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Java ByteBuffer getLong()用法及代碼示例


getLong()

java.nio.ByteBuffer類的getLong()方法用於讀取此緩衝區當前位置的下八個字節，根據當前字節順序將它們組成一個long值，然後將該位置加8。

用法:

public abstract long getLong()

返回值：此方法返回緩衝區當前位置的long值。


拋出：此方法拋出BufferUnderflowException-如果此緩衝區中剩餘的字節數少於四個。

下麵是說明getLong()方法的示例：

範例1：

// Java program to demonstrate 
// getLong() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
  
    public static void main(String[] args) 
    { 
  
        // Declaring the capacity of the ByteBuffer 
        int capacity = 16; 
  
        // Creating the ByteBuffer 
        try { 
  
            // creating object of ByteBuffer 
            // and allocating size capacity 
            ByteBuffer bb = ByteBuffer.allocate(capacity); 
  
            // putting the long value in the bytebuffer 
            bb.asLongBuffer() 
                .put(1233003) 
                .put(2292292); 
  
            // rewind the Bytebuffer 
            bb.rewind(); 
  
            // print the ByteBuffer 
            System.out.println("Original ByteBuffer: "); 
            for (int i = 1; i <= capacity / 8; i++) 
                System.out.print(bb.getLong() + " "); 
  
            // rewind the Bytebuffer 
            bb.rewind(); 
  
            // Reads the long at this buffer's current position 
            // using getLong() method 
            long value = bb.getLong(); 
  
            // print the long value 
            System.out.println("\n\nByte Value: " + value); 
  
            // Reads the  long at this buffer's next position 
            // using getLong() method 
            long value1 = bb.getLong(); 
  
            // print the long value 
            System.out.print("\nNext Byte Value: " + value1); 
        } 
  
        catch (BufferUnderflowException e) { 
  
            System.out.println("\nException Thrown : " + e); 
        } 
    } 
}
輸出： 
Original ByteBuffer: 
1233003 2292292 

Byte Value: 1233003

Next Byte Value: 2292292

範例2：

// Java program to demonstrate 
// getLong() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
  
    public static void main(String[] args) 
    { 
  
        // Declaring the capacity of the ByteBuffer 
        int capacity = 16; 
  
        // Creating the ByteBuffer 
        try { 
  
            // creating object of ByteBuffer 
            // and allocating size capacity 
            ByteBuffer bb = ByteBuffer.allocate(capacity); 
  
            // putting the long value in the bytebuffer 
            bb.asLongBuffer() 
                .put(1233003) 
                .put(2292292); 
  
            // rewind the Bytebuffer 
            bb.rewind(); 
  
            // print the ByteBuffer 
            System.out.println("Original ByteBuffer: "); 
            for (int i = 1; i <= capacity / 8; i++) 
                System.out.print(bb.getLong() + " "); 
  
            // rewind the Bytebuffer 
            bb.rewind(); 
  
            // Reads the long at this buffer's current position 
            // using getLong() method 
            long value = bb.getLong(); 
  
            // print the long value 
            System.out.println("\n\nByte Value: " + value); 
  
            // Reads the  long at this buffer's next position 
            // using getLong() method 
            long value1 = bb.getLong(); 
  
            // print the long value 
            System.out.print("\nNext Byte Value: " + value1); 
  
            // Reads the  long at this buffer's next position 
            // using getLong() method 
            long value2 = bb.getLong(); 
        } 
  
        catch (BufferUnderflowException e) { 
            System.out.println("\nthere are fewer than "
                               + "eight bytes remaining in this buffer"); 
            System.out.println("Exception Thrown : " + e); 
        } 
    } 
}
輸出： 
Original ByteBuffer: 
1233003 2292292 

Byte Value: 1233003

Next Byte Value: 2292292
there are fewer than eight bytes remaining in this buffer
Exception Thrown : java.nio.BufferUnderflowException

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

getLong(int索引)

ByteBuffer的getLong(int index)方法用於讀取給定索引處的四個字節，並根據當前字節順序將它們組成一個float值。

用法:

public abstract long getLong(int index)

