public static void main(String[] args ){ int i = 8; String s2 = Integer.toString(i,2); System.out.println("2进制为:"+s2); // -- 1000 int sum = 0; for (int j = 0; j < s2.length(); j++) { int x = Integer.parseInt(String.valueOf(s2.charAt(j))); sum += x * Math.pow(2,(s2.length()-j-1)); } System.out.println("10进制为:"+sum); }