Question

我有一个程序从文件中读取内容并将其打印在屏幕上。但程序打印每隔一行，即每隔一行跳过一次。包InputOutput;

import java.io.*;

public class CharacterFileReaderAndFileWriter{

    private BufferedReader br = null;

    private PrintWriter pw = new PrintWriter(System.out, true);


    /* Read from file and print to console */
    public void readFromFile() throws IOException{

        try{
            br = new BufferedReader(new FileReader("E:\\Programming\\Class files\\practice\\src\\InputOutput\\test.txt"));
        }
        catch(FileNotFoundException ex){
            ex.printStackTrace();
        }

        String s = null;
        do{
            s = br.readLine();
            pw.println(s);
        }
        while((s = br.readLine())!=null);

        br.close();
    }

    /* Main method */
    public static void main(String[] args) throws IOException{

        CharacterFileReaderAndFileWriter cfr = new CharacterFileReaderAndFileWriter();

        cfr.readFromFile();
    }

}

Answer 1

你为什么要做s=br.readline()两次......你可以这样做。

String s = null;
 while((s = br.readLine())!=null)
{
   pw.println(s);
}

每次调用它时，

readline()都会读取一行，然后转到下一行。所以当你两次打电话时，显然你正在跳过一条线。使用此代码，它将工作。

Answer 2

你循环错误：

String s = null;
do{
    s = br.readLine();
    pw.println(s);
}
while((s = br.readLine())!=null);

应该是：

String s = null;
while((s = br.readLine())!=null) {
    pw.println(s);
};

Answer 3

撤消您的do/while循环以避免两次调用readline并丢弃所有其他结果：

String s = null;
while((s = br.readLine())!=null) {
    pw.println(s);
}

Answer 4

删除执行循环的第一行。你两次调用readLine（）。

即：

String s = null;
while((s = br.readLine())!=null) {
    pw.println(s);
}

Answer 5

如果您想使用do-while，则需要修改do-while循环，然后按如下方式对其进行编码。

String s = null;
do{        
    pw.println(s);
}
while((s = br.readLine())!=null);

br.close();

Answer 6

更改：

  for(String s; (s = br.readLine()) != null;) {
        pw.println(s);
  }

Answer 7

你正在使用br.readLine（）两次。

String s = null;
    do{
        s = br.readLine();  //here it read first line 
        pw.println(s);      //here it prints first line    
    }
    while((s = br.readLine())!=null); //here s read second line
                                      //note that it is not printing that line

String s = null;
    do{
        s = br.readLine();  //this time it read third line
        pw.println(s);      //now it prints third line
    }
    while((s = br.readLine())!=null);   // this time it reads fourth line

因此，此过程将继续，您的程序将逐个打印行

读取文件的内容并写入控制台

7 个答案: