LineNumberReader類mark()方法 (LineNumberReader Class mark() method)

• mark() method is available in java.io package.

  mark()方法在java.io包中可用。

• mark() method is used to set the current position in this LineNumberReader stream and whenever we call to reset() so it will reset the stream to the position set by the most recent call of mark() method.

  mark()方法用于設(shè)置此LineNumberReader流中的當(dāng)前位置，并且每當(dāng)我們調(diào)用reset()時，它將它將流重置為由mark()方法的最新調(diào)用設(shè)置的位置。

• mark() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.

  mark()方法是一種非靜態(tài)方法，只能通過類對象訪問，如果嘗試使用類名稱訪問該方法，則會收到錯誤消息。

• mark() method may throw an exception at the time of marking the stream.

  mark()方法在標(biāo)記流時可能會引發(fā)異常。

  IOException: This exception may throw when the given parameter is not valid.

  IOException ：如果給定參數(shù)無效，則可能引發(fā)此異常。

Syntax:

句法：

public int mark();

Parameter(s):

參數(shù)：

• int r_limit – represents the limit on the number of characters that can be read before the mark gets invalid.

  int r_limit –表示標(biāo)記無效之前可以讀取的字符數(shù)限制。

Return value:

返回值：

The return type of the method is void, it returns nothing.

該方法的返回類型為void ，不返回任何內(nèi)容。

Example:

例：

// Java program to demonstrate the example // of void mark(int r_limit) method of // LineNumberReaderimport java.io.*;public class MarkOfLNR {public static void main(String[] args) throws Exception {FileReader fr_stm = null;LineNumberReader line_r = null;int val = 0;try {// Instantiates FileReader and LineNumberReaderfr_stm = new FileReader("D:\\includehelp.txt");line_r = new LineNumberReader(fr_stm);// By using read() method isto // read the character from line_rchar ch1 = (char) line_r.read();char ch2 = (char) line_r.read();char ch3 = (char) line_r.read();System.out.println("ch1: " + ch1);System.out.println("ch2: " + ch2);System.out.println("ch3: " + ch3);// By using mark() method isto// set the current position in this// line_rSystem.out.println("line_r.mark(0): ");line_r.mark(0);char ch4 = (char) line_r.read();char ch5 = (char) line_r.read();System.out.println("ch4: " + ch4);System.out.println("ch5: " + ch5);// By using reset() method isto// reset the stream to the position // set by the call mark() methodSystem.out.println("line_r.reset(): ");line_r.reset();char ch6 = (char) line_r.read();char ch7 = (char) line_r.read();char ch8 = (char) line_r.read();char ch9 = (char) line_r.read();char ch10 = (char) line_r.read();char ch11 = (char) line_r.read();System.out.println("ch4: " + ch6);System.out.println("ch5: " + ch7);System.out.println("ch6: " + ch8);System.out.println("ch7: " + ch9);System.out.println("ch8: " + ch10);System.out.println("ch9: " + ch11);} catch (Exception ex) {System.out.println(ex.toString());} finally {// with the help of this block is to// free all necessary resources linked// with the streamif (fr_stm != null) {fr_stm.close();if (line_r != null) {line_r.close();}}}} }

Output

輸出量

ch1: J ch2: A ch3: V line_r.mark(0): ch4: A ch5: W line_r.reset(): ch4: A ch5: W ch6: O ch7: R ch8: L ch9: D

翻譯自: https://www.includehelp.com/java/linenumberreader-mark-method-with-example.aspx

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