java 读取文件指定行的内容

/**??*?读取文件指定行。??*/public?class?ReadSelectedLine?{//?读取文件指定行。?static?void?readAppointedLineNumber(File?sourceFile,?int?lineNumber)?throws?IOException?{FileReader?in?=?new?FileReader(sourceFile);LineNumberReader?reader?=?new?LineNumberReader(in);String?s?=?reader.readLine();if?(lineNumber?<?0?||?lineNumber?>?getTotalLines(sourceFile))?{System.out.println("不在文件的行数范围之内。");}{while?(s?!=?null)?{System.out.println("当前行号为:"?+?reader.getLineNumber());System.out.println(s);System.exit(0);s?=?reader.readLine();}}reader.close();in.close();}//?文件内容的总行数。?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;}public?static?void?main(String[]?args)?throws?IOException?{????????//?读取文件?File?sourceFile?=?new?File("d:/11.txt");????????//?获取文件的内容的总行数?int?totalNo?=?getTotalLines(sourceFile);System.out.println("There?are?"+totalNo+?"?lines?in?the?text!");//?指定读取的行号?int?lineNumber?=?2;//?读取指定的行?readAppointedLineNumber(sourceFile,?lineNumber);}}