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  • Java基础之IO流,按字符读取文件(一)

    import java.io.*;

    class FileReaderDemo
    {
        public static void main(String[] args)
        {
            /*
                创建一个文件读取流,和指定名称的文件相关联。
                要保证该文件是已经存在的,如果不存在,会发生异常:FileNotFoundException
                创建对象引用:
            
    */
            FileReader fr = null;
            try
            {
                //实例化对象
                fr = new FileReader("demo.txt");
                
                /*
                    读取单个字符:
                    int c1 = fr.read();
                    sop((char)c1);
                    
                    int c2 = fr.read();
                    sop((char)c2);
                    
                    int c3 = fr.read();
                    sop((char)c3);
                    
                    FileReader的read方法,在读取完一个字符后会自动向下读取,直到读到-1为止,这是一个循环动作
                
                    while(true)
                    {
                        int ch = fr.read();
                        if(-1!=ch)
                            break;
                            
                        sop((char)ch);
                    }
                
    */
                
                //优化过的读取方式:
                int ch = 0;
                while((ch=fr.read()) != -1)
                {
                    System.out.print((char)ch);
                }            
            }
            catch(IOException e)
            {
                sop("Error:"+e.getMessage());
            }
            finally
            {
                try            
                {
                    if(null!=fr) fr.close();
                }
                catch(IOException e)
                {
                    sop("Error:"+e.getMessage());
                }
            }
        }
        
        public static void sop(Object obj)
        {
            System.out.println(obj);
        }
    }
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  • 原文地址:https://www.cnblogs.com/cxmsky/p/2880877.html
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