关于连接字符串

Question

假如有个txt文档，里面的内容为：
abc
huhu
nunu
koko
bfbf
dbdb
yuyu
现在想要在他们每个前面都加上一个 * 号，请问用程序怎么编写呢？

Answer 1

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.Reader;
import java.io.Writer;public class Test33 { public static void main(String[] args) throws Exception {
Reader reader = new FileReader(new File("out.txt"));
BufferedReader br  = new BufferedReader(reader);
String line = "";
StringBuilder sb = new StringBuilder();
while(null != (line = br.readLine())){
sb.append("*").append(line).append("\n");
}
System.out.println(sb.toString());

Writer writer = new FileWriter(new File("out.txt"));
writer.write(sb.toString());
writer.close();
}
}

Answer 2

public static void main(String[] args) throws Exception {
String fileName="f:/test4/a1.txt";
StringBuilder sb = new StringBuilder();
BufferedReader br = new BufferedReader(new InputStreamReader(
new FileInputStream(fileName)));

String line;
int i=1;
while ((line = br.readLine()) != null) {
String tmp="*"+line+"\r\n";
System.out.println("["+(i++)+"]"+tmp);
sb.append(tmp);
}
System.out.println("sb:\n"+sb.toString());
br.close();
if(sb.toString()!=null && !"".equals(sb.toString())){
BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(
new FileOutputStream(fileName)));
bw.write(sb.toString());
bw.flush();
bw.close();
}
}