java中将一个int型数转化为32位二进制数

public static String toFullBinaryString(int num)//将整数num转化为32位的二进制数
{
  char[] chs = new char[Integer.SIZE];
  for (int i = 0; i < Integer.SIZE; i++)
  {
   chs[Integer.SIZE - 1 - i] = (char) (((num >> i) & 1) + '0');
   System.out.println(chs[Integer.SIZE - 1 - i]);
  }
  return new String(chs);
}