public static void main(String[] args) {
        System.err.println(Integer.toBinaryString(20));
    }

------解决方案--------------------

Java code

public class MyTestMain {
 public StringBuffer getBint(int dec,StringBuffer result)
     {
         result.insert(0, dec%2);
         dec=dec/2;
        if(dec>1)
            result=getBint(dec,result);
        else
            result.insert(0, dec%2);
            return result;
     }
public static void main(String[] args) {
      
     MyTestMain mtm=new MyTestMain();
    System.out.print(mtm.getBint(20, new StringBuffer()));
}
｝