[3] = "11";
					biArray[4] = "100";
					biArray[5] = "101";
					biArray[6] = "110";
					biArray[7] = "111";
                                            biArray[8] = "1000";
                                            biArray[9] = "1001";
                                            biArray[10] = "1010";
                                            biArray[11] = "1011";
                                            biArray[12] = "1100";
                                            biArray[13] = "1101";
                                            biArray[14] = "1110";
                                            biArray[15] = "1111";
                                            biArray[16] = "10000";
                                            biArray[17] = "10001";
					biArray[18] = "10010";
                                            biArray[19] = "10011";
                                            biArray[20] = "10100";
                                            biArray[21] = "10101";
                                            biArray[22] = "10110";
                                            biArray[23] = "10111";
                                            biArray[24] = "11000";
                                            biArray[25] = "11001";
                                            
					System.out.println(OctStr+ " convert to binary is "+ biArray[n]);
					//System.out.println();
					}//end if
					else if(n>25)
						System.out.println( "Not a valid Decimal number!");

				}

			}
							
	  	   // prompt for input more OctNum
			System.out.print("Do you want to enter another Octal number? ");
			
	  	   System.out.println("Y for yes or N for No: ");
			System.out.println();
			
			String str= input.next(); //Read next char
  			repeat= str.charAt(0); //Get the first char
	
	}while(repeat=='Y' || repeat=='y');

}//end main class

}

//read string by character then convert to an integer
c = OctStr.charAt(0);
i think so that’s not exact effective code
try writing code with buffered reader and parseINTEGER

** DECIMAL TO BINARY
#include<stdio.h>
#include<conio.h>

dectobinary(int n)
{
int a;
if(n)
{
a=n%2;
dectobinary(n >> 1);
printf("%d",a);
}
}
void main()
{
int n;
clrscr();
printf(“Enter the number to convert”);
scanf("%d",&n);
a=dectobinary(n);
printf("%d",a);
getch();
}

Is there some reason why you cannot use Integer.parseInt( String s, int radix ) and Integer.toString( int n, int radix ) ?

//