java读取txt字符串挨个写入int数组

int []num=new int[1001];
  FileReader fr = new FileReader("1.txt");
  BufferedReader br = new BufferedReader(fr);

String str;
  StringBuilder sb = new StringBuilder();
  while((str=br.readLine())!=null)
  {
   sb.append(str);
  }
  String st=sb.toString();
   int sum=0,mynum;
   for(int i=0;i<st.length();i++)
   {
    num[i]=Integer.parseInt(st.substring(i,i+1));
   }

乍看 很麻烦！