java 二进制和十进制互转

package test1;
public class s01进制 {
    public static final StringBuilder stb = new StringBuilder();
    public static void main(String[] args) {
        dg(18);
        System.out.println(stb.reverse());//10->2
        System.out.println(dg1(10010));//2->10
    }
    public static int dg(int num){//10->2
        if(num<1){
            return 0;
        }
        stb.append(num<=1?1:num%2);
        return dg(num/2);
    }
    public static int dg1(int num){//2->10
        String[] strarr = String.valueOf(num).split("");
        int sum = 0;
        int in = strarr.length-1;
        for (int i=0;i