极客教程Java ByteBuffer getLong()方法的例子
getLong()
java.nio.ByteBuffer 类的 getLong() 方法用于读取该缓冲区当前位置的下8个字节，根据当前的字节顺序将其合成为一个长值，然后将该位置增加8。
语法
public abstract long getLong()
返回值： 该方法返回缓冲区当前位置的长值。
抛出： 该方法抛出 BufferUnderflowException - 如果该缓冲区内剩余的字节数少于4个。
下面是说明getLong()方法的例子。
例子 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);
}
}
}
输出。
Original ByteBuffer:
1233003 2292292
Byte Value: 1233003
Next Byte Value: 2292292
例子 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);
}
}
}
输出。
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
参考资料: https://docs.oracle.com/javase/9/docs/api/java/nio/ByteBuffer.html#getLong-
getLong(int index)
ByteBuffer 的 getLong(int index) 方法用于在给定的索引处读取四个字节，根据当前的字节顺序将它们合成为一个浮点数。
语法
public abstract long getLong(int index)
参数： 该方法以index（将被读取的字节的索引）为参数。
返回值： 该方法返回给定索引处的长值。
异常： 该方法抛出 IndexOutOfBoundsException。 如果索引为负数或不小于缓冲区的限制，就会抛出这个异常。
下面是一些例子来说明getLong(int index)方法。
例子 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);
}
}
}
输出。
Original ByteBuffer:
1233003 2292292
Byte Value: 1233003
Next Byte Value: 2292292
例子 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);
}
}
}
输出。
Original ByteBuffer:
1233003 2292292
Byte Value: 1233003
index is negative or smaller than the buffer's limit, minus seven
Exception Thrown : java.lang.IndexOutOfBoundsException
参考资料: https://docs.oracle.com/javase/9/docs/api/java/nio/ByteBuffer.html#getLong-int-