Java LongBuffer mark()用法及代碼示例

java.nio.LongBuffer類的mark()方法用於將LongBuffer的當前位置標記為該緩衝區的標記。

用法:

public LongBuffer mark()

參數：此方法不接受任何參數。

返回值：在將緩衝區的標記設置在當前位置之後，此方法返回此LongBuffer。

下麵是說明mark()方法的示例：

範例1：

// Java program to demonstrate 
// mark() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
  
    public static void main(String[] args) 
    { 
  
        try { 
  
            long[] darr = { 10, 20, 30, 40 }; 
  
            // creating object of LongBuffer 
            // and allocating size capacity 
            LongBuffer lb = LongBuffer.wrap(darr); 
  
            // try to set the position at index 2 
            lb.position(2); 
  
            // Set this buffer mark position 
            // using mark() method 
            lb.mark(); 
  
            // try to set the position at index 4 
            lb.position(4); 
  
            // display position 
            System.out.println("position before reset: "
                               + lb.position()); 
  
            // try to call reset() to restore 
            // to the position we marked 
            lb.reset(); 
  
            // display position 
            System.out.println("position after reset: "
                               + lb.position()); 
        } 
  
        catch (InvalidMarkException e) { 
            System.out.println("New position "
                               + "is less than "
                               + "the position "
                               + "marked before "); 
            System.out.println("Exception throws: "
                               + e); 
        } 
    } 
}

輸出：

position before reset: 4
position after reset: 2

範例2：演示InvalidMarkException

// Java program to demonstrate 
// mark() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
  
    public static void main(String[] args) 
    { 
  
        try { 
  
            long[] darr = { 10, 20, 30, 40 }; 
  
            // creating object of LongBuffer 
            // and allocating size capacity 
            LongBuffer db = LongBuffer.wrap(darr); 
  
            // try to set the position at index 2 
            db.position(2); 
  
            // Set this buffer mark position 
            // using mark() method 
            db.mark(); 
  
            // try to set the position at index 1 
            db.position(1); 
  
            // display position 
            System.out.println("position before reset: "
                               + db.position()); 
  
            // try to call reset() to restore 
            // to the position we marked 
            db.reset(); 
  
            // display position 
            System.out.println("position after reset: "
                               + db.position()); 
        } 
  
        catch (InvalidMarkException e) { 
            System.out.println("\nNew position "
                               + "is less than "
                               + "the position "
                               + "marked before "); 
            System.out.println("Exception throws: "
                               + e); 
        } 
    } 
}

輸出：

position before reset: 1

New position is less than the position marked before 
Exception throws: java.nio.InvalidMarkException

參考： https://docs.oracle.com/javase/9/docs/api/java/nio/LongBuffer.html#mark–

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注：本文由純淨天空篩選整理自RohitPrasad3大神的英文原創作品 LongBuffer mark() method in Java with Examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。