将十进制小数转化为二进制小数

import java.math.BigDecimal;
import java.util.Scanner;

public class H4 {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		String input = scanner.nextLine();
		BigDecimal num = BigDecimal.valueOf(Double.parseDouble(input));
		String output="";
		trans(num,output);
	}
	public static void trans(BigDecimal num,String output) {
		num = num.multiply(BigDecimal.valueOf(2));
		String tmp = num.toString().substring(0, 1);//取小数点前一位
		output +=tmp;
		num=num.subtract(BigDecimal.valueOf(Double.parseDouble(tmp)));
		if(num.compareTo(BigDecimal.ZERO)==0||output.length()==10) {//如果num=0或者小数点后有10位就停止递归
			System.out.println("0."+output);
			return;
		}
		trans(num,output);
	}
}