JAVA拷贝为什么编译会报错啊？

import java.io.*;


public class 拷贝 
{
    public static void main(String[] args)
    {
        String[] str = {"123456"};
        File fid = new File("D\\a.txt");   //创建地址，
        File did = new File("D\\b.txt");
        FileWriter fod = null;  //创建文件写入对象
        FileReader dod = null; //创建文件读取对象
        if ( fid.exists() )
        {
            System.out.println("文件已经存在");
        }
        else
        {
            try
            {
                fid.createNewFile();
                System.out.println("文件创建成功");
            } catch (Exception e)
             {
                 
             }
        }
        try 
        {
            fod = new FileWriter("D\\\\a.txt");
            for (int i=0; i<str.length; i++)
            {
                fod.write(str[i]);
            
            }
        } catch (Exception e)
         {
            
         }
          finally 
           {
              try
              {
                  fod.close();
    
              } catch (IOException e2)
               {
                 
               } 
           }
        
        
        try 
        {
            dod = new FileReader(fid);
            String ctr = null;
            while ( (ctr = dod.read() ) != null )
            {
                System.out.println(ctr);
            }
        } catch (Exception e) 
         {
            // TODO: handle exception
         } finally 
          {
              try
              {
                 dod.close();
              } catch (Exception e2)
              {
                // TODO: handle exception
              }

        
          }
    }
}

这么多try catch ，还不如直接抛一个大个的异常

异常没处理

dod.read()这个的返回值是int，不能这样读取字符串
https://blog.csdn.net/sutaotao_s77/article/details/79251364

修改为ctr = dod.readLine()