public class ReadFileDemo1 {

/**

* 获取错误文件中的记录号

* @param sourceFile

* @return

*/

public static int[] readBadFile(String sourceFile){

FileReader in = null;

LineNumberReader reader = null;

int[] array = new int[0];

try {

//获取文件总行数

long totalLine = Files.lines(Paths.get(sourceFile)).count();

//构建数组

array = new int[(int)(totalLine)];

in = new FileReader(sourceFile);

reader = new LineNumberReader(in);

String s = reader.readLine();

int i = 0;

while(s != null){

System.out.println(s);

int index = s.indexOf(":");

array[i++] = Integer.parseInt(s.substring(2,index)) + 1;

s = reader.readLine();

}

} catch (IOException e) {

e.printStackTrace();

} finally {

closeResource(in, reader);

}

return array;

}

/**

* 读取文件指定行数(读取一行)

* @param filePath

* @param lineNumber

*/

public static String readAppointedLineNumber(String filePath,int lineNumber){

String appointedLine = "";

FileReader in = null;

LineNumberReader reader = null;

try {

in = new FileReader(filePath);

reader = new LineNumberReader(in);

long totalLine = Files.lines(Paths.get(filePath)).count();

if(lineNumber < 0 || lineNumber > totalLine){

return "指定行【"+lineNumber+"】不在文件行数范围内";

}

int line = 1;

reader.setLineNumber(lineNumber);

long i = reader.getLineNumber();

String s = "";

while((s = reader.readLine()) != null){

if(i == line){

appointedLine = s;

break;

}

line++;

}

return appointedLine;

} catch (FileNotFoundException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

} catch (Exception e) {

e.printStackTrace();

} finally {

closeResource(in, reader);

}

return appointedLine;

}

/**

* 读取文件指定行数(读取多行)

* @param filePath

* @param lineArray

*/

public static List readAppointedLineNumberArray(String filePath,int[] lineArray){

FileReader in = null;

LineNumberReader reader = null;

List resultStr = new ArrayList();

//对数组按从小到大排序

lineArray = sortArray(lineArray);

if(lineArray.length == 0){

return new ArrayList();

}

try {

in = new FileReader(filePath);

reader = new LineNumberReader(in);

int lineNumber = lineArray.length;

int line = 1;

int i = 0;

String s = "";

while((s = reader.readLine()) != null){

if(i < lineNumber && line ==lineArray[i]){

i++;

System.out.println(s);

resultStr.add(s);

}

line++;

}

} catch (FileNotFoundException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

} catch (Exception e) {

e.printStackTrace();

} finally {

closeResource(in, reader);

}

return resultStr;

}

/**

* 关闭资源

* @param in

* @param reader

*/

public static void closeResource(FileReader in,LineNumberReader reader){

try {

if(reader != null){

reader.close();

}

if(in != null){

in.close();

}

} catch (IOException e) {

e.printStackTrace();

}

}

/**

* 冒泡排序

* @param array

* @return

*/

public static int[] sortArray(int[] array){

if(array.length == 0){

return array;

}

for(int i = 0; i < array.length; i++){

for(int j = 0; j < array.length-i-1; j++){

if(array[j+1] < array[j]){

int temp = array[j+1];

array[j + 1] = array[j];

array[j] = temp;

}

}

}

return array;

}

}

原文：https://www.cnblogs.com/baoqinghe/p/13277088.html