Sistemas numericos en java

//conversion de sistemas Numericos
import javax.swing.*;
import java.io.*;
import java.math.*;
class SistemasNumericos {
String temp;
String finalexa;
String finalocta;
Stringbase16[]={"0000","0001","0010","0011","0100","0101","0110","0111","1000","1001","1010","1011","1100","1101","1110","1111"};
String bas16[]={"0","1","2","3","4","5","6","7","8","9","A","B","C","D","E","F"};String base8[]={"000","001","010","011","100","101","110","111"};
String bas8[]={"0","1","2","3","4","5","6","7"};
char ba8[]={'0','1','2','3','4','5','6','7' };
charba16[]={'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
final static double nu=2;
public SistemasNumericos()
{
temp="";
finalexa="";
finalocta="";
}public void binex(String x)//binario a exadecimal
{
int n=x.length();
while ((n%4)!=0)
{
x="0"+x;
n=x.length();
}for(int i=n-1; i>=0; i=i-4)
{
temp=x.substring(i-3,i+1);
for(int j=0; j<16; j++)
{
if (temp.compareTo(base16[j])==0){
finalexa=bas16[j]+finalexa;
}
} //for
} // for
JOptionPane.showMessageDialog(null,"El resultado es "+ finalexa);
} // binexpublic void binoc (String x)//binario a octal
{
int n=x.length();
while ((n%3)!=0)
{
x="0"+x;
n=x.length();
} //whilefor(int i=n; i>0; i=i-3)
{
temp=x.substring(i-3,i);
System.out.println(temp);
for(int j=0; j<8; j++)
{
if(temp.compareTo(base8[j])==0)
{
finalocta=bas8[j]+finalocta;
}
} //for
} // for
JOptionPane.showMessageDialog(null,"El resultado es "+ finalocta);...