Java°´Ö¸¶¨ÐÐÊý¶ÁÈ¡Îļþ

package test
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.LineNumberReader;
public class ReadSelectedLine{
// ¶ÁÈ¡ÎļþÖ¸¶¨ÐС£
static void readAppointedLineNumber(File sourceFile, int lineNumber)
throws IOException {
FileReader in = new FileReader(sourceFile);
LineNumberReader reader = new LineNumberReader(in);
String s = "";
if (lineNumber <= 0 || lineNumber > getTotalLines(sourceFile)) {
System.out.println("²»ÔÚÎļþµÄÐÐÊý·¶Î§(1ÖÁ×ÜÐÐÊý)Ö®ÄÚ¡£");
System.exit(0);
}
int lines = 0;
while (s != null) {
lines++;
s = reader.readLine();
if((lines - lineNumber) == 0) {
System.out.println(s);
System.exit(0);
}
}
reader.close();
in.close();
}
// ÎļþÄÚÈݵÄ×ÜÐÐÊý¡£
static int getTotalLines(File file) throws IOException {
FileReader in = new FileReader(file);
LineNumberReader reader = new LineNumberReader(in);
String s = reader.readLine();
int lines = 0;
while (s != null) {
lines++;
s = reader.readLine();
}
reader.close();
in.close();
return lines;
}

/**
* ¶ÁÈ¡ÎļþÖ¸¶¨ÐС£
*/
public static void main(String[] args) throws IOException {
// Ö¸¶¨¶ÁÈ¡µÄÐкÅ
int lineNumber = 2;
// ¶ÁÈ¡Îļþ
File sourceFile = new File("D:/java/test.txt");
// ¶ÁÈ¡Ö¸¶¨µÄÐÐ
readAppointedLineNumber(sourceFile, lineNumber);
// »ñÈ¡ÎļþµÄÄÚÈݵÄ×ÜÐÐÊý
System.out.println(getTotalLines(sourceFile));
}
}