java

[weili86yy]

3、请编写一个字符输入流的包装类，通过这个包装类对底层字符输入流进行包装，让程序通过这个包装类读取某个文本文件（例如，一个java源文件）时，能够在读取的每行前面都加上有行号和冒号。

[shan1119]

try{
BufferedReader brF = new BufferedReader(new FileReader("fileName"));

String line = "";
int i=0;
while((line=brF.readLine()) != null){
System.out.println(++i+":"+line);
}
brF.close();
}catch(Exception e){}

[sureyor]

给个方法吧:

public String getLineData(String filePath, int lineNum) {
BufferedReader in = new BufferedReader(new FileReader(filePath));
String str = null;
int count = 0;
while ((str = in.readLine()) != null) {
count++;
if(count == lineNum){
break;
}
}
in.close();

if (str != null) {
str = new Integer(count).toString() + ":" + str;
}

return str;
}

[cursor_wang]

import java.io.*;
public class ReadFile{

public static void main(String[] args){
try{
BufferedReader br=new BufferedReader(new FileReader("D:/ReadFile.java"));
String s;
int i=0;
while((s=br.readLine())!=null)
{
System.out.println(++i+":"+s);

}
br.close();
}catch(FileNotFoundException e1){
System.err.print("File not found!");
}catch(IOException e2){
System.out.print(e2);
}
}
}