參數：此方法將索引(將從中讀取Byte的索引)作為參數。


返回值：此方法返回給定索引處的long值。

異常：此方法引發IndexOutOfBoundsException。如果index為負或不小於緩衝區的限製，則拋出此異常。

以下示例說明了getLong(int index)方法：

範例1：

// Java program to demonstrate 
// getLong() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
  
    public static void main(String[] args) 
    { 
  
        // Declaring the capacity of the ByteBuffer 
        int capacity = 16; 
  
        // Creating the ByteBuffer 
        try { 
  
            // creating object of ByteBuffer 
            // and allocating size capacity 
            ByteBuffer bb = ByteBuffer.allocate(capacity); 
  
            // putting the long value in the bytebuffer 
            bb.asLongBuffer() 
                .put(1233003) 
                .put(2292292); 
  
            // rewind the Bytebuffer 
            bb.rewind(); 
  
            // print the ByteBuffer 
            System.out.println("Original ByteBuffer: "); 
            for (int i = 1; i <= capacity / 8; i++) 
                System.out.print(bb.getLong() + " "); 
  
            // rewind the Bytebuffer 
            bb.rewind(); 
  
            // Reads the long at this buffer's current position 
            // using getLong() method 
            long value = bb.getLong(0); 
  
            // print the long value 
            System.out.println("\n\nByte Value: " + value); 
  
            // Reads the  long at this buffer's next position 
            // using getLong() method 
            long value1 = bb.getLong(8); 
  
            // print the long value 
            System.out.print("\nNext Byte Value: " + value1); 
        } 
  
        catch (IndexOutOfBoundsException e) { 
  
            System.out.println("\nindex is negative or "
                               + "smaller than the buffer's limit, "
                               + "minus seven"); 
            System.out.println("Exception Thrown : " + e); 
        } 
    } 
}
輸出： 
Original ByteBuffer: 
1233003 2292292 

Byte Value: 1233003

Next Byte Value: 2292292

範例2：

// Java program to demonstrate 
// getLong() method 
  
import java.nio.*; 
import java.util.*; 
  
public class GFG { 
  
    public static void main(String[] args) 
    { 
  
        // Declaring the capacity of the ByteBuffer 
        int capacity = 16; 
  
        // Creating the ByteBuffer 
        try { 
  
            // creating object of ByteBuffer 
            // and allocating size capacity 
            ByteBuffer bb = ByteBuffer.allocate(capacity); 
  
            // putting the long value in the bytebuffer 
            bb.asLongBuffer() 
                .put(1233003) 
                .put(2292292); 
  
            // rewind the Bytebuffer 
            bb.rewind(); 
  
            // print the ByteBuffer 
            System.out.println("Original ByteBuffer: "); 
            for (int i = 1; i <= capacity / 8; i++) 
                System.out.print(bb.getLong() + " "); 
  
            // rewind the Bytebuffer 
            bb.rewind(); 
  
            // Reads the long at this buffer's current position 
            // using getLong() method 
            long value = bb.getLong(0); 
  
            // print the long value 
            System.out.println("\n\nByte Value: " + value); 
  
            // Reads the  long at this buffer's next position 
            // using getLong() method 
            long value1 = bb.getLong(11); 
  
            // print the long value 
            System.out.print("\nNext Byte Value: " + value1); 
        } 
  
        catch (IndexOutOfBoundsException e) { 
  
            System.out.println("\nindex is negative or"
                               + " smaller than the buffer's limit, "
                               + "minus seven"); 
            System.out.println("Exception Thrown : " + e); 
        } 
    } 
}
輸出： 
Original ByteBuffer: 
1233003 2292292 

Byte Value: 1233003

index is negative or smaller than the buffer's limit, minus seven
Exception Thrown : java.lang.IndexOutOfBoundsException

參考： https://docs.oracle.com/javase/9/docs/api/java/nio/ByteBuffer.html#getLong-int-



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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 ByteBuffer getLong() 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。