随机替换字符串

Question

1:先取到文件的行数（csv格式的文件）
2:生成从1到文件行数N的随机数m
3：检查m行是否包含特征字符“String”
4：如果是则替换为“nihao”，计数器+1，否则继续从第2步开始，直到计数器到1万

求大侠帮我用java写一下程序，不胜感激~~~~~

Answer 1

[code="java"][/code]
import java.io.BufferedReader;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.PrintStream;
import java.util.Random;

public class Csvparser{

private int getToolNum(){
    int n = 0;
    try {
        //open the file
        BufferedReader reader = new BufferedReader(
                new FileReader("E:/workspace1/test/src/javaeyetest.csv"));
        String str=null;
        while(true){
            str= reader.readLine();
            n++;
            if(str ==null)break;
        }
    } catch (Exception e) {
        // TODO: handle exception
        }
    int tolnum = n-1;
    System.out.println("wen jian zui da hang shu ="+ tolnum);
    return n-1;
}

private void tiHuan( int num,int toolNum){
    try {
        //open the file
        BufferedReader reader = new BufferedReader(
                new FileReader("E:/workspace1/test/src/javaeyetest.csv"));
        FileOutputStream fos = new FileOutputStream(
                "E:/workspace1/test/src/javaeyetest1.csv");
        PrintStream stream = new PrintStream(fos);
        String str=null;

       for(int i = 0;i < toolNum;i++){
           if(i == 4){
               String strr = reader.readLine().replace("string","nihao");
               stream.println(strr);
               continue;
           }
            str= reader.readLine();
            stream.println(str);
       }           
    } catch (Exception e) {
        // TODO: handle exception
    }

}

private int suiJi(int toolNum){
    Random r=new Random(); 
    int sj = r.nextInt(toolNum);
    System.out.println("sheng cheng sui ji shu ="+sj);
    return sj;
}

public static void main(String argn[])throws IOException{   
    Csvparser ctx=new Csvparser();
    for(int i = 0;i<10;i++){
       ctx.tiHuan(ctx.suiJi(ctx.getToolNum()), ctx.getToolNum());
    }           
}

}